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JULY  1994 

ISSUE  #  406 

USA  $2.95 

CANADA  $3.95 

A  WGI  Publication 

Jnteniatianal  Edition 


All  About 

POSltlOIH 


Wori^ 


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I  Feel  The  Comfort  Of  Extended 
.Operations  With  The  1C-T2  lA!  J 


|(T4!A 

UHFFM 
TraiTsceivtf 


Moximum  Comfml 

flfistoniff  Coftstructtoi  -  This  special 

malerial  pro\ides  a  comfortible,  pOMtive 
grip.  The  compaa  design  fits  ihe  natural 
oiHT  of  your  fingers  and  hand  -  especial^ 
welcome  during  long  operating  times, 

BockBt  Key  pad  -  Ample  spacing  behveen 
kej's  for  posiii\e,  error  free  operaiion. 

lurge  Displdy  -  Indicates  17  different 

functions,  bauery  capacity  and 
sub  band  frequency. 


Full  Crossbonci  Duplex  Operotioii 

Dtrd  Band  Receivt  Capcibiiity  -  Pennits 
reception  of  another  band  (le.:  440  MHz  cm 
tbeIC-T21A). 

Full  Crossbctitd  Duplex  Op€ratbR  -  ^sible 
with  the  unique  'Whisper  mode"  microphone 
(standard)  for  telephone  type  QSO's. 


6  Hours  Operating  Time"^ 

Low  Power  Consuniption  -  Coni^unies  oidir 
8  mA  while  standing  by. 

A»to  Power  Control  -  Consc^r\es  the  battery 
by  monitoring  the  repeater  signal  strength 
and  selecting  the  best  matching  output  power 
from  5  levels  (down  to  15  mW). 
Auto  low  Power  Function  -  Automatically 
selects  15  mW  just  before  banery^  cxliausiion 
so  you  can  complete  your  QSO. 

*  55 10  6  hdur^  witlj  1 : 1:8  duty  cyck  (Tk  high  :  RA  :  .Siimdby) 

Battery  Capacity  Indicator  - 

Shows  bauerj-  capacit)i 

New  Scanning 
Standards 

Ultra  High  Speed  Scan  - 

3  to  4  times  faster  than 
most  other  handlields 
(33  channels/sec,  12,5 
memoiychysecO- 
Bonus  Bond  -  Can  be 
scanned  while  the 
main  band  Is  beui|; 
scanned  (e.g,:  70  cm 
forlhelCTaiA), 


For  more  information  call  our 
broclriire  hotlirte:  (206)  450-6088 


5^>^/5?^ 


i^Q^/y 


6  Priority  Watch  Wodes  -  Check  for  other 
signals  while  operating  on  a  VTQ  frequency* 

Ultrs-Convenient 
Repeater  Operations 

Suboudible  Tofie  Scon  -  Detects,  displaji^ 

and  programs  the  tone  frequency  into  the 
\T0.  PermiLs  access  to  a  repeater  when  you 
don't  know  the  tone  frequency 

Auto  Repeater  Function  -  Automatically 
activates  repeater  settings  (duplex  OX/OFF, 
duplex  direction,  tone  encoder  ON/OFF) 
when  the  operating  frequeoCT  falls  in  the 
repeater  output  range. 

Repeater  Memory  -  QuicHj'  recall  setting 
of  your  last  worked  repeater  (RPT-M  key). 

5  DTWF  Memories  -  Automatica%  dial  your 
finrorite  telephone  numbers. 
Selectoble  DTMF  Transmission  Speed  - 
Adjust  the  IC-T21A/I41A  to  the  capabilities  of 
the  repeater  (5  cps,  2,5  cps,  1 .6  cps,  1  cps). 


Powerful  6  W  Output  Power* 

Our  newly  designed  SC-1257  power  module 
provides  all  the  power  necessary  to  reach 
fringe  areas.  Accepts  4-16  V  input, 

■•  Wllh  Jk  lis  V  DC  power  Murce, 

Innovative  Memory  Functions 

114  Memory  Channels  -  Store  all  repeater 

information. 

Memory  Select  Channels  -  For  quick 

access,  up  to  30  can  be  designated  Memory 

Select  Channels. 

Memory  Transfer  -  Quickly  transfers  a 
memor>  ckmneFs  contents  to  VFO.  Useftil  for 

searching  for  signals  near  a  meniorv  cbanncL 

EEPROM  -  Memory  information  is  retained 
virtually  forever 

And  More! 

•  IndDdes  FtexltstF  Antenni,  Bdt  Clip^  Hzndstrifi, 
lecliaii?3Jtile  M-€tI  HaJirn  Padt  ^iJ  Charger 
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Tone  SquelcJi 

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!■  IMF  Thi  Iffi  h»  ii  I  r^Tii^  ti^w^  rf  rfflll  hr 


ClHCLjt  \  73  aS4  HtAO^H  S£.HV1C^  i^AHQ 


I 


INTERNATIONAL  INC 


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id  Below  $200!! 

ATH  ™  SERIES  FEATURES: 

•  Easy  to  use  -  simple  controls 

•  Ultra  fast  response  time 

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Factory  Direct 
Order  Lines 

SAME  DAY  SHIPMEI 


Orders  &  Information 


Orders  On  I 
AX  305-561-913'! 


Model  1350 

Economy  Frequency  Counter 
1-1300  MHZ,  3  gate  times, 
Hold  switch 
{No  ATH  or  Bar  Graph)  ....$119, 


mstrunrients  are 
true  Pocket  Size: 


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ACCESSORIES 

#CC-90  Soft  Case  for  all  models........... $12. 

#TA-90  Telescope  BNC  antenna............. 12. 

#TA-90-L  Telescope  Elbow  BNC  antenna .,„.16. 

ttRD-ISO  150  MHZ  Rubber  Duck  antenna ..„16. 

#RD-2750  27  &  50  MHZ  Rubber  Duck  antenna.... 28. 

#RD^50  450  MHZ  Rubber  Duck  antenna  ..........16. 

#RD-800  Cellular  phone  band  RD  antenna 29. 

#e/6A  ABOVE  7  il^ms,  SAVE  $00  99. 

#M-207-IC  Interface  Cable  MFJ  ant.  analyzers,... ..10. 

#P-110  200  MHZ  1X-10X  probe..... 39. 

#LP-22  Low  Pass,  Audio  probe „„„.„_„„.,„25. 

#DC-10  Direct,  50  OHM  probe 20. 


FEATURES 


ATM -10 

$149 


ATH '15 

$189 


ATH-30      ATH-50 


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Antennas  are 

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reg  $f79 

reg  $235 

reg  $293 

reg  $333 

FREQUENCY  RANGE 

1  MHZ  - 
1200  MHZ 

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OPTIONAL 

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Hf-Z  LOW  RANGE 

NO 

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OPTION  #HST-15  is  3 

can  t>e  ordered  with  any 

I  high  accuracy,  high  stability,  time  base 
ATH  series  modet  (0,2PPM  TCXO) 

upgrade  that 
.$100- 

Extend  readability  distance  with  BAND  PASS  FILTERS,  $49  ea. 

#LP-60       DC-eOiyHZ  #BP-150      130 -500  MHZ 

#HP-400    400  -  1500  MHZ  #HP-800     800  -  20O0  MHZ 

#BP**4     All  4  Filters     $189 


Terms:  Shipping/handling  charges  U.S.  &  Canada  S%  ($5  mln„  $10  max)  Others  add  15%,  FL  residents  add  6%  tax,  COD  fee  $5. 
VISA,  MC,  Discover  accepted.  Prices  &  specifications  subject  to  change  without  notice  or  obligation. 


\'*j^^.' 


-  l3lff&tc'Z'*y-f3N''freAOcR  StRAflUc'v AnD 


JRC 


160-10  Meters  PLUS  6  Meter  Transceiver 


pcwsfi 


4N     iJ    iJA 

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M-Vft) 


hiEMO 


^«*"    h-J-usie" 


atT/«Hs 


AF-$^HF 


VJ     / 


■•^w«tin 


MfMOFlv 


ORlH 


®-flWWC; 


Fifteen 


reasons  why  your  next  HF 
ver  should  be  a  JST-245.  .  . 


1 


2 


3 


4 


5 


6 


All-Mode  Operation  (SSB,CW,AM,AFSK,FM)  on  ell  HF  amateur 
bands  and  6  meters.  JST-145,  same  as  JST-245  but  without  6 
meters  and  built-in  antenna  tuner. 

•  JST-145  COMING  SOON  • 

MOSFET  POWER  AMPLIFIER  -  Final  PA  utilizes  RF  MOSFETs 
to  achieve  low  distortion  and  high  durability.  Rated  output  Is  10 
to  150  watts  on  all  bands  inciudtng  6  meters. 

AUTOMATIC  ANTENNA  TUNER  •  Auto  tuner  included  as 
standard  equipment.  Tuner  settings  are  automaticaily  stored 
in  memory  for  fast  QSY. 

MULTIPLE  ANTENNA  SELECTION  •  Three  antenna  connec- 
tions are  user  selectable  from  front  panel.  Antenna  selection  can 
be  stored  in  memory. 

GENERAL  COVERAGE  RECEIVER*  100  kHz-30MHz,  plus  48- 
54  MHz  receiver.  Electronically  tuned  front-end  filtering,  quad- 
FET  mixer  and  quadruple  conversion  system  {triple  conversion 
for  FM)  results  in  excellent  dynamic  range  {>1  OOdB)  and  3rd  order 
fCPof+20dBm. 

IF  BANDWIDTH  FLEXIBILITY  *  Standard  2.4  kHz  filter  can  be 
narrowed  continuously  to  800  Hz  with  variable  Bandwidth  Control 
(BWC).  Narrow  SSB  and  CW  filters  for  2nd  and  3rd  IF  optional, 

QRM  SUPPRESSION  •  Other  interference  rejection  features 
include  Passband  Shift  (PBS),  dual  noise  blanker,  3-step  RF  atten- 
uation, IF  notch  filter,  selectable  AGO  and  all-mode  squelch. 


8 

10 
11 


12 
13 

14 


15 


NOTCH  TRACKING  •  Once  tuned,  the  IF  notch  filter  will  track  the 
offending  heterodyne  (±10  Khz)  [f  the  VFO Irequency  is  changed, 

DDS  PHASE  LOCK  LOOP  SYSTEM  •  A  single-Cfystal  Direct 
Digital  Synthesis  system  is  utilized  for  very  low  phase  noise. 

CW  FEATURES  •  Full  break-in  operation,  variable  CW  pitch,  built 
in  electronic  keyer  up  to  60  wpm. 

DUAL  VFOs  •  Two  separate  VFOs  for  split-frequency  operation. 
Memory  registers  store  most  recent  VFO  frequency,  mode,  band- 
width and  other  important  parameters  for  each  band. 

200  MEMORIES  •  Memory  capacity  of  200  channels,  each  of 
which  store  frequency,  mode,  AGC  and  bandwidth. 

COMPUTER  INTERFACE  •  Built-in  RS-232C  interface  for 
advanced  computer  applications. 

ERGONOMIC  LAYOUT  •  Front  panel  features  easy  to  read  color 
LCD  display  and  thoughtful  placement  of  controls  for  ease  of  oper- 
ation. 

HEAVY-DUTY  POWER  SUPPLY  •  Built-in  switching  power 
supply  with  Power  Factor  Correction  (PFC)  and  "silenf  cooling 
system  designed  for  continuous  transmission  at  maximum 
output 

This  device  has  not  been  approved  by  the  Federal  Commurkications  Commission.  This, 
device  is  not,  and  may  not  be,  offered  for  sale  or  lease,  or  sold  or  leased  untilthe  appf^oval 
of  the  FCC  has  been  obtatned." 


JRC]  0apatRadiaCo.,Iid. 


430  Park  Ave.,  2nd  Floor  New  York,  NY  10022        Phone:  (212)  355-1 180  Fax:  (212)  319-6227 

CIRCLE  1S9  ON  READER  SERVICE  CARD 


THE  TEAM 

PUBLlSHEFt'EDITOR 
Wayne  Greeo  W2NSD/1 

ASSOCIATE  PUBLISHER  EDFTOe 
David  Cass idyNIGPH 

I^ANAGING  EDITOR 
Hope  Currier 

SENIORnreCHMICAL  EDITOR 
Chaiies  Warrington  WAl  RZW 

EDTTORrAL  ASSOCIATE 
Joyce  SaMeiie 

CONTRIBUTING  EDITORS 
B\\\  Brown  WBaELK 
Mike  Bryce  WB8VGE 
Joseph  E.  Cair  K4IPV 
David  CowhtgWAILBP 
Michael  GeierKBlUM 
Jim  Gray  W1 XU/7 
Chuck  Hougtilon  WB6IGP 
Arnie  Johnson  N1  BAG 
Dl  Marc  Leavey  WA3AJR 
Andy  MacAllister  WA5ZIS 
Joe  Moell  K0OV 
Carofe  Penv  WB2MGP 
JeWrey  Sloman  Nl  EWO 

ADVERTISTHG  SALES  MANAGER 

Dan  Harper 

ADVERTJSING  COORDINATOR 

Judy  Walker 

1-603'924-0058 

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FAX:  1-603-924-9327 

GRAPHIC  DESIGN 

Suzanne  Self 

GRAPHIC  SERVICES 
Film  Works,  inc. 
Hancock  NH 

QRAPHtCS  MANAGER 

Linda  Drew 

CIRCULATION  MANAGER 
Harvey  Chandler 

To  subscribe:  1-800-289-0388 

WAYNE  GREEN,  INC. 

Editorial  Officas 
70  Route  202N 
Peterborough  NH  03458 
1  -603-924-0056: 
FAX:  1-603-924-9327 


Subscription  Servi 
1  -BOO-289  0388 

Foreign  Subscribers 
1^609-461-8432 


Reprints:  $3.00  per  artfde. 
Back  issues:  S4  00  each. 
Whle  to  73  Amateur  Radio  Today. 
Reprints,  70  Route  202N, 

Printed  in  the  U,S.A.  by  Quad 
Graphics,  Thomaston.  Georgia, 


10 
16 
24 
38 
42 
44 


30 
34 


J^Amateur 

Radio  Today 


Jul)'  1994 

Issue  #406 


TABLE  OF  CONTENTS 


vw»r-i-*«p<*«9  V  v  ■ 


FEATURES 


The  Global  Positioning  System 

An  overview..,,., ..„..„ 

World's  Smallest  10  GHz  ATV  Transmilter 

Build  one  on  a  PCB  using  only  a  few  components.-.^ HB9SLV, 

EMI/RFI  Defense  Strategies  for  Hams 

Keep  those  troublemaking  signals  out  of  your  mobtie  ifistallatioa 

A  Delayed  Video  Trigger  for  Your  Oscilloscope 

Convert  your  surplus  scope ,„„ ,„*.*.„„ ,. 

Multiband  Half-Wave  Delta  Loop  (MHDL) 

A  simple  20-10  meter  antenna  wftti  an  80-30  meter  bonus 

Ttie  Improved  Resonant  FeedHne  Dipole 

A  compact,  low  impedance,  end-fed  HF  antenna  that  needs  no  tuner 


REVIEWS 


-  •Dv  viia*«  h* 


i  d  *  I  ««  A  t-^-k 


,WA4BLC 
HB9RKR 
...N7MGT 
,..XC3XM 
WA6QeU 
..W207H 


S  &  S  Engineering  s  Frequency  Counter  Kit 

Now  you  can  count  frequencies  til  your  hearfs  content WBeVGE 

The  LDG  Electronics  FC-1 

A  small,  flexible  tox  controller  and  CW  IDer. ..K4CHE 


DEPARTMENTS 


$4  Above  and  Beyond 

73  Ad  Index 

66  Ask  Kaboom 
63  ATV 

61  Barter  "n'  Buy 

62  Carr's  Comer 

67  Dealer  Directory 
17  Feedback  Index 
62  Ham  Help 

54  Hams  wttli  Class 

50  Hamsals 

60  Homing  In 

6  Letters 

4  Never  Say  Die 

82  New  Prdctucts 

S6  Packei  &  Comput 

68  Pro|>agation 
65  QRP 

6  QRX 

6$  Random  Output 

49  RTTY  Loop 

70  73  International 

76  Special  Events 


Load  your  marine  GPS  receiver  with  highway  maps  and  know  where  you're  goings 
Turn  to  page  ro,  (Photo  by  Gordon  West  WB6N0A} 


FEEDBACK.^ 
^DBACKt 

Ws  like  being  there — right 
here  in  our  offices!  How'' 
Just  take  advantage  of 
our  FEEDBACK  card  on 
page  17.  You'll  notkse  a 
feedback  number  al  the 
begi-nmng  ot  eadi  artK^e 
and  cofumn.  We'd  Jike  you 
10  rate  what  you  read  so 
tf>ai  we  can  print  what 
tyo&soi  tilings  you  like 
best-  And  then  we  will 
dmw  one  Feedback  card 
each  month  for  a  free 
subscription  to  73. 


On  the  cover  Hit  the  trait  wfth  the  tcom  GP-22  GPS  receiver  See  thts  month's  cover  story,  'Tha  Gfoda/  Posrfioning 
System, "  starting  on  page  10.  (Photo  tjy  David  Cassidy  NlGPH.) 

Manuscripts  CQntribuitpns  In  the  torm  oi  m an u scripts  wilti  drawings  and' or  photographs  ere  welcome  and  wHE 
tje  considered  for  possible  pubfication.  We  can  assume  no  responsibility  for  loss  or  damage  to  any  maleflal, 
Please  enclose  a  starnped,  selt-address^d  envelope  with  each  submission.  Payment  for  the  use  of  any  unsolicit- 
ed material  will  be  Tnade  upon  publication  A  premium  will  be  paid  for  accepted  articles  thai  have  been  sybmllted 
etectronicaHy  j CompuServe  ppn  703tOJ75)  or  on  dish  3^  an  EBM compatible  ASCII  tile  You  can  aJso  cefiiact  us 
at  the  73  BBS  at  (603)  924  9343,  300—2400  baud.  9  daia  bfjs^  no  panty,  one  Slop  bit  All  contnbutions  shouJd  be 
directed  to  (tie  73  editor^  offices.  'Uovt  to  WH&  tqr  7J  "  gyldelfnes  are  availabie  upon  ret|uest  US  citizens  must 
indude  theif  Social  Sacyftty  rnmibef  witti  siibfiBtted  maoyat^^^s. 

73  Amatmir  Ramo  Today  fISSN  10S3-M22)  is  (jtifaiT^ed  monthfy  tiy  Vlfayne  Green  Inc..  70  Rpyte  202  Nofthp 
Peiert>OfOugh  NH  0345^  Entire  conienis  i;i994  by  Wayrke  Green  tnc  No  part  of  this  pubrhcation  may  tse  repro- 
duced without  wrttlen  permisEan  ot  the  publisher.  For  Subscription  Services,  wiire  to  73  AmaTeur  f^adh  Todny, 
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second  c^ass  maiJ  registration  #178101.  Canadian  GST  regisgatton  #125393314  Microfilm  Edition — Univemity 
Microfilm.  Ann  Arbor  MC  4aiOG  POSTMASTER:  Send  address  changes  to  T3  Amareur  Radio  Today,  RO,  Box 
7633,  R»vefUjn  NJ  08077  769»3. 

Contrad:  Under  tiie  power  v^^ested  m  me  by  the  almigfity  Oz,  I  oomrr^and  you  to  get  a  Ide!  Listening  to  your 
erwjfess^  mindless  ng  babb^  is  bonng  Don  t  be  a  broken  record.  Get  oK  your  center  at  gravity  and  try  someitiing 
new. 


Editorial  Offices 

70  Route  202H 

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pnone:  603-924  OOSa 

Advertising  Offices 

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Circulation  Offices 

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J 


73  Amateur  Radio  Today  •  July  J  994  3 


PIlHFiber  1  ofi  your  Feedback  card 


Ni 


EVER  SAY  DIE 


Wayne  Green  W2NSD/1 


Here  They  Go! 

Yes.  I  know  you're  busy  figMing  the 
pEleups  on  20m  and  could  care  less 
about  our  2400  MHz  band.  You're  fo* 
cused  on  the  here  and  now  and  dcn'l 
want  10  be  bothered  about  five  or  10 
years  from  now.  Let  the  future  take 
care  of  ilaelf, 

The  only  reason  w©  hav©  our  coun- 
try Is  that  a  bunch  at  fanatics  fought  for 
il  a  couple  hundred  years  ago.  They 
believed  in  what  Ibey  were  doing.  I'm 
sure  glad  there's  no  way  fof  them  to 
see  what  a  mess  youVe  imtfe  of  ttieir 
vision  ana  hopes.  Yep,  you.  You're  the 
man.  You  re  the  one  who  has  been  re- 
electing your  crooks  to  Washington, 
and  It's  Congress  that's  made  the  big 
mess  we're  trying  to  cope  with. 

Well.  Congress  is  at  It  again.  This 
time  IheyYe  grabbing  25  MHz  of  one  of 
your  unused  UHF  barKJs  arxJ  putting  it 
up  for  auction,  with  tfi#  proceeds  to  90 
toward  supporting  even  more  Congres- 
sional pork.  They'll  get  billions  for  it. 

Our  2390*2450  MHz  band  is  the  first 
on  the  block,  with  recommendations  for 
selling  oft  the  2390-2400  and  2402- 
2417  segments.  They're  graciously 
planning  to  leave  us  the  2400-2402 
segment  tor  our  satellite  commumca' 
tions.  They've  also  targeted  2300-2310 
for  later  s^e.  Thatll  carve  35  MHz  from 
our  70  MHz  alkxation,  Half! 

tn  3  few  years  well  either  have  a 
healthy  amateur  radio  hobby  which  is 
largely  satellite  oriented  or  well  be  a 
vague  footnote  in  the  history  books. 
The  world  Is  going  high-speed  digital 
and  leaving  us  behind  in  the  dusL 

So  wt^at  can  you  do  dbo^rt  all  this? 
Prtibably  not  much.  Yov've  bet  the  farm 
on  the  ARRL  and  they  Ye  unlikely  to 
take  any  action  that  could  change 
things.  Congress  es  run  by  bnbes.  with 
the  biggest  bribes  going  to  the  subcom- 
mittee members.  Let  me  be  blunt 
...  how  much  money  have  you  person- 
ally donated  to  your  congressmen's  re- 
election fund?  rm  wiOirtg  to  bet  that  all 
500.000  Of  the  hams  who  may  Still  be 
alive  have  donated  well  under  S50^Q00. 
Ten  cents  a  head-  Wei  J.  a  dime  may 
have  been  big  money  when  old  man 
Rocketeiter  was  handing  'em  out  in  the 
1930s,  but  we  don't  even  txither  to  lean 
over  to  pick  up  a  dime  on  the  street 
these  days.  With  Congress  you  get 
what  you  pay  for  and  not  anything  ex- 
!ra.  They  know  you're  so  stupid  you  will 


continue  to  re-elect  them,  so  why 
sHoutel  they  care  wttat  you  think? 

Now.  if  you  could  sta/1  getting  sorrte 
petitions  going  among  your  family, 
friends  and  co*workers,  promising  to 
unelect  them  if  they  sell  off  your  her- 
itage of  ham  microwave  frequencies, 
we  might  get  somewhere.  It  would  take 
ham  clubs  in  all  50  states  to  puil  it  off. 
One  thing  you  can  bet  on.  I'll  be  watch- 
ing the  ham  club  newsletters,  looking 
for  some  signs  ttiat  someone  out  there 
gives  a  damn  about  the  hobby.  If  eveiy 
ham  club  in  the  country  started  getting 
petitions  signed,  with  copies  to  their 
congressmen  and  me ^  we  might  end  up 
with  bigger  satellite  bands  instead  of 
diced  and  sliced  babney. 

Or  you  can  wait  for  the  ARRL  to  do 
something,  which  1  doubt  will  ever  hap- 
pen. 

What  will  I  do  with  a  ton  of  petitions? 
I've  been  a  registered  Washington  lob- 
byist for  over  20  years  now.  so  I  know 
exactly  what  to  do.  I've  been  down 
there  before  waving  a  sheaf  of  petitions 
and  watched  the  reaction.  That  was 
what  got  us  the  hearing  before  the  FCC 
Commissioners  20  years  ago,  the  one 
which  resulted  in  the  biggest  changes 
in  ham  rules  in  the  history  of  the  hobby. 
That's  when  we  got  back  our  repealer 
lighls. 

Yes,  Congress  Is  njn  tiy  bribes,  but 
tfiey  also  am  influenced  by  cartons  of 
petitions.  Heavily  influenced.  If  they  get 
uneiected  they  re  suddenly  off  the  lob- 
byist gravy  train. 

But  heck,  it's  only  25  MHz  of  a  band 
we  aren't  using,  so  who  cares.  Right? 
Never  mind  that  the  camel's  nose  is  in 
the  tent 

Poor^  Dumb  Wayne 

A  few  years  ago  t  got  an  Interesting 
letter  from  George  W9EJY  proposing  a 
ridiculous  new  modulation  approach. 
Imagine  being  able  to  put  a  75  MHz  FM 
signal  out  on  an  AM  broadcast  trans* 
mitter!  An  obviously  crazy  idea. 

But  George  had  stirred  up  an  Idea 
f^d  had  years  before  ,  .  ,  an  idea  thai 
seemed  logical,  but  if  so,  why  wasn't  it 
being  used?  I  think  I  even  wrote  about 
this  in  an  editorial  mayb€  20  years  or 
so  ago.  So  I  ran  the  »dea  by  a  scientist 
thend  of  mine  to  see  if  he  could  shoot  it 
down.  He  hemmed  and  awed. 

What  George  has  done  . . .  what  Td 
wondered  about  years  ago  . . .  was  tak- 


ing an  audio  modulated  FM  signal  and 
divfdJng  it  down  Let's  say  you  want  to 
have  a  n«:e.  full  frequency  aucSo  signal. 
We  coufd  even  start  with  the  normal  75 
kHz  commercial  FM  bandwidth,  modu- 
lating it  at  100  MHz,  right  up  in  the  mid- 
dle of  the  FM  band.  Now  we  divide  rt  by 
5  twice  and  we've  got  a  4  MHz  signal 
with  3  kHz  bandwidth.  Any  reason  we 
can't  transmit  that  on  75m  and  have 
one  heck  of  an  FM  channel? 

To  receive  it  you'd  want  to  multipfy 
times  5  twk^.  This  woukj  take  your  455 
kHz  IF  signal  and  move  il  to  284.375 
MHz.  A  local  osciliator  at  273,675  MHz 
would  give  you  your  10,7  MHz  IF  signal 
for  any  FM  receiver  to  detect. 

Well,  if  we  can  do  that  lor  FM,  how 
about  a  6  MHz-wide  TV  signal?  Well 
we*d  have  to  start  at  around  2500  MHz 
ar>d  divkle  down  by  5  four  limes,  That 
would  again  give  us  a  4  MHz  output, 
but  with  ±9.6  kHz  of  modulation.  Not 
bad  for  ATV  on  75m,  eh? 

Now  please  tell  me  why  this  won't 
work.  Then  ill  pass  (he  word  to 
George,  who  has  tested  Ns  F1V1  idea  on 
the  air  with  a  cooperating  AM  broad- 
cast station  and  found  it  to  work  just 
fine.  He's  been  exhibiting  at  the  NAB 
conventions,  looking  for  a  sponsoring 
company  to  get  involved.  He's  found 
that  ff  the  AM  station  keeps  its  AM 
modulation  at  around  S5%  tfrere  is  no 
detectable  interference  between  the 
AM  signal  and  the  micro-mod ulated  FM 
signal  on  the  same  carrier. 

As  George  points  out.  the  exciters 
used  for  early  FM  transmitters  started 
out  at  around  115  kHz  with  ±87  Hz 
phase  modulation  and  then  multiplied 
that  up  864  Umes  to  the  output  channel, 
Sduce  for  the  goose . 

The  concept  was  good  enough  to 
gel  George  a  Technology  Award  from 
The  Society  of  Broadcast  Engineers  in 
1992.  But  is  it  enough  to  gel  you  to  give 
it  a  try? 

Progress 

5o  here  we  are  in  1 994.  And  hem  I 
am  using  a  Macintosh  PowerBooK  for 
most  ol  my  work.  And  here  I  am  without 
a  simple  program  to  keep  track  of  and 
display  the  sales  of  my  enterprises. 
This  is  ridiculous! 

The  first  practical  microcomputer 
was  the  Radio  Shack  TRS-80,  which 
debuted  In  August  1977,  just  two  years 
after  the  first  micro  was  announced. 


The  first  was  ttie  MITS  Aftair  8800.  but 
that  lacked  a  few  things.  It  came  in  kit 
form  and  had  no  operating  software  at 
all.  A  few  months  later  Bill  Gates 
showed  up  at  MITS  in  Albuquerque 
with  his  |ury-rlgged  BASIC,  The  way  \ 
recall  it.  he'd  written  a  BASIC  inter- 
preter for  the  0008  chip  as  an  exercise 
in  his  computer  course  at  Harvard. 
When  the  Altair  came  along,  desper- 
ately needing  sornething  to  make  tl  do 
more  Ihan  be  an  expensive  paper- 
weight, he  cobbled  h^  interpreter  so  rt 
would  work  on  the  8030  chip,  left 
school,  and  went  to  work  for  MITS. 
He's  doing  fairly  well. 

Commodore  came  out  with  a  PET 
microcomputer  in  around  March  1977. 
but  it  had  a  stupid  square  keyboard, 
and  a  marketing  plan  designed  to 
screw  any  dealers  who  sucked  into  try- 
ing to  sell  it.  My  recollectioo  is  that  Jack 
Tr^mJel,  the  president,  set  up  his  own 
separate  nnail  order  finm.  Contemporary 
Marketing,  in  Bensenville,  out  near 
Chicago,  just  to  sell  the  PETs.  He  re- 
fused to  let  Commodore  run  any  ads 
for  the  computer,  with  only  his  rrflii  or- 
der firm  advertising.  I  visited  the  factory 
in  California  where  1  was  told  that  only 
alter  his  mail  order  company  had  all  ttie 
Inventory  they  needed  would  Com- 
modore ship  any  units  to  dealers. 

But  to  use  the  PET  you  had  to  load 
BASIC  from  a  cassette,  and  so  on. 
Slow.  By  the  lime  Radio  Shack  an- 
nounced their  TRS-60  Model  I,  the  cus- 
tomers were  ready  for  It. 

I  realized  that  the  only  practical  way 
to  provide  Ihe  software  these  micro- 
computers were  goirig  to  need  was  to 
manufacture  and  sell  it  in  quantity.  Up 
until  then  we  had  the  mainframe  com- 
puters, starting  in  the  million-dollar 
range,  compiele  with  horrendously  ex- 
pensive software,  also  running  in  the 
million-dollar  range.  Then  came  the 
minicomputers  In  the  $100,000  bracket. 
The  software  for  these  systems  was 
custom -developed  for  each  user  and 
also  ran  around  $100,000  on  the  aver- 
age. So  I  figured  that  now  that  we  t^d 
$10,000  computer  systems  we  were 
going  to  have  to  get  soft- ware  costs 
down  too,  and  that  meant  mass  pro- 
duction. That's  when  I  started  Instant 
Software. 

My  approach  was  simple.  I  got  the 
readers  of  my  magazines  to  send  in 
software  ttiey'd  developed  for  possible 
dislnbutk»n.  I  set  up  a  lab  with  around 
30  work  stations  so  we  coukl  cover  the 
m.'^st  popular  micros.  Incoming  soft^ 
ware  was  then  evaluated  by  my  people 
and  the  best  of  it  was  put  into  shape  for 
production.  We  started  out  with  a  lunar 
lander,  and  went  on  to  develop  all  kinds 
of  games,  educational  stuff,  and  quite  a 
few  rather  good  business  programs. 
Our  Typing  Teacher  won  prices,  as  tfid 
our  geography  prograrrts^ 

One  of  ttve  best  was  Business  Anal- 
ysis, Though  that  was  designed  for  the 
Model  I.  and  later  it  was  updated  for  the 
Model  til.  II  was  so  far  beyond  anything 
Tve  seen  since  that  it  is  fnjstrating.  I 
sure  wish  something  like  that  was 
available  for  my  Mac.  If  there's  a  pro- 

Conttnued  on  page  74 


4  73 Amafsur  Radio  Today*  July,  1 994 


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Lehers 


Number  2  on  your  Feedback  card 


James  W.  Searcy  WA5WRE, 
Poplarville  MS  In  July  of  1992  there 
was  an  amateur  in  Picayune.  Missis- 
sippi, who  came  up  on  the  locaJ  re- 
peater there  and  used  at!  kinds  of  four- 
letter  words,  complaining  about  a  wom- 
an driver  cutting  him  off  in  traffic.  As  he 
was  spouting  off  over  the  air,  I  calied 
the  FCC  office  in  New  Orleans  and  iet 
an  FCC  engineer  listen  for  a  solid  five 
minutes.  He  toid  me  that  there  was 
nothing  the  FCC  could  do*  for  they 
could  not  "define"  wfiat  was  obscene. 
Well.  I  cHewed  thai,  and  after  choking  a 
few  times  I  managed  lo  swalfow  it 

Now  (April  1)  I've  had  a  non-ham 
come  up  on  my  machine  here  in 
Poptarville.  use  our  autopatch.  and 
never  sign.  We  caught  the  indFvidual. 
called  the  FCC.  taiked  to  t^^  ^me  en- 
gfneec  and  were  told.  There's  nothing 
we  can  do,  for  we  dEdn  t  witness  the 
QSO."  Not  only  that^  but  a  business 
wtiose  owner  is  an  Extra  Class  ama- 
teur sold  him  the  radio, 

Weil,  needless  to  say,  this  upset  me, 
but  what  really  hurts  is  tiiat  word  got 
out  about  the  FCC's  "non -action,-  and 
now  one  of  my  students  has  dropped 
out  of  class  and  is  operaiir>g  on  ama- 
teur frequenoes  with  a  bogus  caJi,  stat- 
ing. "Why  worry?  The  FCC  won^  do 
anything  to  you.  so  w?^y  go  tlirotigh  the 
Noodache  of  working  for  a  license?* 

IVe  been  an  an^atetrr  (or  42  yeers 
aftd  frankly,  Tve  reached  the  point 
where  I  cani  blame  him.  It's  like  goir>g 
to  a  war  without  your  leaders.  What  are 
you  supposed  to  do?  With  no  FCC 
backing,  there  is  no  chance  of  winning. 

I  don't  operate  HF  at  ail»  but  it  I  did  I 
think  I  would  modify  it  for  CB  so  tiiat 
wiien  the  lime  comes  11!  be  ready. 

James — You  haven't  t^een  reading 
my  editorials.  TsfL 

As  Vve  expfained.  the  FCC  is  under- 
staffed and  underpaid,  and  doesn't 
want  to  be  bothered  with  Mmateur  ra- 
dio, if  we  aggravate  them  very  much 
tt^yU  get  more  interested  in  ending  the 
hc^y  Aitef  all,  the  FCCpeopie  get  no 
Imrmftt  from  hams. 

Were  no  ion^r  ifving  tp  to  any  part 
Of  our  charter,  so  the  less  we  toother 
them,  tt^e  longer  well  be  able  to  use 
the  t)iftions  of  dollars  in  spectrum  we've 
inherited. 

The  fact  fs  that  when  there  is  a  focal 
problem  it's  up  to  the  iocal  amateurs  to 
take  the  soiution  of  the  problem  as 
their  responsibility  You  can't  expect  the 
FCC  to  spend  money  to  heip.  After  all, 
how  much  money  are  you  paying  for 
ywr  license?  Zilch.  And  what  etse  are 
you  contributing  to  the  commonweal? 
Not  very  mucit 

The  best  rule  is  not  to  poke  the  bear 
while  it's  sleeping. 

73..,  Wayne 

Itttvln  Elliott  K0VNP,  on  the  73 
BBS  Wayne,  I  wan!  to  thank  you  for  a 
few  of  the  tilings  you  have  unknowingly 
given  me.  You  and  your  mag,  In  the 
early  small -size  fomriat,  got  me  inter- 
ested in  ham  radio,  via  the  articles  and 


From  the  Ham  Shack 


your  grasp  of  the  ham  community.  You 
gave  me  the  chance  to  enter  through 
reading  t^e  various  articles  and,  of 
course,  your  comments. 

t  bought  your  lapes  in  1976  to  team 
lUorse  code.  You  had  a  rather  odd  idea 
of  sending  fast,  with  the  spacing  in  the 
range  needed.  With  me  it  was  5  WPM 
that  got  me  into  the  area  I  thought  1 
would  not  be  able  to  attain.  The  numer- 
ous magazines  that  my  Elmer  gave  me 
to  read,  yours  and  others,  were  what 
got  the  Iheory  lo  begin  to  make  a  bit  of 
sense.  But  no  matter  what  subject  t 
wanted  to  rind,  articfes  in  your  73  mag- 
azine were  what  I  came  back  to.  Your 
trips  and  DXpeditions  allowed  me  and 
otiiers  ttie  chance  to  see  what  tl^is  t\ob- 
byisallatXHJt 

I  went  on  to  get  my  General  ticket 
and  worked  about  175  countries.  Via 
moving  and  a  divorce  I  lost  about  all  of 
my  gear  and  my  QSL  cards.  I  lost 
yours  tn  a  fire,  and  that  was  probably 
one  of  the  most  treasured  of  the  bunch. 
I  had  the  early  Ciipperton.  Watvis  Bay^ 
on  the  second  day  they  used  that  call, 
and  others*  but  my  W2NSD/1;  card  was 
at  the  top  of  the  iisl.  You  were  nice 
enough  to  send  me  a  card  a  Few 
nnonihs  back  to  replace  the  one  I  lost, 
and  I  thank  you^ 

Last  Saturday  I  took  my  Advanced 
test,  which  I  passed  with  ease,  in  a 
large  pan  thanks  to  reading  and  leam- 
rng.  Even  at  age  41  my  dreams  contin- 
ue, thanks  to  your  magazine.  My  fr- 
cense  was  feinstated  from  my  tirsl  call 
(WB0YHG)  to  N0VNP  because  i 
strayed  from  the  hobby  that  I  have 
grown  to  fove.  But,  finding  your  bigger- 
size  magazine  on  the  newsstand  one 
day  about  two  years  ago  relit  the  fire 
that  i  hadn't  realized  had  gone  out* 

Wayne,  thanks  for  ttie  memories 
that  you  have  gtven  me  and  for  the  en* 
joynrieni  that  each  month  i  discover  in 
the  pages  of  your  publication,  Dont 
change  now — I'm  too  old  to  be  con- 
fused. 

By  the  way.  I  am  getting  remarried 
on  August  6  and  my  future  bride  will  be 
3  ham  by  then  as  welL  Sne  is  taking 
her  Tech  (with  code)  class  from  a  local 
group,  and  in  large  pait  I  can  thank  you 
for  that  as  well.  Your  edilonals  aboul 
education  have  a  very  speaiat  meaning 
to  us.  May  ali  your  skip  be  long  and  the 
scuba  diving  safe. 

Gary  Moeller  N8WVV,  from  the  73 
BBS  I  love  your  editorials.  They  are 
one  of  the  first  things  I  read  each 
month  when  I  get  my  copy  of  73. 
Please  keep  prodding  us — heaven 
knows,  we  need  someone  to  keep  us 
thinkir>g.  The  rest  of  society  seems  to 
want  us  to  go  brain  dead  ar>d  you  are 
hejipir>g  to  keep  us  alive. 

(rving  L  Chidsey,  Havre  de  Grace 
MO  Wayne.  I  was  peoising  my  son's 
copy  of  the  Apnl  issue  of  73  and  f>oted 
your  column  on  "Good  Science  and 
Bad  Science."  The  quality  of  what 
passes  for  science  in  public  discussion 
has  long  been  a  concern  of  mine.  I  am 


gtad  to  know  thai  it  ts  also  a  concem  oF 
yours,  but  I  am  puzzled  by  your  choice 
of  examples,  for  we  seem  to  be  on  op* 
posiie  sides  of  several  issues,  and  i 
would  like  to  know  what  your  criteria 
were.  For  most  of  iny  professional  ca- 
reer I  was  part  of  the  Bockel/Upper  At- 
nrtosphere  program  at  the  Army's  Bal- 
listic Research  Laboratory,  classified  as 
a  physicist*  or  a  research  scientist,  or  a 
research  engineer  at  the  whim  of  the 
personnel  office.  My  criteria  are  that  as 
much  as  possible  I  check  with  the  ref- 
er eed  journals  (more  difficult  since  I  fe- 
ll red  two  years  ago),  and  that  \  under- 
stand the  underlying  science.  Now  that 
I  can  no  longer  easily  read  refereed 
journals,  t  use  The  American  Scientist, 
publistied  by  Ssgma  Chi,  The  Scientific 
American,  Science,  and  Nature  when  1 
can  get  them,  and  books  published  by 
recognized  scientists.  I  don't  own  a 
copy  of  Corn's  booK  but  if  I  c£d,  I  woukf 
read  it  to  check  hjs  understanding  of 
the  Issues,  not  to  inpmve  mine. 

My  reading  of  the  sctentifK:  joumals 
tells  me  that  scientist  are  worried 
about  acid  rain  and  rts  effects  on  the 
more  fragile  ecosystems.  The  first  arti- 
cles about  the  increase  in  atmospherio 
CO^  appeared  in  the  Journal  of  Geo- 
physical Research,  etc.,  during  the  mid 
'60s.  and  scientists  have  been  con- 
cerned about  the  probable  conse- 
quences, -giobal  warming  and  a  rise  in 
the  sea  level,  since  the  earty  70s.  It 
was  also  the  scientists  who  discovered 
the  ozone  hole  over  the  South  Pole, 
and  they  have  made  great  strides  in 
understanding  what  causes  it  The  at- 
mospheric science  community  StitI  be- 
lieves that  a  nuclear  winter  was  the  ex- 
pected aftermath  of  an  all-out  nuclear 
exchange  between  the  United  States 
and  the  USSR-  Frankty,  t*m  qyite  happy 
that  we  didn't  try  that  experiment.  After 
the  Gulf  War,  one  very  earnest,  very 
prolific,  and  very  wrong  nut  flooded 
several  discussion  groups  on  the  Inter* 
net  with  predictions  of  doom  because 
they  thought  the  very  extensive  smoke 
clouds  from  the  burning  oii  fields  would 
cause  a  Gulf  War  winter  There  was  a 
quite  measurable  cooling  where  the 
ctoods  persisted,  about  what  the  ttieory 
predicted,  but  it  went  away  when  the 
fires  stopped.  To  that  extent  the  nucle- 
ar Winter  theory  has  been  validated 

Yoor  ottier  examples  are  from  fields 
lurttier  from  my  expertise,  but  I  believe 
that  nrx^si  of  them  are  valid  concerns.  I 
agree  that  the  Alar  scare  was  a  panic 
attack  that  grew  because  the  scientists 
hadn't  done  theif  research  yet  It  is  true 
that  we  won't  run  out  of  oil  'til  quite 
awhile  after  the  turn  of  the  century,  but 
we  now  have  to  do  much  of  our  drilling 
in  very  dangerous  and  inhospitable 
places,  and  it  is  getting  harder  and 
harder  to  find  major  oil  fields.  We  are 
losing  topsoii  and  we  are  paving  over, 
or  developing,  much  of  our  best  crop- 
land: the  county  I  live  tn  has  Ic^t  over 
half  its  farmland  to  development  in  the 
last  40  years.  There  are  areas  m  our 
country  where  the  water  table  has 
dropped  several  hunched  feet  ove^  ttie 
last  few  decades-  The  example  that 
comes  to  mind  is  the  OgalJala  aquifer 
in  the  Rams  states:  on  Long  Island, 
sea  water  has  moved  in  to  replace 
potable  ground  water.  ( think  that  such 
examples  can  be  reasonably  described 
as  using  up  our  ground  water. 


Some  other  examples  of  bad  sci- 
ence. Of  at  least  prematurely  an- 
nounced science  that  didn't  pan  out. 
ai^  the  4th  state  of  water,  cold  fusion, 
unlimited  oil,  and  laetrile.  Several  of 
them  were  trumpeted  by  the  press  be- 
fore they  had  gone  through  the  scientif- 
ic review  process  Unfortunately,  the 
loudest  protagonists  on  both  sides  of 
these  questions  tend  to  be  the  most  ir* 
responsible,  and  the  scientists  may  be 
left  out  of  the  public  discussion. 

Remember,  we  do  our  science  out 
In  the  open,  and  In  some  cases  the  sci- 
ence gets  communicated  to  the  public 
while  it  is  still  being  baked:  the  press 
likes  to  get  its  stories  while  they  are  still 
hot,  without  waiting  for  all  questions  to 
be  threshed  out  In  the  review  process. 
In  several  of  these  cases,  the  news 
was  published  too  soon;  the  "good  sto- 
ry* was  a  false  lead,  an  emor  which  the 
scientific  oonmrtunity  corrected  as  soon 
as  it  could.  Ttie  alternative  is  to  study 
the  phenomena  in  secret,  and  only  in- 
form the  public  when  all  the  research  is 
done  and  all  doubts  removed.  I  don't 
think  thai  secret  science  is  either  possi- 
ble Of  desirable  in  a  tree  society,  and 
you  would  be  among  the  first  to  obj:ect 
if  it  were  tried.  Absent  carefully-con- 
trolled release  of  only  assured  results^ 
we  have  to  let  the  work  in  progress 
hang  out  in  public  and  take  our 
chances  that  the  public  will  some!inr>es 
be  led  astray.  Again,  I  would  like  to 
know  what  your  criteria  were  for  choos- 
ing your  examples  so  I  n\ay  understand 
why  we  ditfef. 

Irving — Yes.  we  do  differ  But  if  yott 
ck>  some  homework.  I  think  we  7/  be  *? 
agreement.  I  suggest  you  read  Envi- 
ronmental Overkiil  by  Dixie  Lee  Ray. 
the  former  Governor  of  Washington 
and  Chairman  of  the  Atomic  Energy 
Commission,  Assistant  Secretary  of 
State,  etc.  The  publisher  is  Rsgnery 
Gateway  Commission,  $20,  260  p. 
Then  read  Ecoscam  by  Ronald  Bailey, 
St  f\^artin's  Press,  228 p. 

These  two  books,  ptus  several  oih' 
ers  I've  read,  alt  agree  that  the  ozone 
hole  is  baloney  and  ditto  global  warm- 
ing and  the  coming  ice  age.  Even  the 
nuc^ar  winter  data  has  tte^n  seriously 
challenged  in  Scientific  American,  a$ 
has  acid  ratn.  Ray  demolishes  that 
tMi^too.  too  (pages  147-150}. 

Remember  that  no  sclenfific  issue 
can  be  resolved  by  strongty-hetd 
belief,  no  matter  how  eminent  the 
authority. 

Ymj  are  ir\deed  out  of  touch  when  it 
comes  to  cold  f us  ton.  Tsk!  The  pre- 
miere issue  o/"CoEd  Fusion"  magazine 
is  in  my  hands:  100  pages,  with  articles 
by  several  well-known  scientists. 
CopiGS  of  the  magazine  are  $W,  If 
you're  interested  in  coming  up  to  speed 
on  something  you  believe  didn't  'pan 
out" 

You  mentioned  Laetrile,  which 
makes  me  wonder  how  much  you've 
read  about  it.  Not  much.  Ill  i?ef.  How 
a£x>ut  what  the  AMA  did  to  t-loxsey  and 
to  Krebiozen?  You  11  want  to  read 
Racketeering  In  Medicme.  The  Sup- 
pression of  Alternatives  by  Dr.  Carter, 
Hampton  Roads  Press.  Si 3.  360  p. 
Goodt^x>h. 

You  also  might  read  fmpure  Science 
by  Bell,  Wiley  $23,  300  p.  Cheers  .^^ 
Wayne 


5  73  Amateur  Radio  Today  •  July,  1 994 


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Number  3  on  your  Feedback  c^rd 


FCC  Amends  Message 
Forwarding  Rules 

The  Federal  Communications  Commission 
has  acted  on  RR.  Docket  93-85  and  has  re- 
laxed the  Amateur  Service  rules  lo  enable 
conteniporary  mes&ag©  forwarding  systems  to 
operate  at  hundreds  of  characters  per  second 
while  retaining  safeguards  to  prevent  misuse. 

A  message  forwarding  system  is  a  group  of 
amateur  stations  participating  in  a  voluntary, 
cooperative,  interactive  arrangement  where 
communications  from  the  control  operator  of 
an  originating  station  are  transmitted  to  one  or 
more  destination  stations  via  forwarding  sta- 
tions, which  may  or  may  not  be  automatically 
controlled. 

Currently,  the  control  operator  of  each  sta- 
tion is  held  individually  accountable  for  each 
message  retransmitted,  resulting  in  unneces- 
sary content  review  and  delays.  The  Ameri- 
can Radio  Relay  League  stated  that  the  obli- 
gation of  the  control  operator  of  the  first  for- 
warding  station  should  be  the  establishment 
of  the  identity  ot  the  station  originating  the 
message.  Only  when  this  is  not  done  should 
these  control  operators  be  held  accountable 
for  improper  message  content. 

The  commission  agreed,  and  thus,  the  FCC 
will  hold  accountable  only  the  licensee  of  the 
station  originating  a  message  and  the  li- 
censee of  the  first  station  forwarding  a  mes- 
sage in  a  high-speed  message  forwarding 
system-  The  licensee  of  the  first  forwarding 
station  must  either  authenticate  the  identity  of 
the  station  from  which  it  accepts  communica- 
tions on  behalf  of  the  systenv.  or  accept  ac- 
countability for  the  content  of  the  message. 
T7VX  Westlink  Report.  No.  670,  April  21,  1994. 


See  The  Light 


A  young  Missouri  company  has  announced 
what  they  say  is  the  ftrst  fiber  optic  cable  sys- 
tem for  home  audio  and  video  application.  De- 
velopers hope  the  Mor}goose  cable  system 
will  soon  replace  conventional  wire  cables 
carrying  high-fidelity  analog  signals  in  runs  of 
up  to  2.4  miles- 

Why  bother?  According  to  a  company  vice 
president,  ft  is  the  best  way  to  connect  both 
audio  and  video  components,  "It  is  non-con- 
ductive, has  no  impedance,  and  neither  caus- 
es nor  attracts  electrical  noise."  VP.  of  Devel- 
opment of  ASM  Labs  Armando  Martinez  fore- 
sees market  demand  from  twth  amateur  and 
professional  audio  and  video  purists.  The  in- 
tegrity of  the  original  signal  is  uncompro- 
mised."  says  Martinez,  adding  that  this  is  the 
first  fiber  optic  system  that  is  plug-compatible 
with  conventional  equipment. 


New  kHz  on  the  Block 

The  Federal  Communications  Commission 
will  hold  frequency  spectrum  auctions  this 
fall,  according  to  Chairman  Reed  HundT.  The 
frequencies  heading  for  the  auction  block  are 
to  be  used  to  expand  mobile  communica- 
tions, which  Hundt  says  has  the  potential  to 
become  one  of  the  country's  largest  indus- 
tries by  the  end  of  the  canary,  wittx  at  least 
87  million  customers. 

Hundt  also  says  he  wants  the  FCC  to  pro^ 
mote  competition  in  the  communications  m- 
dustry,  especially  for  cable  TV,  so  rate  reguia- 
tfon  can  eventually  be  eltmlnated.  TNX  West- 
link  Report,  No,  671,  April  30,  1994, 


Brain  Cells 


Energizer  Power  Systems  and  National 
Semiconductor  Corp.  have  developed  a  new 
battery  that  monitors  its  own  power  consump- 
tion and  provides  recharging  communications 
with  the  host  equipment  These  "smart  batter- 
ies'' are  expected  to  firs!  appear  in  notetKx>k 
computer  applications. 

The  new  batteries  use  nickel-metal-hydride 
and  nickel-cadmium  rechargeable  cells.  The 
intemal  brains  virtually  prevent  overcharging 
and  allow  for  useful  'lime-lefT  or  **%  capacity 
remaining"  information  to  display  on  the  host 
device. 

The  announcement  comes  at  a  time  when 
portable  electronics  equipment  use  is  sky- 
rocketing. Duracell  International  and  Intel 
Corp.  have  also  joined  together  to  develop  a 
smart  battery  of  their  own.  TNX  Etectronic 
Engineering  Tunes,  Issue  797,  May  16,  1994. 

FCC  Cracks  Whip 

Fifty-nine  Southern  California  hams  are 
under  order  from  the  Federal  Communica- 
tions Commission  to  retake  their  amateur  ra- 
dio license  exams  or  face  penalties*  accord- 
ing to  a  story  in  the  Westlink  Report.  The 
commission  says  all  of  the  licensees  in  ques- 
tion were  passed  at  sessions  conducted  by 
the  ARRL-VEC  In  1992  and  1993.  Those  vol- 
unteer examiners  are  also  facing  government 
scrutiny. 

In  a  letter  sent  to  those  licensees,  the  FCC 
fiatly  accused  the  applicants  of  cheating.  The 
letter  says,  *" ...  the  irregularities  on  your  ex- 
amtnation  papers  indicate  that  you  were  ap- 
parently given  access  to  the  exact  (answer) 
key  used  by  the  volunteer  examiners.* 

Those  who  were  passed  at  the  suspect 
testing  sessions  have  60  days  to  retest. 
Those  who  fail  would  face  downgrade  or  loss 
of  license  entirely.  Refusing  to  retest  could  re- 
sult in  more  severe  penalties.  So  far,  almost 


three  d03:©n  VEs  have  been  suspended  tn 
Southern  California,  in  connection  with  test- 
ing irregularities,  under  orders  of  the  FCC. 
TNX  Westlink  Report,  No.  671,  April  30, 
1994. 

What's  Your  $ign? 

The  callsign  of  your  dreams  awaits  you, 
and  the  price  will  be  S7.  Thafs  the  word  from 
the  Federal  Communications  Commission. 
On  March  11,  ttie  FCC  released  its  Notice  of 
Proposed  Rule  Making  to  implement  the  new 
fee  assessments  for  licensees  who  were  au- 
thorized by  the  1993  US  Budget  Ad. 

Item  69  of  the  NPRM  notes  fees  for  ama- 
teur 'Vanity"  callsigns.  that  are  to  take  effect 
whenever  the  commission's  proposal  is  finally 
approved.  The  current  plan  calls  for  a  fee  of 
$70,  or  $7  per  year  for  the  10-year  license 
term.  TNX  Westlink  Report.  No.  671,  April  30, 
1994. 


Top  Cop 


According  to  Electronic  Engineering  Times, 
a  group  of  students  at  the  Massachusetts  In- 
stitute of  Technology  recently  showed  they 
were  "complete  engineers'*  by  arranging  a 
rather  sophisticated  end-of-semester  prank. 
The  article  quotes  Bob  Rivers,  Human  Re- 
source Director  at  Bose  Corp-^  saying  the 
MIT  students  displayed  a  number  of  desirable 
qualities  his  company  looks  for  when  hiring 
engineers:  initiative,  leadership,  technical 
knowledge,  planning  and  organization,  and 
the  ability  to  handle  stress. 

So,  what  did  the  students  do?  They  some- 
how constructed  an  exact  replica  of  a  cam- 
pus police  car — right  down  to  a  bag  of  Dunkin 
Donuts— and  lifted  it  to  the  dome  of  one  of 
MITs  main  buildings,  all  in  complete  secrecy. 
As  you  can  Imagine,  the  story  was  highly 
photographable^  and  made  all  the  evening 
newscasts  in  Boston.  Rivers  says  these 
young  engineers  also  have  another  trait  that 
is  very  desirable  in  the  workplace — a  sense 
of  humor.  TNX  Electronic  Engineering  Times, 
Issue  797,  May  16,  1994. 


TNX .  ■  ■ 


.  -  .  to  all  our  contributors!  You  can  reach 
us  by  phone  at  (603)  924-0058.  or  by  mail  at 
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items  by  FAX  at  (603)  924-9327. 


8  73  Amateur  Radio  Today  •  July,  1 994 


With  Packet  Transmission 


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Number  4  ofi  your  Feedback  card 


The  Global  Positioning  System 


An  overview. 

by  Bill  C[arke  WA4BLC 


The  NAVSTAR  Global  Positioning  Sys- 
tem, generally  called  GPS.  is  a  satellite 
mdio  posiiioning  network  providing  ver\^  ac- 
curate position,  velocity,  and  time  informa- 
tion. Although  GPS,  developed  by  the  U,S. 
Department  of  Defense  (DOD),  can  provide 
three-dimensional  position,  velocity  determi- 
nation^ and  pnecihiion  time  transfer,  position 
information  is  the  most  sought-  Plans  call  for 
GPS  to  be  the  DOD*s  primary  means  of  ra- 
dionavigation.  The  system  is  capable  of 
serving  an  unlimited  number  of  users  any- 
where on  the  ground,  at  sea,  in  the  air,  and  in 
near  space. 

Parts  of  GPS 

GPS  is  comprised  of  three  parts 
(officially  called  segments): 
space,  control,  and  usen 

The  space  segment  is  a  constel- 
lation of  24  satellites  in  semi -syn- 
chronous orbits  at  an  altitude  of 
20.200  km  (10.900  miles). 

The  control  segment  consists  of 
a  master  control  station  located  in 
Colorado,  and  five  monitor  sta- 
tions (MS)  situated  around  the 
world.  As  the  central  GPS  pro- 
cessing facility,  the  control  seg- 
ment is  tasked  with  tracking,  mon- 
itoring, and  managing  the  satellite 
constellation. 

The  user  segment  consists  of 
the  consumers  of  GPS,  They  may 
be  miliiary  or  civilian;  however, 
all  must  be  properly  equipped 
with  specially  designed  receiving 
equipment,  normally  referred  to  as 
a  GPS  receiver  or  receiver/proces- 
sor, to  make  use  of  GPS. 

How  GPS  Works 

GPS  position  determination  is 
based  on  a  concept  called  time  of 
arrival  (TO A)  ranging,  which  is 
merely  the  signal's  travel  time 
from  transmission  to  reception. 

A  simple  example  of  TOA 
ranging:  The  distance  from  a 
thunderstorm  to  your  location  can 
be  figured  by  counting  the  sec- 
onds between  a  lightning  flash 
and  die  thunder  report  (the  TOA 
value).  Multiply  the  TOA  value 


by  0.2  (the  approximate  speed  of  sound  is 
two  tenths  of  a  mile  per  second)  to  calculate 
the  range  in  miles. 

The  NAVSTAR  satellites  are  broadcast 
beacons  transmitting  L-band  signals  consist- 
ing of  pseudorandom  noise  (PRNi.  The  PRN 
is  predetermined  strings  of  one  and  zero  da- 
ta bits,  generated  by  an  on-board  clock  that 
also  provides  the  exact  transmit  time  of  the 
signals.  GPS  satellites  transmit  spread  spec- 
trum signals  on  iwo  frequencies;  LI  = 
1575.42  MHz  and  L2  =  1227.6  MHz.  All  ra- 
dio transmissions  are  on  the  same  frequen- 
cies, with  individual  satellite  tdentification 


Photo  A,  The  Trimble  Navigaiton  SCOLT  GPS  receiver  (couriesy 
ofTnmhie  Navigation,  9020-11  Capitol  of  Texas  Highvav  North, 

Suite  400^  Austin  TX  78759: 800-959-9567 }, 

10  73  Amateur  Radio  Today  *  July.  1 994 


made  via  unique  individual  code  sequences. 

When  the  GPS  receiver  begins  tracking 
the  PRN  sequences  from  four  satellites  (the 
generally  accepted  minimum  number  re- 
quired to  proxide  adequate  accuracy),  the  re- 
ceiver's data  processor  rakes  oven 

The  processor  samples  the  receiver's  TOA 
values,  makes  numerous  calculations  and 
corrections  that  account  for  clock  errors, 
ionospheric  signal  delays,  receiver  noise,  etc. 
Much  of  the  corrective  mathematics  used  in 
these  calculations  is  variable  from  time  to 
time.  The  variables  are  provided  to  the  GPS 
recei%^er  as  parts  of  the  satellite  signal  called 
the  navigation  message  (NAV 
Msg), 

The  NAV-msg  is  superimposed 
on  the  satellite  signals  and  contains: 
GPS  system  time  of  transmission,  a 
hand-over  word  (HOW),  orbital  po- 
sition data,  clock  data,  and  almanac 
data  for  the  remaining  satellites  in 
the  constellation.  The  coefficients 
for  calculating  UTC  and  the  iono- 
spheric delay  are  also  included  in 
the  NAV-Msg. 

The  GPS  receiver  computes  the 
position  fix  in  coordinate  terms, 
consisting  of  latitude,  longitude, 
and  altitude. 

Note:  A  GPS  position  fix  refers 
to  the  electrical  phase  center  of  the 
receiver's  antenna,  as  the  antenna  is 
die  actual  point  of  signal  reception. 
The  normal  tracking  sequence 
begins  with  the  receiver  determin- 
ing which  satellites  are  visible  for 
tracking,  via  user-entered  predic- 
tions or  stored  satellite  almanac  in- 
formation from  previous  NAV-Msg 
data.  If  there  is  no  almanac  infor- 
mation.  a  search  of  the  sky  must  be 
made  to  locate  and  lock  onto  a 
satellite.  The  receiver  can  then  read 
the  NAV-msg  and  get  current  al- 
manac information  about  the  other 
constellation  satellites.  This  may 
sound  rather  complicated;  how^ever, 
the  user  can  relax  as  the  entire  pro- 
cess is  done  automatically  by  the 
rece  i  ve  r/proce  ssor. 

[f's  interesting  to  note  that  the 
typical  satellite  received  signal  lev- 
el is  below  the  earth's  natural  radio 


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f  44/440  MHz  flexible  ducks  far  HTs 

A.  High  Gain  FkxiDuck", 
fFJ-1717,  $19,95.  Enjoy 
spendable  QSOs  when  other 
ibber  ducks  give  you  noise, 
igh  gain  V2  wave  on  440  MHz 
ill  si^e  V4  wave  on  2M.  Won't 
b  you  --  bends,  twists,  flexes 
ith  you,  15^/4  inches.  _ 

B.  FlexiDuck^,  MFJ-Hlfi,  A.     B, 
16,95.  Similar  to  MFJ- 17 17.  Full  '/< 
ave  on  440  MHz,  efficient  loaded  V-i 
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Tnal!  Impedance  matched  for  maximum 
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5  elements  on  440  MHz,  -  -  4  elements  on  2  Meters . .  -$49.95 

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one  . , .  enjoy  two  Yagis  in  the  ^49*^ 

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Mounts  vertically  for  FM/Packet  or  horizontally  for  SSB  with 
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Partabim  Z  element  Yqqi  fer  2 

^SoM^       You  can  set  up  or  take  down  MFJ's 

39      portable  3  elements  2  Meter  Yagi  in 
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You  can  take  it  with  you  wherever  you  go  and 
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Mounts  vertically  for  FM/packet  or  horizontally  for  SSB.  Center 
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SWR  . . .  Strong  lightweight  aluminum 
construction  that's  protected  by  MFJ's  Permanent 
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power  , . .  MFJ's  RapidTune'^  radiator  for  quick 
acctirate  tuning  . . .  super  easy  installation  to  any 
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MFJ^17S2,  $19.95,  for  220  MHz  band 

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Mobile  Antenna  for  144/440  MHz 
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Opo^teboth  144 
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eain  on  440  MHz  with  a  Vi  wave  over 
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An  extra  powerful  magnet  holds  it 
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Use  it  with  mobiles  and  handhcldsf 

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Telescoping  antennas  for  handheids 

A.  Lang  Ranger^  2  Meter  Halfwave, 
MFJ47H  $16,95.  For  lually  long  range 
this  MFJ  endfed  halfwaw  is  hard  To  beat 
li  outpeiforms  a  V*  wave  on  a  handheld 
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noise  leveL    After  detection,  the  satellite's 

sigmil  is  multiplied  hy  use  of  receiver-pre- 
dicted PRN  codes  and  with  ihc  received  sig- 
nal collapsed  into  the  originiil  carrier  fre- 
quency band,  concenirated.  anti  brought  well 
above  ihe  natural  noise  leveL 

Simpiv  CmnplesL 

The  average  GPS  portable  receiver  some- 
what resenibles  a  VHP  handheld  transceiv- 
er in  size  and  weight.  Functionally,  you  will 
find  the  GPS  receiver  simpler  lo  opemie,  al- 
though somewhat  similar  in  flavor.  Buttons 
operate  selection  menus  and  functions  are 
selected  from  those  menus.  Ret^tring  to  the 
Trimble  Navigation  SCOUT  GPS  Receiver 
in  Photo  A.  ntjle  there  are  only  eight  buttons 
for  control.  By  using  the  builons  and  the 
scrolled  menus  appearing  on  the  LCD  dis- 
play, the  exact  location  can  be  determined, 
routes  may  be  programmed,  locations  mem- 
ori/ed,  distance  from  previous  or  input  loca- 
tions computed,  and  speed  calculat- 
ed. 


(rarely  ai^  complexities  a  user  concern  as 
most  GPS  receivers  are  designed  for  ease  of 
operation).  The  types  of  receivers  consist  of: 

Sequencing — ^This  ty^pe  tnakes  use  of  one 
or  two  hardware  (RF)  channels  by  simple 
stepping  from  one  seSected  satellite  to  anoth- 
er on  a  timed  basis.  Sequencing  receivers 
use  simple  circuitiy*  and  have  low  produc- 
tion costs  and  low  power  consumption.  They 
are  adequate  for  most  piiqioses  except  high- 
speed navigation. 

Continuous  tracking — These  have  a  mini- 
mum of  four  hardware  (RF)  channels  and 
track  four  or  more  satellite's  ^imuhaneously. 
They  are  less  affected  by  speed  ttian  the  se- 
quencing  receiver. 

Muhlplex  (MUX}— ^\i\i  this  type,  a  sin- 
gle hardware  (RF)  channel  is  switched  at  a 
fast  rate  between  satellites  being  tracked. 
Switching  is  typically  50  times  a  second. 
The  multiplex  receiver  is  based  on  time 
sharing  and  requires  only  a  single  code  gen- 


GPS  Accuracy 


GPS  was  designed  to  suppon  a 

broad  spectrum  of  users  with  differ- 
ing requirements  of  accuracy.  Basi- 
cally, there  are  two  categories  of  GPS    ._^_ 
accuracy  service: 

The  PPS,  precise  positioning  service, 
which  is  extremelv  accurate  and  available 
for  use  only  to  those  authorized,  and  the 
SFS,  standard  positioning  service,  a  less  ac- 
curate positioning  service  which  is  available 
to  all  GPS  users.  PPS  and  SPS  are  function- 
ally identical:  however,  access  to  the  PPS  is 
limited  by  encryption  techniques. 

PPS»  primarily  intended  for  mililary  pur- 
poses, typically  provides  accuracy  of  22  me- 
ters horizontally.  27.7  meters  vertically,  and 
time  within  90  nanoseconds. 

SPS,  used  for  civilian  purposes,  is  speci- 
fied to  provide  100  meter  horizontal,  300 
meter  vertical,  and  1 70  nanosecond  time  ac- 
curacy. The  horizontal  specification  includes 
peacetime  degradation  of  selective  availabil- 
ity (lI  means  of  tinkering  with  the  system  to 
make  it  less  accurate  in  the  name  of  national 
security).  For  the  SPS  user,  selective  avail- 
ability t^  the  dominant  SPS  accuracy  error 
source. 

In  practice,  the  spec ificut ions  are  easOy 
attained,  with  mucli  greater  accuracy  the 
rule  and  not  the  exception, 

GPS  Receivers 

Although  the  technology  of  GPS  is  fasci^ 
nating,  it  is  not  feasible  for  the  average  ham 
to  construct  a  GPS  receiver.  Not  that  some 
hams  aren't  capable  of  the  job — it  just  isn't 
feasible  (read:  worthwhile).  No  more  so  than 
building  a  2  meter  HT  with  all  the  current 
bells  and  whistles  would  be. 

There  arc  several  types  of  baste  GPS  re- 
ceivers, vaxy  ing  in  complexity,  tracking  ca- 
pabilities,  speed  of  information  update,  and 
planned  use.  Unfortunately,  corporate  mar- 
ket] ns  has  clouded  the  identitv  of  some  re- 
ceiver  types  and  operational  complexities 


^Wow  that  you  have  been  boggled 
by  the  high-tech  world  of  GPS ^  you 
might  ask^  ^Whafs  in  it  for  me?^'* 


erator  and  carrier  synthesizer  for  tracking. 

Digital — This  type  uses  analog-to-<iigital 
conversion  techniques  with  a  single  receiver 
IF  for  signal  amplification.  Signal  process- 
ing is  accomplished  digitally.  This  type  of 
receiver  can  be  visualized  as  a  single  chan- 
nel radio  iiecei\  er  with  five  digital  chajinels, 
each  monitoring  an  individual  satellite. 

Hams  and  GPS 

Now  that  you  have  been  boggled  by  the 
high-tech  world  of  GPS.  you  might  ask, 
"What's  in  it  for  mc?" 

Using  GPS,  a  ham  can  display  his  exact 
location  and  figure  distances  to  other  loca- 
tions. Other  locations  might  include  previ- 
ously *meniori  zed  points  (locations  electroni- 
cally in  the  receiver)  or  latitude  and  longi* 
tude  points  entered  manually. 

The  exact  location  of  VHF/UHF  repeaters 
can  be  determined  for  ease  of  mapping 
planned  coverage  and  determination  of  po- 
tential interference  with  existing  repeaters. 
As  the  GPS  is  a  three-dimensional  system, 
altitude  can  also  be  displayed. 

Distance  between  known  points  can  easily 
t)e  displayed.  Just  push  a  couple  of  buttons 
and  indicate  the  points  to  be  referenced* 
Again  1.  for  repealer  usage,  coverage  could  be 
determined  by  following  a  line  of  signal 
strength  and  niurking  locations  on  a  map. 
Distance  calculations  can  be  very  important 
for  mountatntop  VHF/UHF  operations. 

The  Maidenhead  grid  locator  system  (grid 
squares)  is  programmed  into  the  SCOUT 
GPS  receiver  and  indicates  grid  squares  to 
about  75- foot  accuracy.  The  display  consists 
of  the  basic  field,  square,  subsquare,  and  the 
TGL  (Trimble  Grid  Localor);  CM  87  XI  42 
LF,  which  corresponds  to  latitude/longitude 


of  37  degrees  20  minutes  33-0  seconds 

North/122  degrees  2  minutes  46.8  seconds 
West. 

Many  hams  find  themselves  involved 
with  search  and  rescue  duties,  whether 
through  the  Civil  Air  Patrol  or  other  public 
service  agencies.  Using  GPS  for  precise  po- 
sitioning, coverage  of  search  areas  is  very 
accurate  and  efficient,  leaving  no  area  over- 
lapped or  uncovered.  GPS  receiver  readings 
can  be  directly  applied  to  maps,  and  map- 
ploned  positions  quickly  located. 

WTiere  ts  GPS  Going? 

Although  initially  designed  for  militaiy 
usage*  the  civilian  world  has  discovered 
GPS.  No  doubi  the  system's  user  simplicity, 
accuracy,  and  reliability  factors  have  accel- 
erated its  acceptance.  It  is  safe  to  say  that 
GPS  wilL  at  some  point  in  the  future,  direct- 
ly impact  nearly  everyone. 
The  military  uses  OPS  for  aviation,  ma- 
rine, and  lami  navigation.  Examples 
include:  aircraft  instrument  liindings 
and  carrier  landings,  rendezvous 
such  as  irinighi  refueling,  improved 
bombing  accuracy  and  ballistic 
weapon  delivery  (smart  bombs), 
close  air  support,  reconnaissance 
^_^_     and  target  location,  enhanced  site 
surveying  and  field  artillery  place- 
ment. Insertion  and  extraction  missions  may 
be  carried  out  with  extreme  accuracy  (with 
safe  and  timely  deployment  and  evacuation 
of  troops)^  including  niedi-vac. 

GPS  was  used  during  Operation  Desert 
Storm  for  land  navigatitin  in  the  desert  areas 
where  maps  of  the  deserts  were  virtually 
non-existent  and  desen  physical/geographi- 
ca!  reference  points  wens  scarce. 

Marine  navigation  becomes  very  simple 
using  GPS  and  harbor  navigation  accuracy 
will  be  greatly  improved  over  current  meth- 
ods* Waterway  and  other  mapping  becomes 
as  simple  as  pushing  a  few  mcmor\'  buttons 
while  over-nying  or  otherwise  crossing  an 
area.  Later  memory  examination  allows 
maps  to  be  drawn. 

For  civilian  purposes,  the  applications  for 
GPS  appear  to  be  without  limit.  More  and 
more  uses  are  being  found  all  tlie  time,  in- 
cluding: 

Replacement  of  the  various  radio-based 
aviation  and  marine  navigation  systems. 

Creation  of  a  differential  GPS  (0GPS) 
system  to  increase  the  positioning  accuracy 
to  about  10  meters  (39  ft),  DCPS  only  re- 
quires that  a  local  positioning  signal  be 
added  to  the  mix  of  calculations  made  b}  the 
GPS  receiver. 

An  ambitious  projected  application  for 
GPS  is  Intelligent  Vehicle  Highway  System 
(IVHS)  technology.  IVHS  is  planned  for 
limited  use  in  the  year  2000.  Nearly  a  billion 
dollars  has  already  been  spent  or  allocated 
for  its  development  and  implementation. 
IVHS  encompasses  automated  highways  and 
computer-aided  vehicle  guidance. 

Rail  systems  and  trucking  agencies  are  us- 
ing GPS  as  the  basis  for  traffic  management 
and  scheduling. 


12  73  Amateur  Radio  Today  •  July.  1 994 


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m 


In  the  realm  oF  public  fiiireiy,  GPS  will  as- 
sist in  resource  managemeni,  allowing  dis- 
patchers to  accurately  determine  where  po- 
lice cars,  fire  trucks,  and  rescue  equipment 
arc  located  at  any  given  lime.  Police  dis- 
patchers will  know  the  exact  position  of  ev- 
ery car  available  or  in  use  and  can  send  a 
unit  to  assist  whenever  necessary,  possibly 
saving  an  ofUcer's  life.  Fire  departments  and 
rescue  squads  can  use  computer-based  maps 
and  information  giving  locations  of  fire  hy- 
drants, water  .supplies*  and  directions  of 
travel  Using  differential  GPS»  it  is  possible 
lo  locate  individual  rircfighters  inside  burn- 
ing structures. 

During  natural  disasters  such  as  earth- 
quakes or  floods  it  will  be  easy  lo  locate  un- 
derground utilily  lines,  boundary'  areas,  and 
limiis  of  ulTecied  areas. 


GPS  allows  land  survey  and  mapping  lo 
accuracies  of  two  inches  or  less.  Special 
techniques  and  equipment  are  used  for  accu- 
racies of  this  level 

The  locations  given  by  a  GPS  receiver 
can  be  applied  to  maps,  preventing  hikers 
from  becoming  lost.  Further,  in  the  event  of 
an  emergency,  hikers  can  transmit  (via 
phone  or  radio)  their  exact  locations. 

Important  GPS  Uses 

An  expedition  scaled  the  tallest  mountain 
in  Nonh  America.  Mt.  McKinlev,  in  June 
1989  to  determine  its  exact  height  by  use  of 
GPS.  The  exact  height  was  determined  to  be 
20306  feet,  which  is  14  feel  below  the  1954 
trigonometric  measurement  (anyone  for 
placing  a  repeater  up  there?).  Other  moun- 
tains measured  using  GPS  include: 


Ml  Fuji,  tallest  mountain  in  Japan,  at 
12,382  feet. 

Mt.  Logan,  Canada's  tallest  peak,  at 
19346  feet 

Mt.  Evenestt  tallest  in  the  world,  at  29,022 
ft. 

GPS  was  used  to  accurately  place  ihc  po* 
sition  of  the  Titanic,  During  the  Great  1993 
Flood  of  the  upper  Mississippi  River  Valley. 
GPS  was  used  extensively  to  monitor  areas 
covered  with  waten  Similar  advantage  of  the 
system  was  made  during  the  Christmas  Eu- 
ropean Floods  of  1993. 

GPS — ihc  Global  Positioning  System — is 
in  your  future,  B 

For  an  in-depth  study  of  GPS,  see  she  au- 
thor's latest  bo€7k.  Aviator's  Guide  to  GPS, 
published  by  TAB-McGraw  Hill:  telephone: 
(800)  23S  U28. 


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1 4  73  Ama  tear  Radio  Today  •  July,  1 994 


« 


Gtobaf  positioning  system  (GPS)  receivers 
display  latitude  and  longitude  on  ttieir  LCD  or 
CRT  screans.  They  also  show  SOG  (speed 
over  ground),  COG  (course  over  ground), 
speed,  and  distance  to  pre-memorized  event 
Of  waypoint  markers. 

The  latitude  and  lor^grtude  numbers  would 
lead  to  position  accuracies  of  approxin:iately 
10  feet,  bul  the  last  significant  number  regu- 
lariy  charges.  Why  the  change?  This  rs  be^ 
cause  your  positron  is  purposely  being  diluted 
by  ttie  Department  of  Defense  GPS  satelfite 
system  to  a  100- meter  radius  of  a  circle.  It*s 
called  "selective  a  variability/  and  purposely 
denies  pinpoint  accuracy  to  civilian  users  in 
order  to  provide  a  safeguard  to  national  de- 
fense. 

This  selective  availability— also  called  sig- 
nal dithering — can  be  all  but  eliminated  by 
subscnbing  to  commerdal  or  government  dif- 
ferential  GPS  signals.  The  differential  signafs 
correct  the  selective  avai! ability  error  factor 
from  somewhere  within  a  300-foot  circle 
down  to  within  a  5-foot  circfe  95  percent  of 
the  time*  For  the  ultimate  in  accuracy,  you 
would  subscribe  to  your  local  FM  slatron  sub- 
carrier  access  {SCA)  driferential  GPS  signals 
along  wttb  a  little  black  box  that  hooks  into  a 
differentia  I -ready  GPS  receiver. 

For  mariners,  the  differential  correction  sig- 
nals come  in  tree  of  charge  from  the  United 
States  Coast  Guard.  These  are  received  on 
the  300  kHz  marine  radio  beacon  band,  and  a 
DBR  that  simply  plugs  into  most  portable  or 
fixed  GPS  sets  tor  boating  position  accuracy 
of  approximately  1Q  feet.  The  U.S.  Coast 
Guard  differential  system  covers  all  of  the 
East  Coast,  all  of  the  GuFf  Coast,  and  stations 
are  going  in  right  now  for  thre  West  Coast  and 
Alaska ^  Canada  also  participates  in  the  differ- 
ential GPS  program  Hams  living  within  100 
miJes  of  a  participating  U.S.  Coast  Guard 
beacon  station  should  be  able  to  pufi  in  these 
low- frequency  signals,  modulated  MSK  (mini* 
mum  shftt  keying),  with  the  right  commercial 
equipment.  No  monthly  user  fee! 

But  latitude  and  longitude  coordinates  may 
not  mean  much  to  ham  radio  operators  using 
GPS  equipment  for  county -line  calculations, 
biking  topo  maps,  or  ihe  common  street  at- 
lases which  rarety  list  latitude  and  longitude. 
Hams  need  something  etse,  and  they  now 
have  it! 

One  expensive  solution  Is  to  tie  a  laptop 
computer  into  a  GPS  receiver  with  differentia] 
capabilities,  and  buy  mapping  software  or 
maps  on  CD-ROM,  If  you  have  a  computer, 
this  is  one  option  for  you  to  consider. 

!f  you  need  a  portable  mapping  device. 
Sony  is  just  coming  out  with  their  new  Pyxis 
Model  lPS-760  thai  uses  micro  C-Map  car- 
tridges, that  are  ordered  directly  from  the  sup- 
plier for  approximately  $129,  covering  several 
hundred  square  miles  of  area.  These  coukj 
be  cruising  charts,  topo  charts^  street  maps, 
or  even  the  popular  airplane  charts. 

Panasonic  and  Lowrance  Electronics  are 
also  ptannirg  on  hand-held  GPS  chart  de- 
vices which  will  give  you  the  cartographic  da- 
ta on  a  chart-like  screen  ttiat  covers  a  select- 
ed area  of  interest. 

Tnmble  Navigation  (Sunnyvale,  California: 
1/800/827-8000)  combines  the  power  of 


GPS  Maps  and  Charts 

by  Gordon  West  WB6N0A 

Thomas  Bros.  Maps  and  their  hand-held 
Scout  GPS,  which  converts  the  incoming  sig- 
nals to  grid  references  in  the  map  book.  Or, 
for  the  VHF/UHF  operator,  the  unit  can  actu- 
ally read  out  which  grid  square  you  are  in  with 
no  map  book  required! 

"Oirr  Scout  offers  a  choice  of  nine  coordi- 
nate displays:  latitude  and  fongityde  in  sec- 
onds or  minutes;  universal  transverse  Merca- 
tor  map  projection;  ordinance  survey  of  Great 
Britain;  Trimbte  Attas  from  Thomas  Bros. 
Maps;  Maidenhead  grid  iocator  system,  in- 
cluding sub-square  accuracy;  TrimWe  grid  lo- 
cator— extension  of  Maidenhead  for  addition- 
al accuracy." 

*With  any  of  these  readouts,  our  GPS 
equipment  is  ideal  for  the  ham  operator/' 
comments  Jim  Osdaie  K6EUD,  a  local  ham 
operator  who  teaches  GPS  navigation 
(714/779-5003). 

Many  ham  operators  have  discovered  a 
unique  fixed-mounl  LCD  screen  GPS  receiver 
from  Lowrance,  the  Global  Map  1000,  as  hav- 
ing the  most  buift-in  cartography  for  the  buck. 
Boat  GPS  sets  usually  incJude  an  oullfne  of 
the  United  Stales  as  part  of  the  basic  cartog- 
raphy built  into  ttie  unit-  For  a  close  took  at  a 
locaf  tiarbor.  you  would  purchase  $150  C- 
Map  or  Navionics  cartridges,  plug  them  into 
the  GPS  mapping  unit,  and  presto,  a  vague 
outline  of  the  U.S.  wiil  come  into  locaf  harbor 
detail,  C'Map  is  also  working  with  Navionrcs 
to  soon  supply  cartridges  for  selected  lakes 
and  rtvers  to  cover  those  hoi  fishing  spots. 

But  when  Lowrance  asked  tor  a  "canned" 
map  of  the  United  States  to  be  burned  into 
their  firmware,  little  did  they  know  what  was 
going  to  be  supplied — the  United  States  with 
all  major  freeways  and  expressways  built  into 
the  system  without  the  need  for  any  addition- 
al iocal  mahne  chart  cartridges. 

1  don't  go  anywhere  without  my  Lowrance 
GPS  set  in  a  rentaf  car"  comments  Bill  Alber 
WA6CAX,  a  traveling  marketing  consultant 


who  has  put  away  the  map  books  for  bis 
new  electronic  readout,  'When  I  am  talking 
to  someone  who  I  will  visit  in  a  few  weeks, 
I  teli  them  I  must  have  their  latitude  and  longi- 
tude along  with  their  office  address.  I  enter 
this  into  the  GPS  charting  device  ahead  of  my 
trip,  and  presto.  \  see  exactly  where  Tm  going 
as  I'm  pulling  out  of  the  parking  lot."  adds 
Alber.  "When  it  goes  beep  on  arrival.  I  am 
usually  within  100  feet  of  the  front  door," 
smiles  Afber. 

State  outlines  arrd  many  county  (ines  are 
also  included  in  the  canned  cartography. 
Same  thing  with  nvers,  too.  And  if  you  turn  on 
your  trail  plotler,  you  can  capture  exactly 
where  you  have  been,  and  see  exactly  the 
route  you  took.  To  demonstrate  the  accuracy 
of  the  plotter,  see  the  73  logo  in  Photo  B. 

All  marine-lype  GPS  sets  are  priced  at 
tfie  bottom  end  of  Ihe  long  list  of  equipment 
designed  for  commercial  surveyors.  A  survey 
set  might  run  $3,000,  bul  you  can  buy  a 
marine  Garmln  GPS  -50  for  under  $400!  The 
inexpensive  marine  sets  also  output  NMEA 
0183  data,  and  this  ties  into  those  S6O0  LCD 
chart  display  systems.  Those  marine  sets 
ateo  tie  in  nicely  with  APRS — automatic  pack- 
et reporting  system.  This  turns  your  GPS 
set  into  a  position  enunciator  that  squawks 
your  location  on  packet!  Not  only  can  you 
see  where  you  are,  but  other  APRS  systems 
can  actually  see  where  you're  going  on  their 
system. 

During  a  recent  trip  throughout  the  United 
States,  ]  found  that  the  GPS  antenna/receiver 
unit  worked  nicely  in  the  back  window  of 
rental  cars.  Only  now  and  then  did  the  recep- 
tion drop  out  when  I  was  in  between  tali  build- 
ings in  Miami  and  Los  Angeles. 

Manne  GPS  prices  wont  dip  much  beiow 
$400,  so  check  out  what  is  available  down  at 
the  marine  stores,  and  tune  into  1575  MHz 
and  get  set  for  hand-held  and  mobile  position 
finding. 


Photo  e.  The  trait  plotter  feature  aliows  you  to  display  exactly  wherB  you've  beer}— in  this  case,  on  the 
73  traiti 


73  Amateur  Radio  Todsy  -  Jufy,  1 994    15 


IHi 


Number  5  on  your 


kcard 


World's  Smallest  10  GHz 

ATV  Transmitter 


Build  one  on  a  PCB  using  only  a  few  componentsi 

by  Angel  Vilaseca  HB9SLV  and  Jean-Pierre  Morel  HB9RKR 


/ 


The  availabiliiy  of  cheap  surplus  GaAs- 
FETs  lately  has  made  a  lot  of  microwave 
experimenting  possible  for  amateurs.  This 
article  deiicribcs  a  new  kind  ol'  amateur  10 
GHz  low-power  transmiiicr  using  a  surplus 
GaAsFET,  mouitled  on  a  tiny  piece  of 
Teflon/glass  PCB.  Wideband  FM  modula- 
tion is  possible  for  ATV  operation. 

As  microwave-oriented  amaieurs,  we  (the 
author*^}  began  experimenting  back  in  the 
*80s,  using  Gunn  diodes  in  waveguide  as- 
semblies. These,  provided  ihey  were  home- 
by  ill,  using  cheap  surplus  diodes,  were  very 
cost-effcciive  when  compared  with  commer- 
cial transceivers  (e.g.  the  Gunnplexer).  'Hie 
main  disadvantage  wa.s  the  "plumbing-"  li 
took  a  lot  of  time  and  a  fairly  well-tooled 
workbench  to  build  vvaveeuide- based  de- 


Figare  I ,  A  GuAsFEJ osiillafor.  G,  D,  and S 

-  gate,  {tram,  and , source  respect tveh\ 


Figure  2.  In  a  ya^l  antenfta,  the  elements  are 
about  a  hulf-waveiength  long. 

16  73  Atnateur  Radio  Today  •  July,  1 994 


signs.  For  instance,  some  pans,  like  the 
screws  used  to  hold  the  diodes,  could  only 
be  made  w  ith  a  lathe. 

However,  if  you  were  ever  drawn  away 
from  ihc  10  GHz  band  bv  the  mechanical 
difficulties,  this  article  is  for  you.  The  10 
GHz  transmitter  we  are  describing  could 
hardly  be  simpler. 

The  GaAsFET  Oscillator 

Trying  to  design  a  GaAsFET  oscillator 
with  PUFF,  a  computer  program  previously 
described  in  this  masa/ine,  we  first  consid- 
ered  a  design  like  the  one  in  Figure  1 . 

Like  in  many  oscillators,  the  oscillation 
lakes  place  if  there  is  an  adequate  feedback 


from  an  amplifier's  output  to  its  input.  In  the 
oscillator  shown  in  Figure  I,  the  feedback  is 
provided  by  the  two  close-coupled  stubs 
connected  to  the  gate  and  drain  mi- 
crostriplines.  The  source  terminals  arc  con- 
nected to  the  ground  plane- 
Making  tfie  Oscillator  Radiate 

Any  conducting  patch  etched  on  a  PCB 
radiates  a  pan  of  the  energy  it  is  fed  with.  If 
the  dimensions  of  the  patch  are  small  in 
terms  of  wavelength,  little  energy^  is  radiated. 
As  the  patch  dimensions  increase,  radiation 
increases  too,  until  a  }J2  patch  dimension  is 

Cofuinued  on  page  IS 


Figure  3,  The  oscillator  circuit  dhnensions.  (See  text.) 


Feedback 


!n  ouf  oontinuing  effort  to  pre&ent  the  best  in  ama- 
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To  save  on  postage ^  why  not  fill  out  tlie  Product  Re- 
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1  Never  Say  Die 

2  Letters 

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5  Worlds  Smallest  10  GHz ATV Transmitter 

6  eMt/RFi  Defense  Strategies  fOf  Hams 

7  Review:  S  &  S  Engineering's  Frequency 
Counter  Ki! 

8  Review:  LDG  Electronics"  F01 

9  Delayed  Video  Trigger  for  Your 
Oscifloscope 

1 0  Muitiband  Halt-Wave  Delta  Loop  (MHDL) 

11  tcT^HOved  Resonant  Feediine  Dipofe 

12  RTTYLoop 

13  Man^ats 

14  Carr's  Comer 

1 5  Hams  with  Class 

16  QRP 

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29  Propagation 


ARE  YOU  BUILDING  A 


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73  Amateur  Radio  Today  •  July,  1 994     1 7 


World's  Smallest  10  GHZ 
ATV  Transmitter 

Continued  from  page  16 


COUPLED 
V  LINES 
A 


? 


COUPLED 
\  LINES 

/      B 


Figure  4.  For  PUFF,  !he  osiiUaior  is  an  am- 
plifier With  two  pairs  of  coupled  tines  con- 
nee  ted  end-to-end.  Various  A  ami  B  lengths 

were  fried,  wit  it  the  overall  !en0i  4  +  B  re* 
maining  X/2, 


feached.  Thh  is  when  radiaiiun  efficiency  is 
at  its  besit:. 

This  principle  is  not  new  to  us:  Yagi  an- 
tcfuia  ekmcnis  are  also  about  X/2  long  (Fig- 
ure 2)  and  they  are  particularly  efficient 
when  it  comes  !o  radiating  energy  from  our 
transmitters!  Radiation  from  microstrip  ele- 
ments is  used  in  so-called  miiTosTrip  anten- 
nas. 

What  we  tried  to  do  here  was  to  combine 
the  design  of  the  previously  mentioned  os- 
cillator with  n  microstrip  an  let  hill  Two  mi- 
crostrip antenna  patches  were  designed 
close-coupled  lo  each  other.  I'hc  GaAsFET 
input  (gate)  was  connected  to  one,  and  the 
output  (drain)  to  the  other,  thus  obtaining  ihe 
following  design  t Figure  3). 

We  decided  to  make  both  patches  w  ith  the 
same  dimensions  for  our  first  try.  In  fact, 
this  is  questionable,  because  if  the  two 
patches  radiate  widi  opposite  phases,  then 
their  respective  radiations  would  cancel  each 
other! 

Perhaps  a  more  in-depth  theoretical  (and 
mathematical)  approach  would  be  needed 
here. 

However,  experimentation  showed  that 
some  radiation  did  take  place.  In  fact,  some 
mutual  cancellation  from  the  i\vo  patches 
can  be  desirable  if  it  is  thought  of  as  equiva- 
lent to  Limiting  the  output  coupling  of  a  con- 
ventional oscillaton  Ff  all  possible  energy  is 
coupled  oul  of  an  oscillator,  its  stability  will 
be  bad,  because  its  characteristics  will  be  af- 
fected by  the  circuit  it  is  coupled  to. 

Designing  the  PCB 

Now,  there  are  four  dimensions.  A,  B,  C 
and  D  (FiE[ure  3 1  we  must  decide. 
We  described  the  circuit  to  PUFF  in  the 


Feedback 


Microwave 
Radiation 


Microwave 
*      Radiation 


video 
Input   ^ 

1 

pF 

33 

PF 

\ 

_         IK 

■ 

10K 


Gate   Supply 


6 
Drain  Supply 


All  parts  marked  wtth  an  asterisk  are  etched  on  the  pcb 
All   discrete  capacitors  and   resistors  are  SMDs. 

J =  Connected  To  Ground   Plane. 


SOURCE 


GAT 


DRAIN 


SOURCE 


I 


CHIIII 

33p   20 


V   VIDEO  GND 
INPUT 


+V 


Figure  5.  a)  Circuit  schematic,  h^  A  drilled  and  etched  donhle-sided  PC  hoard  for  this  pro- 
ject is  available  for  $5  plus  $130  S&fl  per  order  fi-om  FAR  Circuits,  18N64(}  Field  Conn, 
Dundee  (L  601  IS. 


18  73  Amateur  Radio  Today  *  July,  1994 


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CIRCLE  34  ON  READER  SEVICE  CAJ^D 


^m 


"IKEA'' 

parabo I i  c 
d  i  sh 


c 


osc 


((('h4 


50 


cm 


1       c 


reoB ; ver 
horn 
a  9  n  I  a  ! 


Figure  6.  The  tesf  setup. 


,13;  SB;  4?      31    JUL    1693 

ATTEN    ID   eta 


REF    »0  dem 

FEAK 

LDS 
10 


■  ■■  '  - 


ITA   SB 
SC   F3 


9,712    GHl 
-3«0S    dBm 


1 


CE^^'ER  S.710  bhz 

RES   B)4    3   3»#HZ 


VSW    i   IIHz 


SPAN    I .CSS    BHZ 


figure  7.  The  signal  at  the  receiver. 


follov^ing  way  {Figure  4): 

First,  the  coupled  lines  A  and  B  were  cho- 
sen with  ihe  same  low  impedance.  Low 
impedance  means  ihat  ihcy  are  broad,  like  a 
microstrip  anienna  paich*  Ditiiension 
B+D+B  should  be  equivalent  to  nbout  a  half 
wavelenaih  to  maximize  radiation. 

Second,  to  generate  enough  feedback  for 
oscillation  lo  occur,  rhey  were  chosen  with 
tight  coLtpling.  which  means  close  to  each 
other  Tliis  deiennines  dimension  D. 

Ttiird,  the  overall  electrical  length  of  bc3dl 
tines  put  end  to  end  (A)  was  chosen  at  about 
X/2  to  maximize  radiation.  The  point  at 
which  the  GaAsFET  was  attached  to  the  two 
patches  (dimension  C)  was  searched  with 
PUFF,  by  trial  and  error,  so  that  S,^  feed- 
back was  as  high  as  possible. 

Finally,  we  decided  to  start  experimenting 
with  the  PCB  pattern  shown  in  Fig- 
ure 5. 

As  an  aerial  we  used  an  aluminum 
parabolic  reflector  an  *iKEA'*  dish,  sold  as 
a  lamp,  available  cheaph  in  fumilurc  shops. 
fEdi!or*s  note:  The  authors'  QTH  is  Switzer- 
land, You  may  have  to  improvise  if  you  can- 
not find  the  fKEA  lamp  hKally-l  The  diame- 
ter of  this  lamp  dish  iis  40cm  and  its  focal 


length  is  rather  short,  at  about  1 1cm,  So  F/D 
is  low,  at  0.27,  The  oscillator  was  simply  put 
at  the  focal  point,  so  it  would  illuminate  the 
dish  ...  no  more  '"penny  feed."  1  low  is  this 
for  simplicity?  (Figure  6), 

Tlie  GaAsFET  we  used  was  a  "Red  Spot*' 
from  Birkelt,  25,  The  Strait.  Lincoln  LN2 
UR  UK, 

Dimensions  D  and  B  (Figure  3)  were  held 
constant  throughout  the  tests:  D  ^  0.5mm.  B 
=  10mm, 


For  our  first  test,  we  took  A  =  18mm  and 
C  -  6.5mm.  With  +V  supply  =  4  V  and  -V 
supply  ^  -3.5  V,  Id  was  23.4  niA  and  we  re- 
ceived a  -3  dBm  signal  with  our  hom  anten- 
na, 

Osciifaiion  frequency  was  lower  than  pre- 
dicted at  9.712  GHz  (Figure  7),  The  re- 
ceived signal  was  best  with  the  oscillator  be- 
ing shifted  away  from  the  focal  point,  at 
16,2cm  instead  of  1  Icm,  This  probably 
means  thai  the  radiation  angle  from  the  PCB 
Is  too  narrow  to  illuminate  the  whole  dish 
evenly  (Figure  8). 

Eventually,  the  GaAsFET  failed  (it  did 
draw  quite  a  lot  of  curreni)  and  was  replaced 


by  a  first-class,  expensive  Cl^'  1 8-23  from 
Siemens,  A  was  left  unchanged  at  1 8mm 

and  C  wa.s  tried  at  7mm.  The  received  signal 
was  much  lowen  at  -17.3  dBm,  With  C  ^ 
8,5,  the  oscillations  stopped. 

Most  interesting  was  the  fact  that  this 
small  change  in  C  brought  the  frequency  al- 
most 1  GHz  higher  at  HX653  GHz. 

We  replaced  the  CFY  18-23  with  a  new 
red-spot  GaAsFET,  with  C  left  at  7mm  and 
the  frequency  remained  the  same,  so  it  really 
seems  that  the  frequency  shift  comes  from 
the  C  modification,  rather  than  the  GaAs- 
FET change. 

To  lower  the  frequency  down  into  the  am- 
ateur band,  we  fitted  two  small  pieces  of 
copper  foil  to  the  ends  of  both  patches,  in* 
creasing  the  A  dimension  to  19mm.  This 
brought  the  frequency  to  10.293  GHz.  +V 
supply  was  Hr  3.5  V;  -V  supply  was  -4V;  Id  = 
16.5  mA. 

Figure  9  shows  the  received  signal  when 
ihe  oscillator  is  frequency-modulated  by 
sending  a  4.5  MHz  sinusoid  to  the  gate.  Lin- 
earity is  acceptable. 

Modifying  the  power  supply  voltage  did 
not  change  the  drain  current  much,  Frequen- 
cy did  change  but  not  linearly. 


Figure  S.  If  the  osciiiator  is  placed  fimtur  from  ihe  parabola  than  the 
focal  length,  it  iUwninates  tiie  dish  more  evenly. 


JMi  Am  =2      03   AUe    1992 
'^                                                                                            MKn-THK    10.3933    SM^ 

ner  ,0  ciatn          at  ten  ib  hb                                    -i7.s3  dSm 

10 

t 

— — ^1 

1 

■ 

i 

; 

MASK EH                                                A    f 
10.  £933    GHl                               l\  1 
-17.23    dBm                                 1  U 

\h 

% 

1 

r 

% 

WA   S3 

SC   FS 

r^^vMl 

fVHr«-i 

^^^^ 

V 

1 

vw 

DHft*,'^ 

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Mjy 

CORR 

. 

CENTS 

J 

R    10.293a    0-tZ                                                              SPAN    102.0   MHt 
RES   0W    1    MHZ                        VSH  BOS  HHZ                    &HP   2^3   wmac 

' 

Figure  9.  Output  sigrutl  when  the  oscillator  is  frequency  modulated. 


20  73  Amateur  Radio  Today  *  July,  1994 


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Figifri*  10.  A  preaffiplifier  connevi^d  to  a 
mkTostvip  atitenmL 


+V  Siippiv 
+3,0V 
+3.5V 
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-V  Supply  ID 
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4V  1 6,5  mA 

-4V  173  mA 


Frequency 

10.363  GHz 
10354  GHz 
10.376  GHz 


The  received  signal  wqs  best  ai  -17.23 
cBni  when  llie  PCB  way  ^ei  ai  13.5cm  from 


the  dish.  The  cross-polari/alion  attenualion 
was  rather  high*  w ith  a  maximum  of  30  dB. 

The  total  radiated  power  was  estimated  at 
about  1  mW:  Replacing  the  circuit  under  test 
with  a  Gunn  iransmiiicr  of  1  mW  known 
power  output  gave  the  same  signal  on  our 
lest  bench- 

We  tried  to  further  decrease  C  to  5mm. 
this  ^t\x  the  output  power  up  about  3  dB  and 
the  drain  current  down  to  i  1.4  mA.  Oscilla- 
tion frequency  went  down  to  10.180  GHz, 
which  11 11  owed  us  to  remove  the  two  pieces 
of  copper  foil  w^e  had  fitted  to  the  patt;hes' 
ends.  This  brought  the  fre^uenc)  back  up  lo 
10  430  GHz. 

We  then  discovered  thai  the  circuit  was 
radiating  both  on  10  GHz  and  5  GHz!  Wc 
had  not  noticed  this  al  first  because  the  shoii 
length  of  waveguide  between  the  hom  an- 
tenna and  the  receiver  was  acting  as  a  high- 
pass  filler;  (cutoff  frequency  of  f  X  1/2" 
waveguide  is  about  6.5  GHz).  Furlher  short- 
ening the  patches  cured  the  problem* 

Conclusion  ^nd  Furlher  D€ve]opment!; 

Well,  this  is  it:  We  have  made  a  seven- 
component  10  GH2  ATV  transmitter,  possi- 
bly a  Guinness  Book  record!  Stability  was 
good,  with  liiile  frequency  shifts  caused  by 
moving  objects  near  the  TX-  Although  we 
did  not  try  it,  temperature  stability  could 
probably  be  enhanced  by  enclosing  the 
iransmiuer  between  iwo  plates  of  expanded 


polystyrene.  This  material  has  very  small 
losses  al  U)  GHz.  Another  improvement 
could  be  fitting  a  dielectric  stabilizer  to  the 
oscillator. 

Simplicity  is  not  the  only  advantage  of 
building  a  transmitter  of  this  kind.  Having 
the  10  GHz  source  directly  al  the  para- 
bola's focus  also  avoids  losses  in  wave- 
guides, coaxial  lines,  transitions,  relays  and 
so  on. 

This  would  be  panicularly  inieresiing  in  a 
receiver.  The  preamplifier  could  be  built  di- 
rectly at  the  parabola's  focus,  the  dish  being 
illuminated  by  a  small  microsirip  antenna  at- 
tached next  to  ihc  pneamp  (Figure  10). 

As  we  know,  any  loss  between  the  anten- 
na and  the  prcamp  severely  affects  the  re- 
ceiver's noise  factor.  An  assembly  like  ihe 
one  shown  in  Figure  ilb  should  be  much 
less  lossy  than*  say.  the  one  in  Figure  I  ta, 
and  much  cheaper,  too,  when  you  consider 
the  price  of  an  SMA  connector  or  a  mi- 
crowave T/R  relay. 

One  last  word  of  caution:  As  for  all 
GlAsFETs,  it  is  highly  advisable  to  turn  on 
the  negative  gate  supply  slightly  before  the 
drain  supply,  because  this  keeps  the  drain 
current  at  a  safe  leveL  If  the  gate  is  left 
at  ground  voltage,  a  large  current  surge  at 
turn-on  could  blow  the  GaAsFET.  Mi- 
crowave semiconductor  chips  are  really  liny 
devices  so  their  power  safety  margin  is  quiie 
small. 


Figure  Ji.  af  A  man-  comemionat  iand  lossy)  sefup.  Note  the  I)  waveguide  losses,  2}  connecmr  losses,  J)  cmix  losses,  and  4>  relay  losses, 
b}  The  preamp  can  he  emiosed  in  its  shielding  box  Mith  a  small  microsmp  element  ^lued  on  the  outside.  The  assembly  is  placed  in  from  of 
the  pamhola  with  the  mkrostrip  patch  at  the  focus. 


22  73  Amateur  Radio  Today  •  July,  1 994 


JZ. 


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EMI/RFI  Defense 

Strategies  for  Hams 

Keep  those  troublemaking  signals  out  of  your  mobile  installation! 


by  Donald  Koehler  N7IVIGT 


You  just  finished  the  installation  of  a 
brand-new  VHF  (or  UHF)  FM  rig  in  ihe 
car.  You  mm  it  on  and  gei  a  good  VSVVR 
and  signal  check.  After  cleaning  up,  your 
significant  other  asks  for  a  ride  to  the  mall 
on  I  he  other  side  of  lown.  You  start  the  car 
and  fire  up  the  rig.  Squuilch  needs  adjusting? 
You  crank  it  up  and  drive  off.  Repeater  traf- 
fic light?  Friends  complain  you  don't  answer 
calls?  You  may  be  the  victim  of  RFl/EMI. 

What  is  RFI/EMl?  Radio  Frequency  In- 
terference, also  known  as  Electromagnetic 
Incompatihility,  h  when  one  (or  more)  elec- 
tronic or  ciectfica!  device  affects  or  di>njpts 
the  normal  operation  of  a  "victim*^  system* 
In  the  example  above,  the  new  radio  was 
victimized  by  weak,  wideband  noise  from 
digital  automobile  systems.  This  problem  is 
often  exhibited  by  "loiit"  calls  or  high 
squelch  settings. 

This  article  will  cover  EMI/RFI  defense 
strategies,  installation  practices,  and  hazards 
which  may  result  from  using  certain 
EMJ/RFl  ctjres.  Let's  start  by  examinitig 
three  broad  areas  of  action  which  can  help 
resolve  EML 

In  tlie  broadesi  sense,  EMI  can  be  com- 
bated by  avoidance,  aftenitation  and/or  iso- 
lation. Any  of  these,  or  some  combination  of 
the  three,  may  be  necessary^  to  eliminate 
EMI  problems  with  insiahed  equipment. 

Avoidance 

The  least  expensive  of  these  strategies 
may  well  be  avoidance.  Avoidance  covers 
several  areas: 

•Pre-iristallaiion  checks  of  the  area. 

•Use  of  commercial  software  to  fmd  har- 
monic "hits." 

•Use  of  service  bulletins. 

♦Power  levels  appropriate  for  intended 
communications. 

Each  one  of  tliese  options  offers  some  ad- 
vantage for  the  ham  or  other  installer.  While 
not  listed  in  any  particular  order  of  impor- 
tance, these  areas  should  be  the  first  you 
turn  to  in  installation  planning  and  practice. 

The  use  of  a  broadband,  high-speed  scan- 
ner can  go  a  long  way  toward  identifying 
potential  EMI  sources  after  a  problem  arises. 
Use  of  the  scanner  prior  to  an  installation 

24   73  Amateur  Radio  Today  •  July,  1 994 


can  save  time,  money  and  possibly  missed 
emergency  traffic.  How  do  you  use  the  scan- 
ner in  a  pre-insialiaiion  check? 

I  suggest  using  scanners  in  two  ways. 
First,  load  all  of  the  common  channel  fre- 
quencies you  intend  to  use  into  the  scanner. 
Then,  with  the  vehicle  operating  normally 
(assuming  a  mobile  installation),  let  the 
scanner  run.  Listen  for  **hits"  or  EMI  on 
these  loaded  channels.  The  hit  n\ay  sound 
like  static,  a  whistle  or  a  rough  bu/z.  Open 
the  hood,  then  caiefuily  work  the  antenna 
near  the  baiiery  and  any  of  the  installed 
"black  boxes"  (fuel  injection  computers, 
etc).  Do  the  same  on  the  inside  of  the  vehi- 
cle. Run  the  heater  or  other  accessories  at 
this  time* 

If  no  noise  source  appears,  switch  the 
scanner  to  the  search  mode  and  set  the 
search  limits  to  just  above  and  bellow  the 
range  of  frequencies  desired  for  use  in  the 
installed  equipment.  Most  modern  scanners, 
such  as  the  ICOM  miniature  series  and  AOR 
handhelds,  cover  1  ()t)  kHz  to  2.0  GHz.  They 
are  more  than  useful  for  ^his  check.  Note  the 
frequencies  where  the  hits  occur  and  see  if 
they  are  on,  or  are  harmonically  related  to. 


planned  frequencies.  More  on  this  in  the  "In- 
stallation Practices**  section. 

The  use  of  commercial  software  to  run 
checks  on  installed  or  contemplated  frequen- 
cies  may  save  a  lot  of  grief  up  front.  Har- 
monic relationships  may  he  hard  to  discern, 
but  the  pruhlenis  which  crop  up  are  real  in- 
deed. Most  commercial  software  is  powerful 
enough  to  keep  you  out  of  trouble.  Take  a 
minute  to  run  these  checks  before  instaUing 
new  equipment  into  systems  or  vehicles 
where  communications  equipnicni  is  already 
in  use. 

If  you  can  take  a  few  moments  to  look 
through  equipment  service  bulletins  prior  lo 
installation,,  you  may  save  time.  Look  for 
w^arnings  on  minimum  equipment  clear- 
ances, grounding  and  power  rcquiremenls, 
antenna  or  power  cabling  restrictions  and 
other  information  which  may  impact  on  the 
planned  installation.  Finally,  use  the  least 
amount  of  power  necessar>'  For  the  job.  Mod- 
em radio  sets  have  compulcr-conlrolled-and 
-set  wideband  frequency  and  power  settings. 
Never  use  more  power  than  is  called  for  in 
the  instalktion  package.  Besides  being  bad 
practice,  it  can  cause  EMI  or  desense  in 


Photo  A.  Don'i  leave  power  wire.\  nwuifig  imsecured  across  the  engine  compartment!  Poor 
installation  practices  often  lead  to  EMI/RFI  problems. 


1M 


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Bu^^pth  confidence] 


It's  easy  to  order  from  CEI.  Mail  orders  lO:  Communic* 
tions  Electronics  Inc.,  Emergency  OperaUons  Center,  P.O.  Box 
J 045,  Ann  Arbor,  Michigan  48106  U.S.A.  Add  Jl 5-00  per 
radli>  for  U.P.S.  ground  shipping  and  handling  in  the  conti- 
nental USA  unkss  oihenvise  stated.  Add  $8.00  shipping  for 
all  accessories  and  pnblkations.  Add  $8.00  shipping  per 
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For  credit  card  orders  call 

ISOaUSA-SCAN 

Communications  Electronics  Inc. 
Emergency  Operations  Center 

P.O    Box  1045.  Ann  Arbor.  Michisan  4810^1045  USA. 
For  btformatlon  caU  5 1 5  996-gS«8  or  FAX  5 13^^'SS8S 


I 


Fhoia  Br  Using  a  scanner  wili  help  pinpoint  problem  ^* black  boxes." 


orher  installed  equIpmenL  In  this  case,  the 
old  saying  *1f  a  little  is  good,  gobs  is  great*' 
doesn't  hold  true. 

AtlenualioD 

The  issue  of  power  output  brings  us  lo  ibe 
nexi  of  ihe  major  strategies,  attenuiiiion. 
When  EMI  problems  arise,  one  of  the  main 


effons  taken  by  experienced  technicians  is 
to  attenuate  the  inierfering  signal  This  at- 
tenuation may  taki^  numy  forms.  The  nn>sl 
typical  is  using  filters,  both  RP  and  IF.  You 
may  not  nonnally  consider  cavity  fihers, 
cfysiaJ  fihc^^  and  alternate  siting  of  antennas 
to  be  a  form  of  aitenuaiion — but  that's  what 
(hey  do  to  the  unwanted  signal.  One  filter 


strategy  often  overlooked  is  using  ferrite 
beads  on  power  leads  and,  occasionally,  on 
RF  cables.  Finally,  bypass  capacitors  on 
power  leads  or  power  sources  offer  a  low 
impedance  path  to  ground  for  EMI  signals. 

Isolation 

The  third  sifaieev  is  isolation,  Bv  the  use 
of  shielding,  bonding,  and  AC  or  DC  filter- 
ing, the  communication  equipment  can  be 
isolated  from  EMI  signals.  The  shielding 
may  take  the  form  of  conductive  foils,  tubes 
made  of  conductive  or  attenuating  material, 
conductive  caulks  and  conductive  tapes. 
When  ysing  these  conductive  shields,  ex- 
treme care  must  be  taken  to  ensure  the  mate- 
rial will  not  come  loose  and  short  out  other 
equipment.  The  idea  of  the  shielding  is  to 
conduct  the  EMI  signal  away  from  your 
equipment  and  to  provide  a  low  impedance 
path  to  ground.  Another  way  to  do  this  is  to 
ensure  that  all  equipment  is  properly  bonded 
to  grt)und.  New  vehicles  make  extensive  use 
of  plastics  and  exposed  metal  that  often  have 
been  coated  with  anti-rust  compounds. 

Bonding  can  take  several  different  forms. 
Use  of  conductive  strapping,  lyinL»  together 
both  radio  equipment  and  mounts  to  the  ve- 
hicle frame,  i^  a  good,  low-cost  start.  Further 
work  lo  tie  the  vehicle  body^  frame  and  neg- 
ative battery  terminals  into  one  circuit  may 
yield  results  to  reduce  background  noise, 
When  running  power  leads,  make  the  run  as 


A  NO-RADIAL  VERTICAL 
THAT  COVERS  80  OR  75  METERS? 

THERE'S  ONE  NOW! 

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the  so-called  halfwaves.  Ask  for  our  free  brochure  for  complete  specs 
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Model  HF9V"X  (shown  to  the  left)  for  80/75,  W,  30,  20, 
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Model  CPX  counterpofse  kit  for  Butternut  models 
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base  of  antenna.  Mast  not  provided. 

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P.O.  Box  1234,  OlmitO.  TX  78575  (210)  350-5711 


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26  73  Amateur  Radio  Today  •  July,  1 994 


Explore  The  World  of  Quorum  Wefax 


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2  7  day  programmable  schedulers 

Automatic  dtf^italgain  lock  in 
ALI^  modes,  I'LL  clocking 


QFAX  Features 

I  GOES  /  Meteosat  Wefax  Reception 

I  NOAA  /  Meteor  APT  Reception 

I  HF  Nafax  Reception 

I  Dual  RF  ports  for  geosync  and  polar 
reception  under  software  control 

integrated  preatnp  and  down  con- 
verter power  inserters 

SO  user  definable  configurations 

Software  controlled  receiver  with  2 
UHFf  10  VHF  memories  and  scan 

On  board  audio  amplifier  and 
speaker  with  software  controlled  vol- 
umcj  squelch  and  mute 

Autotnatic  Unattended  Animation 
works  continuously 

8  bit  data  for  up  to  256  gray  levels 

View  at  up  to  1280  x  1024  256  color 

Use  TIFF,  GIF  or  PCX  fde  formats 
and  convert  to  BMP,  JPEG,  EPS 

and  binary 

Contrast,  Brightness^  3D  effect. 
Sharpen^  Smooth^  Noise,  MistO'^ 
grams  and  other  image  processing 


Ephemeris  based  NOAA  APT  navi- 
gation With  geo-political  and  Lat- 
Lon  overlays 

NOAA  Tools  show  satellite  path, 
Lat-Lon  of  cursor,  distance  and 
bearing  to  reference  point 

Automatic  Temperature  Calibration 

Color  Palettes  and  NOAA  curves 


Quorum  Communications,  Inc.  fa\(214)  915-o27(» 

8304  Esters  Blvd.  -  Suite  850  -  Irvin",  Texas  75063  (214)  915-0256  BBS  (214)  •>15-0346 


' 


I 


CIRCLE  257  ON  READEFl  SERVICE  CARD 


Fhoio  C.  Using  a  svanucr  to  di'tevmine  ihe  best  mure  for  power  leads  saves  time  ami  trouble. 


short  as  possible  using  proper  gauge  wire. 
AC  and  E>C  fUters  such  as  chokes  and  ca- 
pacitors will  help  lo  keep  "hash"  or  wide* 
band  noise  out  of  equipment.  I  have  had 
luck  with  additional  filtering  gaitied  from 
ferrite  beads  placed  over  the  power  leads* 
Secure  these  ferrite  beads  with  glue  or  tie- 
wraps  to  avoid  dan^tage  to  the  bead  caused 
by  movement.  Now  let's  lie  this  information 
into  the  Installation  process* 

Installation  Practices 

When  first  planning  the  installation  of 
communicaiions  equipment  in  a  vehicle, 
take  a  moment  to  "sweep*'  the  area  with  a 
scanner.  This  should  show  potential  EMI 
sources,  T\  pical  areas  are  near  vehicle  black 
boxes,  digital  dashes  and  other  displays  with 
multiplex  drivers.  Once  any  EMI  sources  are 
identified,  route  power  and  RF  cables  away 
from  the  source.  If  the  cable  royting  doesn't 
allow  for  avoidance,  the  use  of  shielding 
may  be  required, 

Fie.vible,  conductive  tapes,  conductive 
caulks  or  foils  can  be  uh^cd  lo  cover  the 
cabling  which  runs  by  the  source.  Short 
lengths  of  cable  requiring  this  EMI  cover 
caji  he  easily  fabricated  in  the  Held.  Ground- 
ing of  this  cover  material  is  usuany  not 
necessary.  Each  application  will  be  unique, 
though.  Common-sense  precautions  are 
essential  when  using  conductive  materi- 
als around  power  sources.  Covering  conduc- 
tive materials  with  insulating  taj>e  will  not 


impair  the  shielding  properties  of  the  ma- 
terial 

Taking  the  time  to  bond  the  radio,  the 
mount  and  the  vehicle  body  together  can 
eliminate  sources  of  wideband  noise.  When 
installing  mobile  computing  equipment,  this 
step  may  become  even  more  important  as 
this  equipment  can  often  generate  large 
amounts  of  wideband  digital  noise.  Use  care 
to  bond  the  interconnecting  cables  and  con- 
nectors. Ensure  solid  ground  paths  on  the 
vehicle  by  sanding  the  area  around  the  con- 
necting fastener.  The  use  of  modern  anti- 
rust  compounds  can  impair  or  raise  the 
impedance  of  the  ground  path.  To  protect 
the  ground  connection  and  fastener,  the  use 
of  conductive  caulks  or  grease  is  recom- 
mended- Use  of  small  an-sounis  of  conduc- 
tive caulks  under  mount  ''fingers"  may  im- 
prove grounding  of  blind  mount  antennas 


when  insMling  equipment  in  off-road  vehi- 
cles or  in  humid  climates. 

As  always^  when  installing  equipment  in 
off-road  vehicles,  lake  the  lime  lo  read 
both  equipment  and  vehicle  technical  data. 
I  have  had  good  luck  with  these  rule-of- 
ihumb  procedures  when  installing  radio 
equipment  in  vehicles  as  diverse  as  air- 
craft t^ueling  trucks,  snowplows,  fork- 
lifts  and  fire  trucks.  If  you  have  quesiiuns, 
talk  to  your  vehicle  service  personnel  or 
dealer. 

Avoiding  Hazards 

Even  the  besi-planned  installation  can 

generate  hazardous  conditions.  Let's  look  ai 
some  of  those  conditions* 

When  using  conductive  materials  for  at- 
tenuation or  shielding,  be  carefuH  These 
materials  may  become  conductors  of  oppor- 
tunity or  pan  of  sneak  circuits  not  protected 
by  fuses.  To  guard  against  this  hazard,  1 
fuse  both  positive  and  negative  power  leads 
as  close  to  the  battery  as  possible.  Foils 
used  for  shielding  can  cause  heat  buildup. 
Before  using  foil  as  shielding  material,  en- 
sure thai  doing  so  will  not  violate  the  vehi- 
cle's warrantv.  After  installation,  check  all 
vehicle  systems  with  the  installed  equip- 
ment up  and  transmitting.  Imagine  how  em- 
barrassing (and  dangerous)  it  could  be  if 
your  transmitter  caused  the  vehicle  anti- 
locking  brake  or  fuel  injection  system  to 
fail,  X^Tule  these  types  of  problems  are  rare, 
it  on!y  takes  a  moment  to  check  EMI  inter- 
actions with  the  vehicle's  systems  after  the 
msiallaiion  is  complete. 

After  alL  if  you  didn't  install  the  vehicle 
alarm,  cellular  phone  or  stereo  equipment, 
you  must  be  sure  that  these  common  sys- 
tems don't  cause  problems  for  your  new 
mobile  rig.  Take  the  time  to  use  some  of 
these  strategies,  and  enjoy  your  EMI -free 
mobile  operations* 


Installation  Hints 

Good  installation  practices  vM  go  a  long  way  toward  preventing  possible  EMI  problems. 
Try  these  tricks — they  work  well  for  commercial  and  amateur  Installations: 

■Replace  the  battery  terminal  clamp  with  a  new,  tight-filting  clamp.  Use  the  kind  with  a 
new  ^'generator'  lead  cast  into  the  damp.  Pull  the  DC  buss  line  power  from  this  clamp. 

'Use  a  multiconnect  or  ijarrier'^  block  for  your  DC  buss.  This  makes  it  easier  to  place  by- 
pass capacitofs,  if  necessary. 

•Don't  splice  wires^  il  at  all  possible.  Each  joint  is  a  possible  corrosion  spot  that  could 
cause  problems, 

•Don't  install  the  radio  next  to  or  under  heater  vents  or,  on  older  cars,  near  the  heater  or 
wiper  motors. 


QUICK.  EASY,  &  COMPACT 

Ffash  cards  'NOVICE  Ihru  EXTRA"  theorv  Kev  words 
undafljned  Over  4000  sets  m  use!  For  beginrkor.  OMs, 


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' 


rr 


Ortier  Today i 


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OCN0t*L 

^mZ     T^»  VIS  STU  DY  CARDS 

jwinew      u.m  P.O.  BOX  17377 

CLiiB  DI5CDUHT9   HAITI ES BURG,  MS  3S404 


\ 


CIRCLE  1W  ON  READER  SERVICE  CARD 


mpaiief  c»n  Ihc  *if  'roufMl  ihc  clock  w  powers  your  ini>*  HF  stotioii  \ 
60  hr»  M  muftlh.  Corrtml  trircUll  £)K«d»  eha/gt,  pfOtetlA  pd  celli  & 

(dOt)373-$425  n^^^  ^^^^  ^^^^  ut^4605 

CIRCLE  33€  on  READER  SERVICE  CARD 


PAY  TV  AND  SATELLITE  DESCRAM8UNG  1994 
NEW,.., free  BBS  with  sub  lo  An^rican  Hacker. ..New  Titles 


Pof  TV  afrd  S^eiiiti  D«cr.anb4trtg  1^^  —zi'-^i  'ai«i\  <:^X^  bOs  and  IBldlfr 

btv  Sc^iE-T^cj.  '.y-'-j-.i  DypatiHv  &m  Mes  lulilL  f£M%.  ?';  O-jr  btH  |d. 

S7W  ^n^iujes  fisSi   HKkv  VMh  AI  t^i  lixwi  SlS  9£  CKh  3&4  »  or 
S-ES2M  Amcflcin  Hadur  mom^  nc*  ^c^^dgA  cabis,  satefist  conitK^er^. 

Tifit  Eurepean Senm^ing SystMni. 480 pages. OS'S®  naw oB^oq |1 


SCRAMBLING  MEIflfS 

1S52  H^rtel  Ave..  M153,  Buffalo,  NY  1421fi 
VoJCQ^ AX/BOS- 7 1«.Q74.?i»Q  COO-  s  ara  OK.  Add  S6 


CIRCLE  3e  ON  READER  SERVICE  CARD 


28  73  Amateur  Radio  Today  •  July,  1 994 


m  I BIJLLETIN  i 


July.  1994 

182  North  Maple 
P.O.  Box  73 

Watertown,  SD  57201 

The  wkai  you  say  is  w^t  you  g£i  ^taU' 


INC 


AMATEUR  CENTER 


oM^t  ^teat 


HOURS:  MON.  -  FRI.  9-5  p.m.^ 

SAT.   B-1  p,m. 
CLOSED  SUNDAYS/HOLIDAYS 


^ 


V/M 


Write  for  our 
current  bulletin 

and  used 
equipment  list. 


SELECTION 


Hoppy  4th  of  July  I 
from  AH  the  Gong  | 

Stan 

WOiT 

J{fn 

We0MJY 

Darrell 

WO0GDF 

Jaacm 

KBOiUS 

Marty 

Tim 

KBOIOW 
WDOFKC 

David 

KA0JDN 

Slovo 
Lori« 
Sharon 

Shipping 
Bookkeoprng 

Receptionist 

Lto  R:  Jim  SiTiith,  President, 
with  Stan  Burghardt^  founder. 


J    I     I   1    «>    !■  I  ♦  »—  -4  H    ■«  - 


aM) 


TdaaJ    -    ll    ■  J    kit   *    1 


S%0 


■  i|   ^-rA   *   l-|>#-va   k    ..  J    .    1-^1 


I .  I  _-  ■'^■*i-T-rL*_-^_^J*A'' . '  .* .  a^  i '  I  * :  L  t  _"i  •■_*  -^ 


_l,|.*jiyy,ri»i(!!_ 


■     -     "    •         _'.«.•  S.t-  -t    I     -  -    ^  -   -  J    i.  -     . 


upott; 


able  to  place  one  s  complete  confidence  in  for  all  your  ham 
m^o  |j.eed§,  esp.  rejgting  to  Burghardt  Araateur  Q§ntej. 


■,!-■-'.'-•  '..*.^- i^--- 


■-v.^^^ ,'.'  '.'i  Vi  .-I'.vr' 


.  ^  1 1  till 


- 1  ■  - 1 1-  J 


.    J     -'I    I     6-|?B  4   J     -    I    I.   J     p.  . 


CALL  US  TODAY! 


reliable  staff  —  most  of 

our  staff  has  been  here  at  least 
15  years*  Stan's  been  here  for 
57  years. 

reliable  service  —  fully 

authorized  Iconi,  Yaesu  and 
Kenwood  service  center. 


! 
I 
I 
I 
I 


1 


Sales  Order  Line 
800-927-HAM  1  (4261 

For  Teehnical  &  Info. 

(605)  886-7314 
FAX  (605)886-3444 

FAX  PRODUCT  INFO 

(605)  886-6914 

CLIP  &  SAVE  • 


) 


T 
I 
I 
I 
I 


Call  US  TODAY! 


reliable  equipment  — 

we  have  all  the  brands  you 
want, 

reliable  used  gear  — 

fully  reconditioned  and  guar- 
anteed. We  take  trades.  If  we 
don*t  have  what  you  want,  get 
on  our  want  list. 


73  Review 


Number  7  on  yiMir  Feedback  card 


by  Michael  Bryce  WB8VGE 


Engineering's 


S  4  S  Engineering 

14102  Brown  Rd 

SmithsburgMD  21783 

Telephone:  (301)  416-0661; 

Fax:(301)416-0963 

Price  Class:  Kit— S49.9S: 

As^fnbled  and  tested— S69.95; 

4Kifgit  add-on  kit— $16.95. 


Frequency  Counter  Kit 

Now  you  can  count  frequencies  'til  your  heart's  content. 


When  S  3i  S  Engineering  sent  me  this  fre- 
quency counter  kit  for  review,  gosh,  did 
li  bring  back  memories.  My  first  home-brew 
frequency  counter  came  to  fife  In  the  mid- 
70s.  Ofi,  those  were  the  days!  Johnny  Car- 
son was  king  of  fate-night  TV,  the  Bay  City 
Rollers  were  rocking  Top  40  radio,  and  the 
USSR  and  the  USA  were  sneering  at  each 
other.  All  you  needed  for  a  frequency  counter 
back  then  was  a  VW  bus  full  of  TTL  logic 
chips,  15  pounds  of  solder,  yards  of  multicol- 
ored wire  and  several  PC  boards  to  hold  ev- 
erything together  Any  ol'  5  volt  supply  at  27 
amps  was  all  it  took  to  fire  her  up.  On  a  good 
day,  with  the  wind  blowing  just  rights  you 
might  be  able  to  read  10  MHz.  Provided  you 
handpicked  the  first  gate  chip,  a  74HS90, 

The  S  &  S  Engineering  Counter  Kit 

We've  come  a  long  way  since  my  first 
home-brew  frequency  counter.  S  &  S  Engi- 
neering now  has  available  a  frequency 
counter  kit  for  under  $50  bucks.  Even  on  its 
worst  day.  Its  top  end  \s  75  MHz,  Why,  with 
the  exception  of  two  wires  for  ttie  battery,  ev- 
eryltiing  Is  on  one  PC  board.  Best  of  all.  the 
entire  counter  can  be  run  by  a  single  9  vo!l 
battery. 

The  display  is  a  large  1"  LCD  giving  you 
four-digit  resolution.  This  can  be  expanded  to 
eight  digits  later  if  you  wish.  The  upgrade  is 
simple,  easy  and,  most  of  all»  cheap— less 
than  $20. 1  highly  recommend  you  get  the  up- 
grade to  eight  digits. 

The  S  &  S  Engineering  counter  kit  consists 
of  a  high  quality  double-sided  PC  board  with 
plated-through  holes.  The  PC  board  has  the 
parts  layout  sifk-screened  on  It,  and  i£  has 
been  laid  out  so  the  top  third  of  the  boand,  tfie 
portion  holding  the  LCDs,  can  b©  cut  from  the 
logic  section.  This  way.  you  can  mount  the 
display  away  from  the  logic  section  for  a  cus- 
tom Installation.  There  are  only  12  wires 
needed  between  the  display  and  logic.  Rit> 
bon  cable  would  be  idea!  for  this.  I  did  not 
separate  the  two  for  this  review. 

TTie  kit  does  not  come  with  a  cabinet;  that 
part  is  left  up  to  the  builder.  There  are  four 
metal  standoffs  supplied  to  raise  the  PC 
board  up.  This  way,  you  can  leave  it  as  is  and 
just  use  the  bare  circuit  without  a  box. 

30  73  Amateur  Radh  Today  •  July,  1 994 


As  with  all  of  the  S  &  S  Engineering  kits, 
the  part  quality  is  first-rate.  No  "hamfest  spe- 
cial" parts  or  surplus  goodies  are  in  this  kit. 
As  complex  as  a  frequency  counter  is,  most 
of  the  work  is  done  by  specialized  chips.  This 
reduces  the  overall  part  count  of  the  kxt  to  just 
a  handful  of  IC  chips.  All  the  tCs  come  in 
static-protective  packaging.  The  kit  includes 
everything  you  need,  including  a  9  volt  bat- 
tery snap.  Sorry,  the  battery  is  not  included. 

Assembly 

Assembly  is  very  straightfonvard:  Vou  start 
with  the  resistors,  move  on  to  the  capacitors, 


and  finish  up  with  the  transistors.  The  IGs  are 
installed  next.  Although  IC  sockets  are  not 
provided  with  the  kit,  you  should  use  them. 
The  IC  sockets  are  cheap  insurance  in  case 
you  solder  a  chip  in  backwards  or  install  the 
wrong  chip  in  the  right  hole.  Unsoldering  an 
IC  from  a  doubte*sided  PC  boafd  with  plated- 
through  holes  is  not  for  the  weak-at-heart. 
The  kit  requires  six  14'pin  sockets  and  one 
16-pin  socket.  There  is  one  40-pin  chip  under 
the  LCD  display  that  you  can't  use  a  socket 
on.  It  would  make  the  chip  too  tall,  and  make 
it  impossible  to  mount  the  LCDs  on  the 
board. 


A  NEW  COIMCEPT 

IN  HF  TRANSCEIVER  DESIGN 

FROM  A  NEW  COMPANY 


»  poieio    IRJ 


RANSoervBR 


ri^  «I7^ 


«*  »■=  «* 


^f^ 


pBicomm 


im 


.09 


Patent 
Pending 


Patcomm  Corporation'^ 
introduces  the  PC- 1610"  a  ful!  featured  HF  trans- 
ceiver with  built-in  keyboard  interface.  Plug  a  stan- 
dard IBM  XT*  compatible  keyboard  Into  a  PC-1610 
and  instantly  enjoy  keyboard  CW,  RTr/  (BAUDOT 
and  ASCII)  data  communications.  Incoming  morse 
&  RTTY  data  is  decoded  and  displayed  on  the  built- 
in  LCD  display.  The  PC-1610  offers  the  following 
features: 

■  Built-in  XT  keyboard  interface  (keyboard 
optional) 

■  160-10M  ham  band  coverage 

■  USB/LSB/CW/FSK  modes 

■  75W  output  power 

■  Built  in  digital  power/SWR  meter 

■  DDS  VFO  with  1  Hz  step  size 

■  Selectable  variable  speed/fixed  1  GHz  step 
VFO  tuning 

■  Built-in  24hr  dock 

■  90  tunable  memories 

■  1  scratchpad  memory 

■  9  (256  character)  keyboard  data  buffers 

■  Built-in  5-75  wpm  IAMBIC  keyer 

■  Built-in  2.4KHZ,  1 ,8KHz,  500Hz.  200  Hz  & 
RTTY  filters 

■  Notch  filter 

■  Select  1  of  3  antennas  from  front  panel 

SpecrtiGatlons  are  subject  to  change  without  notice, 
'  fBM  XT  is  a  registered  trademark  of  the  IBM  Corporation* 


Basic  display  lets  you  know 
exactly  where  you  are. 


n035lO-T 
n035fO-R 


GS30 


i  IL.tL.iLj 


Standard  Display 
shows  RX/TX  VFO 
freq's,  time  and 
current  memory 


Send  &  Receive  in: 

CW  /  RTTY{BAUDOT)  /  ASCII 


Incoming  data 

Outgoing  data 
appears  here 


Store  up  to  nine  256 
character  messages. 


N.035lO'T 


LJ 


3>  cnnnED    nsQ 


Messages  can  be: 
edited,  sent  & 
appended  to  out- 
going message 

Format  &  Edit 

stored  MSG's  here 


PC-1610    = 


HF  XCVR 


The  PC-1 61 0  Performs  the 
functions  of  an  HF  Trans- 
ceiver, Computer,  Data 
Controller  and  Control 
Software  all  in  one  package. 


DATA  CNTLR 


The  PC-IBIO  has  too  many  features  to  adequately  describe  in  one  ad. 
call  or  write  for  a  detailed  brochure— Major  Credit  Cards  Accepted. 

Designed  and  manufactured  in  the  U.S.A. 
Phone:  (51 6J  862-6512  ■  Fax:  (516)  862-6529 
7  Flowerfield  Ml  00,  St.  James  NY  11780 

CIRCLE  321  ON  READER  SERVICE  CAM) 


As  with  most  counters,  you  can  select 
the  gate  time  of  the  counter.  You  can  select 
between  10k,  Ik,  100,  10,  or  1  Hertz  reso- 
lution. A  multi-poie  rotary  switch  mounted 
directly  on  the  PC  board  selects  the  gate 
time.  There  are  no  interconnecting  wires 
to  worry  atxjut.  But,  this  switch  might  prove 
a  pain  in  the  butt  if  you  want  to  mount 
the  logic  board  separate  from  the  display^ 
Some  forward-thinking  would  be  in  order 
before  applying  soider  to  the  switch  termi- 
nals. 

Assembly  went  along  without  a  hint  of 
trouble.  The  instructions  are  a  bit  thin,  but 
they  get  the  ]ob  done.  All  in  all,  ft  took  me 
about  two  hours  of  work  to  complete  the  kit, 
even  with  extra-long  breaks  for  Oreo  cook- 
ies and  Diet  Coke.  I  installed  the  extra  LCD 
and  Its  driver  chip,  too. 

Testing  the  counter  ts  about  as  simple 
as  you  can  get.  Apply  power,  and  connect 
the  input  of  the  counter  to  a  test  point  on  the 
PC  board.  If  everything  went  in  as  it  should, 
you'll  see  10  MHz  on  the  display.  A  trimmer 
capacitor  on  the  PC  board  calibrates  the 
counter  to  either  WWV  or  a  known  10  MHz 
standard. 


Operation 

The  counter  will  operate  on  a  fresh  9  woJt 
battery  for  several  hours.  There  is  no  power 
switch.  For  use  on  your  workbench,  just  about 
any  quality  source  of  power  will  work.  Watch 
out  for  those  wall-wart  power  supplies!  Many 
are  nothing  more  than  one  diode  with  very 
ftttle  filtering.  The  input  supply  voitage  is 
between  7  and  15  volts  DC.  The  counter  re- 
quires about  50*60  m  A, 

Set  the  rotary  switch  to  select  the  gate  time 
and  thus  the  amount  of  resolution  you  require. 
The  longer  the  gate  time,  the  better  the  reso- 
lution of  the  frequency  displayed.  The  longest 
gale  time  is  atraut  four  seconds  to  update  the 
display.  That's  rtl 

Since  the  S  fit  S  Engineering  kit  Is  so  se^f- 
contained,  it  opens  up  a  new  way  of  seeing 
things.  I've  always  used  a  frequency  counter 
to  spot  trouble.  They  make  great  sniffers  of 
RF.  The  S  &  S  Engineering  kit  has  more  than 
enough  sensitivity  to  sniff  out  weak  signals.  In 
fact,  it  could  read  the  lest  point  just  by  holding 
a  wire  near  the  input  pin. 

I  found  a  particularly  useful  task  for  the  fre- 
quency counter;  Reading  the  VFO  of  a  direct 
conversion  transceiver  You  can  also  use  the 


counter  to  display  your  operating  frequency  in 
a  superhet  receiver,  too.  In  fact,  there  are 
some  suggestions  on  how  this  may  be  accom- 
plished in  the  assembly  manual  Since  you 
don't  require  the  longer  gate  times,  and  thus 
the  four  extra  displays,  the  standard  four-digit 
unit  works  best.  I  would  bypass  the  gate 
switch  with  jumper  wires.  By  using  this 
counter,  you  can  add  an  LCD  frequency 
counter  to  your  latest  home-brew  project. 

The  t-ast  Page 

This  project  is  simple  enough  for  a  be- 
ginner to  handle.  It  would  be  best  if  you  have 
some  idea  of  how  to  solder,  what  end  of  a 
diode  is  what  and,  of  course,  the  proper 
installation  of  IC  chips.  Except  for  the  calibra- 
tion adjustment,  there's  nothing  to  touch.  If 
you  assemble  it  correctly,  it's  going  to  work. 

Johnny  Carson  has  retired,  the  USSR  is  no 
more,  and  you  don't  need  a  700  watt  switch- 
ing power  supply  to  operate  this  frequency 
counter.  Best  of  all,  you  don't  need  a  \A/V  bus 
to  carry  it  in.  The  S  &  S  Engineering  frequency 
counter  kit  is  an  excellent  value.  It's  easy  to 
build,  easy  to  operate,  and  has  all  kinds  of 
possibilities  m  your  ham  shack. 


Sell  your  product  in  73  Amateur  Radio  Today  Call  Dan  Harper  today!  1-800-274-7373 


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32  73  Amateur  Radio  Today  July,  1 994 


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SpcHisored  in  part  by  Radio  City,  Inc.  and  73  Amateur  Radio  Today. 


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73  Review 


Number  S  on  your  Feedback  card 


hy  Breckinridge  S.  Smith  K4CHE 


The  LDG  Electronics 

FC-1 

A  small,  flexible  fox  controller  and  CW I  Den 


LD6  Electronics 

1 445  Parran  Road 

St  Leonard  MD  20685 

Telephone:  (410)  586-2177 

Price  Class:  S69.95  plus  S&H 


If  you  are  a  serious  foschunter,  you  have  prol> 
abJy  tried  putting  together  your  own  loxbox* 
with  timers,  identifiers,  etc.  You  have  tried  the 
different  circuits  using  timing  capacitor  net- 
works and  different  chips,  and  you  have  prob- 
abfy  soldered  in  those  countfess  diodes  in  that 
matrix  for  the  IDer.  Recently  I  tested  the  LDG 
Electronics  Microprocessor  Fox  Hunt  Con* 
troll er/CW  IDer  board.  This  small  Maryland- 
based  company  has  devefoped  a  real  gem. 
Yes.  the  East  Coast  does  produce  some  fox- 
hunt goodies- 

Why  do  you  need  a  microprocessor  con- 
trollrng  yoor  hidden  transmitter?  What  1  want- 
ed was  a  limer/lDer  system  thai  was  small, 
reliable,  and  easy  to  change.  I  wanted  to 
spend  more  time  on  my  own  DF  equipment, 
helping  beginners,  and  not  spend  hours  build- 
ing and  lasting  numerous  timing  circuits,  I 
wanted  to  be  able  to  change  the  identification 
and  timing  cycles  of  the  hidden  transmitter  to 
suit  each  individual  hunt.  I  am  not  an  avid 
computer  enlhusiasl  but  the  LDG  ad  in  73 
said  I  could  program  this  controiler  from  my 
PC  so  I  gave  up  and  ordered  the  board.  Time 
to  join  the  microprocessor  crowd* 

The  Board 

What  I  got  was  a  small  assanMed  3.r  by 
3.6"  board  that  was  not  a  kit;  a  board  with  pro- 
fessional printed  circuit  traces  and  a  small 
plug-in  module  for  the  audio,  keying,  and 
power  functions.  Included  in  the  package  was 
over  450  pages  of  documentation  contained 
in  four  separate  handout/books,  and  a  floppy 
disk  with  numerous  programming  files  on  it* 
After  wading  through  the  information  ]  found 
the  three-page  fox  controller  sheet  and  the 
24-page  LDG  manuaL 

Reviewing  the  documentation,  I  realized 
that  what  I  had  received  in  the  mail  was  a 
foxbox  controller  and  a  small  singta*board 
computer/processor  using  the  68HC11  micro- 
processor. I  know  that  there  are  more  ad- 
vanced microprocessors  out  there  but,  again. 
you  have  to  start  somewhere.  You  can  use 
the  system  as  a  foxbox  control!er/CW  ider,  or 
do  your  own  experiments  with  the  micropro- 
cessor using  the  450  pages  of  documentation. 
LDG  also  markets  this  same  basic  board  as  a 
16-oulput  DTMF  decoder  which  requires  dit- 

34  73  i4ma^eLrrHad/o  Today*  July,  1994 


ferent  software  and  a  different  plug-in  module. 

Programming 

The  controller  arrived  with  a  test  program 
loaded.  I  recommend  you  test  the  txiard  ini- 
tlalfy  to  get  familiar  with  the  different  push-but- 
tons and  board  operations,  then  proceed  with 
your  programming.  You  load  the  LDG  disk 
program  using  their  disk  into  your  computer 
and  then  you  modify  the  FOXMCW  file  to  suft 
your  identification  and  timing  requirements. 
Their  handout  teJIs  you  which  lines  on  the  files 
to  modify,  Using  an  ASCII  file  edit  program, 
you  may  change  values  on  selected  lines  by 


typing  in  different  number  values  for  timing, 
tones*  speeds,  and  real  letters  for  the  modu- 
lated CW  Identification.  You  then  ""reassem- 
ble"  your  changes  using  the  assembly  pro- 
gram which  is  on  the  supplied  disk.  After  you 
assemble  the  program  you  can  then  send  to 
the  LDG  controller  via  RS-232  cable. 

I  told  you  I  wasn't  a  computer  person!  The 
loading  program  is  written  In  BASIC;  I  spent 
20  minutes  trying  to  type  in  the  command 
"BASICA  Bootload"  instead  of  "GWBASIC,' 
which  is  what  I  had  installed  on  my  computer* 
I  would  have  preferred  a  more  detailed  step- 
by-step  instmction  sheet  of  the  programming 


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FT-2500W 


This  new  hand 
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such  as  advance  frac? 
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This  dual  band  mobile 
features  100 
memohes.  cross  band 
repeat,  lighled 
keypad,  butlt-in 
dupiexer  and  a  small 
footprint.  Dual  walch 
capability  juunds  out 
this  50/35  wall  VHF; 
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Packed  ready    ^  ^^ 


599 


»T>« 


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,  1  ijT -ijjaii.r  I  tf4  '<|*>^*  4  fuL  4a4  n*r  ttM  ism.  i 


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Aulhorize<t  Factory  Wari  anty  Center 

We  DTroT  fBcxofY  autharlzed  wormniv  scrvicii  for  Icom,  Kenwocxl  and  Y^eau.  We  fi«rvic«  ctifmaKee  and  models,  Our  customers  may  ssf^d  any  prcdud  ivqutrtig  Aetvi^  lo  us.  itnd  ws 

wiilt!fatidlo  ii  tnr  Thom  Tinia  Is  ei  ono<$iop  sorvlcefhi^i  keepH  ourciK^iomorri  havinQ  mors  tun  than  h^sslo  m  this  liobby,  K  yiziu  noiKis  custom  cable  for  pAckaT  and  doo'l  have  lime  to 
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CIRCLE  153  ON  READER  SERVICE  CAflD 


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process,  but  the  instnictions  supplied  are  ad- 
equate .  *  Jf  I  can  do  it.  you  can  do  it 

During  your  programming  you  may  modify 
the  initial  delay  time  prior  to  startup,  the  first 
and  second  identification  messages,  and  the 
on  and  off  periods  that  wilt  be  repeated  dur- 
ing the  hunt.  LDG  included  a  second  identifi- 
cation message  feature  which  is  unique:  You 
can  have  a  push-button  on  your  foxbox  wired 
to  the  LDG  controller's  "bit  1  output/'  When 
the  first  hunter  finds  the  box,  he  pushes  the 
button  and  presto,  the  CW  message  changes 
over  to  the  iox  found,**  message,  which  will 
now  be  contfnuously  repeated  until  the  con- 
troller is  "reset"  Here  in  Delaware  we  have 
had  some  devious  hunters  who  have  moved 
the  foxbox.  In  the  case  of  tampering  you 
could  even  wire  up  a  mercury  "lilt"  switch  to 
activate  a  tampering  message  to  warn  the 
other  hunters  as  well  as  the  hider. 

LDG  mentions  to  "feel  free  to  program  and 
reprogram"  as  Ihe  EEPROM  in  the  68HC11 
has  a  life  of  10.000  cydes.*"  LDG  wBtms  you, 
and  f  will  warn  you:  Be  sure  to  make  a  copy 
of  the  FOXMCWASM  file  before  you  start 
changing  the  parameters.  If  you  get  com- 
pletely out  of  whack  you  can  always  start 
over  with  the  original  file.  Since  this  is  an 
EEPROM  you  can  remove  vollage  from  the 
unit  and  rt  wfll  Still  retain  the  information  that 
you  have  programmed. 

During  your  programming  of  the  controller 
you  are  limited  to  75  characters  total  for  the 
two  messages;  exceeding  this  limit  during 
ioading  results  rn  a  friendly  error  message  lat- 
er One  observer  during  a  hunt  stated  that  he 
thought  the  plain  CW  messages  were  boring; 
you  can  use  the  letters  "E"  "T"  to  produce 
multiple  dtts  and  dahs  and  set  up  a  rhythm 
pattern  to  break  the  monotony.  Again,  you 
can  only  use  75  characters,  and  "spaces" 
count. 

Testing 

One  handy  feature  of  LDG's  programming 
process  using  your  PC  is  a  test  command 
which  allows  you  to  test  the  board  for  your 
programming  changes  without  disconnecting 
from  your  PC. 

During  my  programming  and  testing  of  the 
board  I  found  an  error  in  the  published  com- 
putations for  timing.  The  Fox  Controller  in- 
structions used  a  value  of  130  for  each 
minute,  and  my  controller  needed  a  value  of 
114.5  for  each  minute  for  a  "tick''  value  of  1 .9 
per  second.  The  values  on  the  suppfted  LDG 
disk  were  correct  except  for  the  "tick"  value 
information.  I  talked  this  over  with  LDG  and  it 
is  my  understanding  that  they  will  correct 
their  timing  information  on  their  handouts.  For 
short  tsming  periods  this  error  is  not  critical, 
but  for  a  several-hour  initial  timing  computa- 
tion a  correct  value  must  be  used. 

The  timing  range  was  quoted  in  the  in- 
stnjcttons  to  be  from  0  to  approximately  7.7 
hours,  but  my  computations  and  actual  test- 
ing indicated  a  longer  range  of  9.5  hours.  I 
again  notified  LDG  of  this  and  appropriate 
corrections  will  be  made.  IVs  fun  to  hide  a  box 
earlier  in  the  day  and  have  it  start  several 
hours  later  on  schedule  while  you  are  at  the 


hunt  starting  site.  With  the  programmable  tim- 
ing you  can  have  multiple  boxes  start  up  in 
stages  during  the  day  as  a  complex  hunt  un- 
folds. However,  due  to  slight  variances  of  the 
Internal  8  MHz  crystal,  be  prepared  to  have  a 
slight  error  during  long  timing  periods,  and  of 
course  you  must  "arm"  the  controller  at  the 
proper  time  by  pushing  the  reset  button.  The 
perfectionist  can  time  his  or  her  own  board 
for  a  one-hour  period  and  come  up  with  the 
appropriate  corrections. 

I  have  abused  this  board.  I  left  it  laying  on 
my  desk  for  a  month  connected  to  my  PC 
with  a  9  volt  battery  dangfing  on  the  power 
leads.  1  abused  the  board  further  when  I  inter- 
laced it  to  an  old  commercial  20  watt  boat  an- 
chor. 1  hooked  the  board  up  using  unshielded 
wires  and  mounted  it  next  to  the  transmitter 
RF  section.  RF  doesn't  seem  to  affect  the 
processor  as  I  positioned  a  quartef-wave  an- 
tenna with  15  watts,  3'  away  from  the  ex- 
posed unit,  with  no  problems.  I  then  wired  the 
controller  to  the  same  power  supply  as  the 
commercial  radio  internai  power  supply  sec- 
tion, which  has  a  receive/transmit  relay  on  it 
The  inductive  krck  of  the  transmit  relay  didnH 
bother  the  board.  Tests  conducted  with  the 
traditional  hot  air  blower  and  freeze  spray 
had  very  little  effect.  Overall,  the  board  ap- 
pears to  be  rugged  and  pretty  bulletproof. 

I  thought  LDG  put  a  lot  of  thought  into  the 
hardware  design  of  their  board.  There  are 
four  of  those  little  rubber  feel  underneath  the 
board  for  shock  mounting,  and  your  main 
hold-down  bolts  go  through  the  RS-232  con- 
nector so  that  the  connector  is  secure  when 
you  plug  and  unplug  the  bulky  cable.  The  low 
power  CMOS  circuitry  can  be  powered  by  us- 
ing just  a  9  volt  battery  or  any  power  source 
up  to  20  volts.  During  testing  with  the  board 
on  the  same  power  supply  as  the  transmitter, 
the  board  voltage  regulator  continued  to  func- 
tion to  a  low  voltage  level  of  7  volts,  which  is 
handy  if  the  fox  battery  starts  to  wind  down 
during  the  hunt. 

The  push-to-talk  output  of  the  board  is  an 
open  collector  keying  transistor  which  you 
can  use  with  a  reed  relay  (Radio  Shack  274- 
232)  to  allow  flexibility  in  using  different  ra- 
dios for  the  bx,  or  if  your  radio  allows  just 
grounding  the  push-to-talk  circuit. 

The  8  MHz  clock  crystal  osctliator  emits  a 
small  signal  which  can  be  seen  with  a  spec- 
tnjm  analyzer  throughout  the  VHP  range.  On 
my  controller  the  signal  was  at  144.030, 
146.030,  146.030  and  could  be  heard  about 
20  to  30  feet  away  with  a  handheld.  If  this 
bothers  you,  you  can  shreld  the  complete  unit 
in  a  box  with  feed-through  capacitors.  The 
reason  the  harmonic  was  not  on  an  even 
MHz  is  a  very  minute  error  in  the  8  MHz  oscil- 
lator. 

Overall p  the  LDG  board  performs  as  adver- 
tised, has  lots  of  documentation,  doesn't  re- 
quire a  computer  genius  to  program,  and  tol- 
erates abuse.  It  is  easy  to  hook  up  the  power, 
push^lo-talk,  and  audio  outputs  to  your  trans- 
mitter. For  S69.95  you  can  have  an  assem- 
bled fox  controlier/CW  IDer  to  create  your 
own  personalized  system,  and  at  the  same 
time  experiment  with  a  microprocessor 


CIRCLE  194  ON  READEf^  SERVICE  CARD 

36  73  Amateur  Radio  Today  *  July.  1 994 


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A  Delayed  Video  Trigger  for 

Your  Oscilloscope 

Convert  your  surplus  scope. 


by  Joseph  A.  Consugar  KC3XM 


When  I  began  working  wiih  video  cir- 
cuits, one  of  the  firsi  things  [  learned 

is  that  you  uimnot  just  feed  a  video  signal  In- 
to aa  oscilloscope  and  e\pect  lo  see  any- 
thing  useful.  The  amount  of  time  most 
events  !  was  interested  in  took  to  occur  was 
so  short  when  compared  to  one  frame  of 
video,  it  just  didn't  work. 

This  problem  can  be  overcome  by  using  a 
delayed  video  trigger  This  is  a  circuit  that 
will  cause  the  oscilloscope  trace  !o  begin  a 
set  time  after  some  event  in  the  video  signal. 
That  event  is  usually  the  vcnical  sync  pulse, 
and  many  oscilloscopes  include  a  delayed 
video  trigger  feature.  But  what  do  you  do  if 
you  are  using  a  surplus  scope  without  this 
capability  and  don^t  want  to  buy  a  whole 
new  scope  just  to  get  this  feature?  You  apply 
a  little  ingenuity  and  build  one. 

The  Basics  of  Video 

To  understand  how  the  circuit  T  came  up 
with  works,  you  shoidd  have  at  least  some 
idea  of  the  structure  of  a  video  signal.  This 
is  by  no  means  complete,  but  it  should  sup- 
ply enough  information  so  thai  you  can  fol- 
low the  circuit  description. 

A  video  display  may  look  continuous,  but 
it  is  actually  composed  of  a  series  of  still 
pictures  thai  is  going  by  so  fast  they  all 
blend  together.  Each  of  these  pictures  is 
called  a  video  frame,  and  each  frame  is 


made  up  of  two  video  fields  thai  arc  labeled 
the  even  and  the  odd.  A  new  video  frame  is 
displayed  30  times  per  second,  so  a  new 
video  field  is  displayed  60  iinie\  per  second. 

Each  ^'idco  frame  is  made  up  of  525  hori- 
zontal lines^  w^hich  are  split  equally  between 
the  video  fields,  Displaying  262,5  lines  of 
video  in  1/60  of  a  second  means  each  line 
requires  about  63.5  micros*?conds. 

Out  of  these  262,5  lines*  only  244  of  them 
are  used  to  transmit  video  information.  The 
remaining  lines  arc  used  for  blanking  the 
display  during  picture  retrace  and  display 
synchronization.  Figure  1  shows  the  struc- 
ture of  these  lines  for  the  even  field. 

Picture  synchronization  is  performed  us- 
ing sync  pulses  that  are  included  as  part  of 
the  video  signal,  the  main  ones  being  the 
horizontal  and  vertical  sync  pulses.  Horizon- 
tal sync  pulses  indicate  the  beginning  of  a 
new  line  of  video  and  vertical  sync  pulses 
indicate  the  beginning  of  a  new  Held  of 
video.  In  Figure  1 ,  note  the  structure  of  lines 
4  lo  6.  These  arc  the  lines  when  the  vertical 
sync  pulse  occurs.  During  these  lines,  the 
sync  pulses  are  much  wider  than  normal, 
which  is  the  key  to  determining  when  a  ver- 
tical sync  puise  occurs. 

Circuit  Description 

The  steps  necessary  to  produce  a  delayed 
video  trigger  arc  illustrated  by  the  block  dia- 


/\/A, 


n 


»i 


263 


\ 


^  1 

1[ 

^ 

_ 

J        LJ        1 1        Lfc 

11 

: 

i           i 

3 

4 

i 
3 

■                                                  -m- 

a 

* 

^ 


Figure  /.  Even-fielii  structwe  duritig  she  vertical  ifUenaL 


nr 


Horizontal 

Sync 
EEtTACtli?n 


m 


H 


u 


Vertical 

Sync 

Extraction 


Divide    By 
Two 


AdjyslabiB 
Delay 


Vitfeti     In 


H«fl:EDn1dl 

Sync 


VerlicBl 
Sync 


O^liiy 
Trfggar 


Delayed 
Trigger 


Figure  2.  Deiayed-trigger  block  diagram ^ 


gram  in  Figure  2.  A  schematic  of  the  corre- 
sponding circuit  is  shown  in  Figure  3. 

In  order  to  synchronize  the  trigger  with 
the  vertical  sync  pulse,  you  must  first  identi- 
fy w  hen  The  vertical  sync  pulse  occurs.  This 
is  accomplished  by  \J\^  U2,  and  their  associ- 
ated components. 

The  video  siunal  is  taken  from  the  source 
of  Q]  (an  MPFi02  JFET  whose  purpose  is 
to  provide  buffering  for  the  video  source) 
and  fed  to  the  input  of  U 1 ,  an  LM 1 881  video 
sync  separator.  Tlie  sync  pulses  arc  extracted 
from  the  video  signal  and  appear  at  pin  2. 

The  sync  pulses  are  routed  to  U2,  which  is 
used  to  separate  the  vertical  sync  pulse  from 
the  horizontal  sync  pulses.  U2a,  RL  CI.  and 
03  form  a  one-shot  timer  that  is  triggered  by 
the  ends  of  the  sync  pulses  and  whose  nega* 
tive-going  output  pulse  is  connected  to  the 
clock  input  of  U2b,  a  D  type  tlip-Hop.  When 
the  signal  from  U 1  returns  high  at  the  end  of 
a  sync  pulse,  the  one -shot  is  triggered  and  its 
output  goes  low.  The  amount  of  time  spent 
low  is  determined  by  the  values  ol  Rl  and 
CL 

The  sync  pulses  arc  also  connected  lo  the 
data  input  of  U2b,  When  the  output  of  the 
otje-shot  returns  hiiih,  the  value  of  the  svnc 
signal  is  sampled  and  appears  at  pin  12,  Nor- 
mally, the  sync  pulse  is  narrow  compared  to 
the  length  of  the  video  line  and  the  signal 
from  Ul  is  still  high  when  the  one-shot  out- 
put returns  high.  However,  dur- 
ing the  vertical  sync  pulse,  the 
sync  pulse  is  wide  compared  to 
the  length  of  the  video  line,  so 
that  the  next  sync  pulse  has  al- 
ready begun  by  the  end  of  the 
one-shot  pulse.  Therefore,  the 
output  of  U2b  is  normally  high, 
except  during  the  vertical  sync 
pulse,  when  it  is  low-.  This  se- 
quence of  events  is  illustrated  in 
Figure  4. 

At  this  point  there  are  two 
pulses  for  each  frame  of  video, 
one  for  the  even  field  and  one  for 
the  odd  field.  To  cnstire  a  stable 
oscilloscope  display,  the  trigger 
must  be  keyed  to  the  same  field 
(i.e..  the  even  or  the  odd)  each 
time.  This  is  accomplished  by  us- 
ing the  vertical  sync  pulses  from 


Video 
Signal 


Horizontal 
Lin^O^urnber 


38  73  Amateur  Radio  Today  •  July,  1994 


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Figure  3.  Delayed-irigger  dfvuil  schematic. 


U2  as  the  clock  for  a  divide-by-two  circuit 
formed  by  U3a.  Each  vertical  sync  pulse 
causes  the  ouipui  of  U3a  tt>  change  stale. 
The  result  is  a  square  wave  that  goes  high 
once  per  video  frame  and  can  be  used  as  the 
trigger  for  the  final  delay  circuit. 

The  delay  circuit  is  composed  of  a  one- 
shot  timer  made  up  of  U3b,  R2,  C2,  and  tM, 
The  one-shot  is  triggered  each  lime  the  sig- 
nal from  U3b  goes  high  and  Ihe  pulsewidth 
can  be  varied  using  R2.  The  end  of  ihe  pulse 
is  the  external  trigger  for  the  oscilloscope. 

As  vou  look  at  the  schematic,  vou  v^Wl  no- 
lice  there  are  some  components  whose  pur- 
poses have  not  been  clarified.  Dl,  D2,  R3, 
and  C3  form  a  video  clamping  circuit  whose 
purpose  is  to  provide  DC  level  restoiulion 
for  ihe  AC-coupled  video  signal.  While  not 
strictly  part  of  the  delayed  trigger  circuit,  it 
is  useful  to  keep  the  osciltoscope  display 
stable  when  viewing  rapidly-changing  video 
signals. 


Constritetian  and  Use  of  the  Delayed 

Trigger 

The  prottjtype  for  this  circuit  was  buiit 
on  a  Radio  Shack  protoboard  using  point* 
to-point  wiring.  Another  option  would 
be  10  make  a  PC  board  according  to  the 
design  in  Figure  5.  Or  you  can  order  one 
already  drilled  and  etched  for  S4.25  plus 
$1.50  S  &  H  per  order  from  FAR  Circuits, 
18N640  Field  Court,  Dundee,  IL  60118. 
]  recommend  that  you  build  the  stages 
separately  and  make  sure  each  is  work- 
ing correctly  before  proceeding  to  the 
next. 

When  you  have  completed  construction, 
connect  a  9V  battery  to  the  power  connec- 
tions and  a  video  signal  lo  J 1,  Adjust  R2  to 
its  minimum  value  and  examine  the  delayed 
trigger  output  at  J3  with  an  oscilloscope. 
You  should  see  a  series  of  very  short,  nega- 
tive-going pulses  whose  ^vidih  increases  as 
R2  is  turned  clockwise. 


Once  you  have  the  delayed  trigger  work- 
ing, adjust  your  oscilloscope  to  accept  a  pos- 
itive-going  external  trigger.  Set  R2  to  ap- 
proximately halfway.  Connect  the  trigger 
signal  at  J3  to  the  oscilloscope *s  external 
trigger  input  and  the  video  signal  at  J2  to  the 
vertical  input.  Adjust  the  oscilloscope  time 
base  so  that  there  are  three  or  four  lines  of 
video  displayed  on  tlic  screen.  As  you  vary 
R2,  you  should  see  different  parts  of  the 
video  signal  on  the  screen.  The  values  given 
for  R2  and  C2  should  allow  you  to  var)*  the 
dela\'  from  approximate K  zero  to  about  one- 
and-one-half  video  fields. 

Final  Notes 

When  you  turn  on  the  circuit  and  cnnneci 
a  video  signal,  the  trigger  will  randomly 
latch  onto  one  of  the  video  fields.  If  the  field 
being  displayed  is  not  the  one  you  want  to 
examine,  move  SI  to  its  opposite  position 
and  the  opposite  video  field  will  be  dis- 


*  •  ' 

S     •  * 

i     •  * 


I     * 

*  ; 
■  • 


«  * 


Horizontal    Sync 
Pulses    (01,    Plffil) 


On«-S)tot    Output 
(U2a,    PinS) 


Vertical    Sync 
Pulse    (U2b.    P]it12} 


Figure  4,  Venical  sync  pulse  extracutm  process. 


Parts  List 

R1 

3.3k 

R2 

1  meg  potentiometer,  lir^ar  taper 

R3 

Ik 

CI 

0.0047  |jF 

C2 

0.033  |jF 

C3 

0,1  mF 

D1.D2,D3,D4 

1 N91 4  silicon  dtode 

Q1 

MPF102JFET 

U1 

LM1381  video  sync  separator 

U2.U3 

4013  D  type  tip-f  op 

J1.J2J3 

RCA  phono  jack 

SI 

SPOT  swjicn 

Note:  Resistors  are  all  5%  1/4  watt.  Capacitors 

are  all  poiyesti 

?f  type. 

40  73  Amateur  Radio  Today  •  July,  1 994 


XKC3XM 


IN 


h 

01 

^  L 

1      1    » 

leacr;  > 

mm 

'L 

^- 

JLj 

x 

''T' 

s 

"  L 

w 

^ 

y2 

o 

AV 

9VDC 


S1 

Mm 

.31 


UG 


^ 


played.  There  is  no 

way  to  determine 
which  field  will  be 
displayed  when 
you  turn  the  circuit 
on,  but  vou  can  al- 
wavs  get  to  the  one 
you  want. 

For  those  people 
who  are  familiar 
with  the  LM18S1, 
yoy  may  wonder 
why  T  didn't  lake 
advaniagc  of  some 
of  its  other  features 
(e,g„  the  even/odd 
field  indicator).  It 
has  been  my  expe- 
rience that  in  order 
to  fully  utilise 
these  features,  the 
video  signal  being 
examined  should 
conrorm  closely  to 
the  video  standard. 
Unfortuna  tel  y, 
some  video  sources 
(c.g«,   VCRs  and 

camcorders}  take  liberties  with  that  standard.  The  circuit  as  presented  was  designed  so  that, 
with  hope*  it  would  work  with  as  many  of  these  near  misses  as  possible.  If  you  work  pri- 
marily with  standard  video,  I  encourage  you  to  take  advantage  of  the  additional  features  of 
the  LMi881  and  share  the  results  with  the  rest  of  us* 


VSDEO 
TRGER 


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73  Amateur  Radio  Today  •  Jufy,  1 994  41 


Ntimlier  1 0  on  your  Fsedback  card 


M  ultiband  Half- Wave 
Delta  Loop  (MHDL) 

A  simple  20- 1 0  meter  antenna  with  an  80-30  meter  bonus 


by  James  W.  McLelland  WA6QBU 


While  looking  through  my  books  for 
some  kind  of  smull  antenna  thai  would 
fit  in  the  attic,  I  happened  upon  a  short  de- 
scription of  half-wave  loops.  Tve  always 
preferred  full-wave  loops,  but  a  20  meter  one 
woijldn*t  fit  in  my  17  \  25"  attic  given  the 
fact  tltai  1  needed  to  stay  away  from  oulside 
rain  gutters.  Hushing,  downspouts,  vents  and 
a  chimney.  As  luck  would  have  it,  however.  I 
discovered  thai  a  half- wave  loop  fus,  with 
room  to  spare  (Fve  hung  it  on  my  classroom 
wall  as  well).  While  half-  and  full-wave 
characieriHtics  are  quite  difterent  from  each 
other,  with  the  details  worked  out,  the 
MHDL  has  proven  itself  to  be  an  effective 
indoor  reference  antenna  for  the  upper  {20- 
10  meter)  HF  bands.  (By  ihe  way,  there's  a 
slick  trick  you  can  use  to  make  it  work  on 
SO' 30  meters  as  well.)  It's  easy  to  build,  re- 
quires no  alignment  and  the  XYL  can*l  see 
iL  Try  it,  This'll  be  the  easiest  antenna 
you've  ever  built. 

Description 

The  loop  is  cut  for  a  half  wave  on  20  me- 
ters. Half-wave  loops  have  a  very  high 
impedance,  in  the  order  of  2,f)0D  ohms,  so  I 
needed  to  bring  the  impedance  down  to  a 
more  workable  value.  Using  a  quarter-wave 
(including  a  velocity  factor  of  0.80)  trans- 
mission line  transformer  will  drop  the 
impedance  to  ahout  50  ohms-  1  used  300 
ohm  twin  lead  (Radio  Shack  15-1153)  be- 
cause it  works  well  into  a  tuner,  is  inexpen- 
sive and  has  low  loss.  On  10  meters,  the  20 
meter  half  wave  becomes  a  full  wave  and  the 
impedance  drops  to  about  100  ohms,  the 
fecdline  is  now  half-wave  and  acts  as  a  Irl 
transformer,  which  your  tuner  will  have  no 
trouble  matching.  I  also  found  that  my  tuner 
could  easily  resonate  and  match  the  MHDL 
on  17,  15,  and  12  meters.  If  you  use  a  3/4- 
wavelcnglh  fecdline,  you  can  also  get  an  SO- 
SO  meter  bonus  bv  shortins  the  two  feedlinc 
wires  together  and  tuning  it  as  a  top-loaded 
vertical.  This  gives  you  a  vertical  3/4  wave 
on  30  meters,  a  half  wave  on  40  meters  and  a 
quarter  wave  on  80  meters.  However,  you 
must  use  a  ground  to  make  this  mode  effec- 
tive. By  the  way.  it's  about  1/8  wave  on  160 
meters  and  vour  tuner  niisht  be  able  to  add 

42  73  Amateur  Radio  Today  -  July.  1 994 


enough  inductanee  to  make  it  resonate.  Any- 
way, it's  worth  a  try. 

Construction 

Using  insulated  #16  or  #18  gauge  strmded 
wire,  cut  the  loop  to  35'  4"  (see  Figure  1). 
Now  cut  the  300  ohm  feedline  to  odd  mulli- 
pies  of  13'  S"  (exactly  4  r  for  the  80-30  meter 
bonus).  Solder  the  feedline  to  the  loop  ends 
and  insulate  with  shrink  tubing.  Then,  to 
connect  it  to  the  balun  on  my  tuner,  I  in- 
stalled two  banana  plugs  (the  kind  that  plug 
into  each  other)  on  the  end  of  6"  pigtails^  sol- 
dered them  to  the  twin  lead,  and  then  insulat- 
ed them  with  shrink  tubing.  You'll  be  done 
with  the  construction  phase  in  less  than  an 
hour 

Installation 

This  ts  the  part  where  you  can  really  get 
creative.  You  might  even  hide  ihe  feedline 
and  convince  the  XYL  thai  your  MHDL  is  a 

IT 

rosebush  trellis,  bui  then  you'H  have  lo  plant 
and  take  care  of  the  roses.  I  opted  to  bang 


mine  horiitonially  from  the  rafters.  There  is 
no  exact  shape  requirement  except  to  have  as 
much  area  as  possible.  I  like  equilateral  trian- 
gles, but  squares,  diamonds,  circles  and  rect- 
angles work  just  fine.  Changing  the  shape 
varies  the  frequency  somew^hat  (plus  or  mi- 
nus 1/2  MHz  or  so)  but  I  just  let  my  tuner  fix 
it.  More  importam  is  that  the  loop  fits  the 
space  you've  got  no  matter  what  it  looks  like 
and  what  anele  it*s  mounted  at — vertical, 
horizontal,  or  somewhere  in  between.  One 
warning:  Slay  away  from  metal  objects  with 
the  MHDL  and  feedline.  and  mount  it  with 
some  kind  of  insulating  material.  If  you  have 
extra  room,  try  a  venical  and  a  horizontal 
model,  at  least  for  20-10  meters.  Being  able 
to  switch  back  and  forth  can  really  be  dra- 
matic because  the  angle  of  radiation  as  well 
as  the  polarity  will  be  different.  Lastly,  if  you 
go  for  the  80-30  bonus,  the  feedline  should 
be  somewhat  vertical  and  stretched  oui,  bui 
the  higher  part  could  be  horizontal  and  work 
OK  in  anv  case,  it's  a  lot  better  than  nothing 
and  it^s  all  hidden  indoors. 


41' 

300   Ohm  Twin   Lead 


To  Balun 
And  Tuner 


Figure  1 .  The  MHitilxim!  Half -Wave  Delta  Loop. 


Parts  List 


Quietffex  #14  antenna  wire 
KHowan  300  ohm  twin  lead 
Stirtrvk  tubing,  2/8' 
Stifinik  !ubing.  ^'16" 
Banana  plugs 
Dacron  line 
Egg  insulators 


36' 
4V 

r 
r 

2 

50" 
4 


Note:  Alt  parts  needed  to  build  this  antenna  can  be  obtained  by  ordering  the  Mufliband  Hall -Wave  DeHa 
Loop  Expenmantef's  Kfl  from  Antennas  West,  1500  N  150  W.  Provo  UT  84604:  TeL  (801)  373-8425-  \n\w 
dudory  price  w/shipping  (40%  discount  tor  73  readers):  $24. 


There  really  isn*t  an}thing  thai  you  need 

to  tweak  oil  the  MHDL,  Siirc,  you  could  use 
a  lancy  antenna  bridge  to  irim  it  for  20  and 
10  meters  once  it*s  installed*  but  you*ve  got 
to  use  a  tuner  for  ihe  other  bands  an%  wav.  so 
why  bother?  For  20-10  meters,  ju.st  connect 
it  to  the  balun  tcmiinaJs  and  tune  for  mini- 
mum SWR  with  the  lowest  power  you  can 
(check  for  a  cbar  frequency  first),  then  look 
for  a  QSO.  On  80  and  40  nteiers,  plug  both 
banana  plugs  together  into  the  single -ended 
"wire"  tenninal  on  the  timer  and  connect  it  lo 
the  best  ground  you  can  gel.  For  easy  band 
changes,  I  keep  my  setting  wrinen  on  a  card 
next  to  the  tuner.  It  tunes  quite  broadly  su 


me  setting  for  each  band  gets  me  close 
enough  to  gel  started,  and  then  touching  it  up 

is  very^  easy. 

Testing 

Does  it  work?  You  bet  it  does!  Tve 

worked  as  far  west  as  central  Russia  and  as 
far  east  as  Czechoslovakia,  or  is  it  the  other 
way  around?  North  to  Alaska,  and  south  to 
Argentina.  New  Zealand  and  Australia  were 
also  no  problem,  OK,  OK!  I  know.  The 
bands  aren't  as  good  as  they  used  to  be,  but  it 
still  is  a  pretty  good  antenna  for  being  in  my 
anic  and  if  you  don't  like  it  maybe  the  XYL 
can  hang  cioihes  on  it — hey,  wail  a  minute!  1 
think  Fve  got  an  idea. 


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^^mff,ul^J!7Zn^ytii,i^n    (516)328-7501  FAX (516) 328-7506 


73  Amateur  Radio  Today  •July,  1994  43 


Nuinbef  t1  on  your  Feedback  card 


The  Improved  Resonant 

Feedline  Dipole 

A  compact,  low  impedance,  end-fed  HF  antenna  that  needs  no  tuner! 


by  James  E.  Taylor  W20ZH 


The  end-fed  RASER  antenna  described  in 
73  Amaieur  Radio  (September  1992,  pp* 
8-14)  utUtzed  the  RFD  (Re&onani  Feedline 
Dipole)  approach.  TTiis  concept  has  drawn 
an  cnthusiaslic  lesptmse  from  hams  through- 
oui  the  cooniry.  li  achieves  an  end-fed 
dipole,  or  a  RASER,  for  any  band  desired 
asin^i^  a  coaxkil  feedline  and  wiihoui  a  mnen 
It  has  been  praised  by  many  who  have  site 
rchLnciions  which  prec[iide  the  use  of  the 
custonnary  dangling  center  feedline,  A 
unique  feature  of  ihL'se  antennas  is  the  use  of 
the  T-chokc — eg.:  a  13'lum  coi!  of  coax 
which  is  .suspended  at  ihe  input  end  of  the 
radiator  If,  however,  you  find  such  a  coil 
cumbersome  the  present  article  offers  help! 

The  RFD  Concept 

As  mentioned  in  the  previous  articles,  an 
obvious  approach  to  the  electrical  isolation 

of  the  input  end  of  the  dipole  might  involve 
the  use  of  a  current  balun.  However,  calcula- 
tion showed  that  this  direct  approach  would 
not  provide  sufficient  impedance.  At  that 
time  1  chose  to  use  the  somewhat  more 
bulky  T-choke  method  of  isolation.  Never- 
theless, the  idea  of  making  a  more  compact 
choke  was  rekindled  when  I  found  an  article 
in  my  files  by  Joe  Reisert  WIJR  (Ham  Ra- 
dio. September  1978,  pp.  12-15).  Thai  arti- 
cle described  **a  new  type  of  balun"  which 
featured  a  high  permeability  toroidal  core 
wound  with  coaxial  cable  using  opposed 
windings  for  reduction  of  external  field,  as 
showTi  in  Figure  L  Based  upon  that  idea,  T 
made  a  few  comparative  impedance  calcula- 
tions, which  were  encouraging.  Experiments 


then  led  to  a  simple  practical  design  in 
w  hich  the  T-choke  is  replaced  by  a  compact 
box, 

I  will  describe  the  final  design  of  the  RFD 
antenna  for  the  80  meter  band  in  some  de- 
tail, and  tabulate  the  results  of  the  calcula- 
tions in  the  "Calculations"  sidebar.  Also  in- 
cluded is  a  tabulation  of  the  calculated  num- 
t>cr  of  turns  and  lengths  of  the  dipole  halves 
for  ihe  other  popular  HF  amaieur  bands. 

The  Design 

In  the  previous  design  of  the  RFD  the 
self- resonant  T-choke  served  two  related 
functions:  It  gave  the  high  impedance  re- 
quired to  isolate  the  end  of  the  dipole,  and  it 
provided  the  reactance  which  tuned  the  sys- 
tem to  resonance,  thereby  enabling  an  excel- 
lent impedance  match  to  the  feedline.  In  the 
improved  RFD  design  these  functions  are 
achieved  by  adding  a  fixed  resonating  ca- 
pacitor in  parallel  with  a  winding  of  coax  on 
a  toroidal  core,  as  in  Figure  I,  First,  calcula- 
tion shows  that  if  we  use  the  Type  T-200-2 
powdered  iron  core  commonly  used  for 
baluns  in  this  frequency  range  the  induc- 
tance would  be  an  order  of  magnitude  lower 
than  that  for  the  T-choke.  Even  two  such 
coils  in  series,  tuned  to  resonance  using  a 
264  pF  capacitance,  is  low^er  by  a  factor  of 
five.  In  spite  of  this  I  temporarily  wound 
two  13- 1/2- turn  coils  on  these  cores  for  pre- 
liminar)'  experiments.  The  resuhs  confirmed 
the  feasibility  of  the  approach  but  tlie  mea- 
sured common  mode  current  on  the  feedline 
was  too  high-  (The  MFJ  H-field  Antenna 
Probe  is  convenient  for  comparing  these  cur- 


rents). However,  during  this  test  an  impor- 
tant fact  was  determined^^/j  order  to  get  the 
desired  1:1  SWR  it  was  necessary  w  place  a 
current  bahm  in  the  line  ahead  of  the  tuned 
coils.  For  this  I  used  a  2C)-tum  bifilar  coil  on 
a  T-200-2  core.  This  cuiteni  balun  provides 
impedance  balance  relative  to  RF  ground. 

Further  review  of  the  Amidon  data  sheets 
indicated  that  we  must  consider  ferrite  mate- 
rial, which  provides  higher  penneability,  in 
order  to  get  the  higher  inductance  desired. 
However  this  comes  at  the  expense  of  some 
reduction  in  lemperature  stabiliiy.  The  FT- 
240^  1  core  w  as  chosen  for  our  desired  pow- 
er levels  and  frequency  range.  This  core  has 
an  initial  pcmieability  of  125,  and  with  a 
core  o,d.  of  2.4  inches  it  should  handle  a 
kilowatt  of  povvcr  without  excessive  heating. 
The  calculation  of  inductance  of  a  12-tum 
coil  on  such  a  core  gave  a  value  of  25  micro- 
henries— much  greater  than  that  of  the  pow- 
dered iron  cores  and  even  greater  than  that  of 
the  RFD  T'Chokc.  Since  the  loss  resistance  is 
roughly  a  factor  of  five  less  than  that  for  the 
original  RFD,  the  calculated  prognosis  for 
the  Improved  RFD  is  very  promising!  (See 
the  Coil  Tester  comments  at  the  end  of  this 
article.) 

Const  ruction  and  .\djustmcnt 

For  the  fmal  coil  I  w^ound  6  -f  6  turns  of 
RG-8(M),  field-opposed,  on  an  Amidon 
Type  FT'240-61  toroidal  core  (see  Figure  1). 
This  coil  was  mounted  in  a  6"  x  3-3/16"  x 
1-7/8"  plastic  box  along  with  the  current 
balun  referred  to  above  and  the  tw^o  coax 
sockets,  as  indicated  in  Figure  2.  For  the 


PhoioA.  An  early  version  of  ihe  "box. 
44  73  Amateur  Radio  Today  *  July,  1 994 


ff 


Photo  B.  A  plastic  pi  I!  InHtle  does  the  trick. 


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simple  bifilar  currenl  balun  [  wound  20  turns 
of  sheathed  bell  wire  on  the  T-200-2  core, 
shown  schematically  in  Figure  3.  The  gener- 
al packaging  is  shown  in  Photo  A,  which  Is 
of  an  early  model.  Figure  4  show  si  the 
schematic  diagram  of  the  circuit.  The  sim- 
plicity of  the  circuit  is  apparent — other  than 
wire  and  coaxial  cable  fittings,  there  are  on- 
ly five  parts! 

I  have  found  that  a  plastic  pill  bottle  (the 
popular  amber-colored  cylindrical  one  with 
the  locking  cap)  makes  a  very  useful  center 
insulator  for  this  type  of  dipole.  1  mounted 
SO-239  sockets  on  the  bottom  and  the  top  of 
the  box.  Connections  are  as  indicated  in  Fig- 
ure 5.  Photo  B  shows  this  compact,  rugged 
assembly.  The  unit  can  withstand  a  surpris- 
ing amount  of  tension  and  the  parts  are  con- 
veniently disconnected,  when  desired.  Fig- 
ure 6  shows  the  complete  antenna. 

The  only  adjustment  required  was  the 
choice  of  the  tuning  capacitance  connected 
across  the  coil  of  coax  on  the  ferrite  core.  I 
made  a  preliminary  adjustment  by  using  an 
air  variable  across  the  coil  on  the  bench,  and 


Photo  C.  The  radiator,  suspended  hy  two  40-foot'high  masts.  The  box  is  at  the  lefthand  mast 
and  the  center  insulator  is  near  the  righthand  mast. 


RG-a    (Minifoam) 

6  +  6  Turns  Opposed 


Ferrlta   Core 
FT-240-61 


Figure  L  The  Improved RFD  Antenna's  coil. 


using  the  coil  tester  described  at  the 
end  of  this  article.  I  then  made  the 
final  adjustment  with  the  antenna 
in  pUce  and  with  the  plastic  box 
lowered  to  stepladder  height,  using 
an  SWR  bridge  to  indicate  1:1 
SWR,  These  adjustments  agreed  to 
within  about  10%.  The  air  variable 
was  then  replaced  with  fixed  silver 
micas  and  the  box  was  raised  to 
normal  height.  (Since  the  voltage 
across  this  capacitor  is  high  I 


SO-239 


Tuning  Capacitors 
Selected   For 
Frequency 


Enclosure:    RS-270-223 


Tuned  Coif 
6  +  6  Turns 
RG-8   (M) 


Current   Balun 
20  Turns 
Bifilar 


J 


SO-239 


placed  two  equal  capacitors  in  series-)  For 
my  installation  50  picofarads  (2  x  KM)  pF  in 
series)  brought  the  resonance  within  1 5  kllz 
of  the  desired  frequency  of  3,953  kHz. 

Results 

The  adjustment  and  operation  of  the  Im- 
proved RFD  Antenna  on  80  meters  was 
straightforward  and  satisfactory  in  all  re- 
spects. The  radiator  was  suspended  between 
the  two  40-fooi-high  masts  which  support 
the  two  RASER  gain  dipoles  at  W20ZH, 
This  can  be  seen  in  Photo  C,  where  the  box 
is  at  the  lefthand  mast  and  the  center  insula- 
tor is  near  the  righthand  mast.  The  '^termina- 
tor"  half  of  the  dipole  slopes  downward  off 
of  the  photo  to  the  right.  (The  segmented 
sections  sloping  out  of  the  photo  from  the 
righthand  mast  arc  not  part  of  this  antenna 
system.) 

It  was  interesting  to  observe  the  action  of 
the  tuning  capacitor  in  limiting  the  shield  ra- 
diation and  matching  the  radiator  to  the 
feed  line.  The  shield  current  was  indicated  by 
the  MFJ  H-field  probe  and  the  match  was 
measured  by  an  SWR  bridge  while  turning 
die  air  variable  capacitor.  At  resonance  the 
shield  current  showed  a  sharp  null  Also,  the 
SWR  was  a  flat  1:1  at  a  point  slightly  off 


To  Tuned 
Coax  Coil 


20  Turns  Bifilar 
(40   Turns   Total) 

T  =    20  Turns  Bifilar 

On  Am  id  on  T-200-2 
Powdered  Iron  Core 


From    Transceiver 


Figure  2.  Connect  the  transceiver  to  the  bottom  of  the  box. 


Figures.  Schematic  for  the  current  balun. 


46  73  Amateur  Radio  Today  •  July,  1 994 


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To  Oipole 

F«edline 


6+6  Turns 
RG-G(M)     On 
FT-2^0-61 
Toroidal  Cora 


50-239 


50   pF 

(Selected   For 
Desired    Fle^onance) 


Currenf  Bslun 
(Rguro  3^ 


30*239 


From  Transceiver 


Figure  4.  Schematic  for  the  Improved  RfDs 
box. 


Specifications  for  Other  Bands 

Band 

Freq.         Turns 

DIpole  Half  Length 

160m 

1.9              17 

123'2'' 

80m 

3.954           12 

59"2" 

40m 

7.263           d 

32'3" 

2Qm 

14.29            7 

16'5" 

17in 

18.14            6 

12'ir 

15m 

21 .38            5 

10'ir 

10m 

28.05            4 

8'2" 

resonance,  as  expected.  Noise  bridge  mea- 
surements confirmed  this  resonunt  frequen- 
cy and  indicated  an  input  of  52  ohms.  The 
measured  bandwidth  of  the  sysLem  was  170 
kHz  between  ihe  "SWR  =  1,2"  points,  which 
is  very  accepiablc.  The  common  mode 
shield  current  was  appreciably  less  than 
for  a  standard  well-balanced  center-fed 
dipole.  Stations  worked  reported  no  differ* 
ence  in  signal  strengtlis  between  these  dipole 
antennas^ 

Conclusion 

The  Improved  RFD  Antenna  is  an  end-fed 
dipole  using  coaxial  cable  without  a  tuner.  It 
achieves  the  same  advantages  as  the  original 
RFD  system,  while  replacing  the  T-choke 
coil  with  a  compact  t>ox.  It  also  provides  a 
more  convenient  method  of  adjustment  to 
resonance. 

I  wish  to  acknowledge  the  patience  of  the 
number  of  hams  who  gave  signal  strength 
comparisons  which  confirmed  the  viability 
of  the  design. 

Coil  Tester 

Michael  Covington  {73  Magazine.  Sept, 
1990,  pp.  48*51)  described  a  simple  coil 
tester  which  gives  a  direct  measurement  of 
the  resonant  frequency  of  a  parallel -tuned 


Lock-Top   Pill   Bottle 
2-1 /2"L   X  1-1 /4«   OD 


SO-239 
To  "Injector" 


50^239 


To  'Terminator 


.fi 


Figure  5.  Center  insulator  assembly. 


1 

RG-8(M) 
5§'    2^1  4" 

Antenna    Wire 
59"    2-1/4" 

^ 1 

n 

^^ 

-^  M-359 

^^^^ 1 

\j 

\ 

f 

Support 

^  Box 

(Figure   2) 

Center   Insulator 
(See  Figure  5) 

Insulator 
Support 

Feedllne 

Figure  6.  Improved  RFD  Antenna  {for  J.95S5  MHz}. 


Parts  List 

De&crlptlon 

Part  Number 

Optional  Supplier 

1  ferrite  com 

FT  240-61 

AmidOn  Assoctales 

1  powdered  iron  co^ 

T-2CK>2 

Aiiiick>n  Associates 

1  enclosure  box 

270-223 

Radio  Shack 

1  piastre  pill  box 

1*1M'^0.d,.  2-1/2"  H 

Any  pharmacy 

Silver  mica  caps 

Assorted  (ioo/$5) 

Fertiks,  5400  Ella  St.,  Phi  a.  19120 

Antenna  wrfe 

#14  Stranded 

Radio  Shack 

4  coax  sockets 

SO-239 

Radio  Shack 

5  coax  plugs 

K-259 

Radio  Shack 

5  coax  reducers 

UG-176 

Radio  Shac*^ 

1  right  angle  conn* 

M-359 

Radio  Shacl< 

Coaxia  cabe 

RG-8  {MnifoamJ 

Radio  Shack 

Twin  bell  wire 

(Sheathed) 

Any  home  supplier 

Calculations 

Kern 

Equption 

Value 

13  Tum  TChoke: 

L=aXn=XJ  = 

20|jH 

^i  (OLD^  - 

25X10^1l1  fOLO) 

2x  13.5  Turn  T200-2: 

L  =   1Q"^X|Sf^XALX2  = 

4.3  pH                                      1 

(i.e.  IRFDIJ 

^T  (RFD1>  " '-'^   ^   ^1    - 

2.4  X  10   m,  {IHFD1) 

6+6TumFR-240-61: 

L  ■  10"*  X  N^  X  Al  = 

25|jH 

{I.e.  IRFD2) 

^(IRFD2>  =    UC  X   R^  = 

64  X  IOVr,  (»f,to2> 

Z  Comparison: 

2tfF|FDij/2j^pjpQ2)    = 

0.2S 

^t(iRFDa)  '^i(RFDl)    - 

12.5 

coil.  This  tester,  together  with  my  Alfa  digi- 
tal muliimeter  (which  measures  frequency 
up  to  20  MHz)  gave  a  direct  preliminary 
measuremem  of  this  antenna's  tuned-coil 
frequency. 


Core  Kit 

Tlic  two  toroidal  cores  for  the  Improved 

RFD  are  available  as  a  kit  from  Amidon  at 
a  reduced  price  of  S12  by  referring  to  this 
article. 


48  73  Amateur  Radio  Today  July,  1994 


l?T7y  LOOP 


Number  t2  on  yow  Ffeedback  card 


Marpf.  Leavey,  M.D.,  WA3AJR 
€  Jenny  Lane 
BaiUmoreMD  21208 

Over  the  past  few  nrionths.  we  have 
looked  at  a  few  shareware  pfograms 
tor  FHTY.  This  month,  let^s  take  a  look 
at  a  commercial  package— a  package 
thai  offers  quite  a  bang  for  the  buck. 

The  program  is  BMK-MULTY,  a  PC 
program  for  running  RTTY  with  an  ordi- 
nary "dumb"  terminal  unrt  and  an  IBM- 
compatible  computer.  Developed  by 
G4BMK,  who  has  been  wriling  RTTY 
SOftweie  for  nnany  years,  this  progmin 
takes  advarrtage  at  the  processing 
power  In  the  persortal  compuler  lo  inte- 
grale  the  functions  of  a  terminal  node 
controller  into  the  software. 

With  this  setup^  some  of  the  prob- 
lems associated  with  the  hardware  of  a 
TNC.  such  as  extra  RF  noise,  is  ellmi- 
nated.  This  presumes,  of  course^  that 
your  computer  is  adequately  shiekJKJ. 
Since  the  computer  itseif  is  the  TNG. 
communicatifkg  with  the  demodulator  is 
Integral  lo  the  system,  eHminaling  con- 
cerns over  intemat  baud  rate,  data  bit5» 
and  the  fika 

Lets  take  a  fook  at  this  package 
and  see  just  what  it  can  do.  First  off,  as 
noted,  it  will  run  on  just  about  any  PC- 
compatible,  from  the  oldest  8088  run- 
ning at  4.77  MHz  to  the  latest  superhot 
screamer  Some  highly  intense  modes, 
sucti  as  PacTOR  and  SSTV,  however, 
may  not  run  well  on  a  sk^w  machine. 
While  not  rated  to  run  under  Windows, 
some  users  have  been  abEe  to  make 
this  work  with  e  fast  computer  and  full 
screen  display. 

I  have  alluded  to  the  modes  that 
BMK-MULTY  supports,  so  I  suppose  I 
should  give  you  some  details.  How 
about  fiTTY,  CW,  AMTOR  and 
PacTOR,  with  a  standard  demodulator, 
such  as  the  CP-i  we  have  been  talking 


Amateur  Radio  Teletype 


about,  or  a  Hal  ST-5  or  ST-6.  Flesh er 
TU-170  or  TU'470,  iRL  FSKOOOO, 
Heath  HD-3030.  or  even  an  okl  honfie- 
brew?  There  is  ever  an  extended  au- 
dio package  that  includes  an  audio 
spectrum  anatyzer.  with  reception  of 
HF  WE  FAX  and  SSTV. 

A  "Logger^  modute  includes  a  call- 
sign  and  QSO  database,  whlcti  oper- 
ates within  the  communications  pro- 
gram. Captured  callstgns  that  are  al- 
ready in  the  database  are  so  indicated, 
and  a  poo- up  window  is  available  to 
enter  QSO  data  as  needed. 

Mulli'Sampling  algorithms  jn  both 
the  RTTY  and  CW  modes  are  used,  to 
ensure  the  best  possible  reception  un- 
der the  most  difficult  conditions.  The 
display  can  be  configured  to  the  user's 
preference,  whether  a  split-screen  dis- 
play with  separate  receive  and  transmit 
windows,  or  a  Simulated  teleprinter, 
v^th  ali  comtiined  in  one  display.  Func- 
tions and  featuTes  are  accessed  with 
function  and  ALT  key  combinations. 

BMK-MULTY  is  the  only  commer- 
cially available  software  that  I  am 
aware  of  that  implements  AMTOR  with 
a  dumb  terminal  unit.  While  using  ad- 
vanced programming  techniques,  the 
program  is  capabfe  of  surpassing  the 
performance  of  compromise  designs 
within  multi-mode  controllers. 

Another  mode,  PacTOR,  combines 
the  features  of  Atn^OR  and  packet  ra- 
dio. Unlike  straight  packet.  PacTOR. 
which  is  highly  effective  on  the  HF 
bands,  runs  at  too  or  200  baud,  de- 
pending on  the  conditions.  With  data 
compression.  PacTOR  can  achieve  da- 
ta transfer  rates  more  than  three  times 
higher  than  AMTOR.  With  handling  of 
the  full  ASCII  character  set,  PacTOR 
allows  full  text»  and  even  binary,  data 
transfer,  all  with  the  lowest  chance  for 
error. 

Now,  I  have  Indicated  that  BMK- 


MULTY  works  wiffi  almos!  any  ganieii 
variety  RTTY  d^modutator.  But  what 
about  the  ham  who  has  invested  in 
a  muUimode  controller  Many  RTTY- 
active  hams  no  longer  have  an  ST-6 
on  the  shell  Well,  Schnedler  Systems, 
the  source  for  8MK-MULTX  has  pro- 
duced an  adapter  board  for  the  AEA 
PK-232  which  allows  access  ol  the  mo- 
dem section  of  the  PK-232,  bypassing 
the  TNC  and  data  processing  logic 
buifl  fnto  the  box.  While  this  might 
seem  like  a  step  t^ckward.  the  truth  is 
thai  for  the  modes  that  8MK*IWULTY 
supports,  this  reaJly  does  create  an  en- 
hancement. 

The  adapter  Itseff  Is  a  small,  "L** 
shaped  printer  circuit  board  that  is  in- 
stalled as  a  pass-through  device  be- 
tween the  PK-232  and  the  computer.  A 
short  jumper  connects  to  I  he  "external 
modem"  connector  on  the  back  of  the 
PK-232,  and  inside  the  PK-232.  shwt- 
ing  bkjcks  are  installed  to  change  the 
logic  of  data  ftow,  A  push-button  on  the 
board  sets  things  back  to  "nonrtaE"  for 
conventional  PK-232  operation,  such 
as  with  packet 

Now.  you  can  order  all  of  this  from 
Schnedler  Systems.  AC4IW,  25  East- 
wood Road.  P.O.  Box  5964.  Ashevllle, 
North  CaroKna  28813.  The  base  com- 
mufik:ations  package,  wt^lch  includes 
AMTOR.  RTTY,  CW.  and  the  logger 
sells  for  $95.  The  base  package  plus 
PacTOR  is  SI 45.  The  base  package 
plus  the  extended  audio  package  is 
S140.  And  all  three  packages  together 
go  for  $175.  The  PK-232  adapter 
board  is  S49.  These  prices  are  correct 
as  of  this  writing,  and  do  not  include 
shpping.  1  would  advise  you  lo  contact 
Schnedler  Systems  for  cun-ent  informa- 
tion on  phctng.  shipping  and  availabili- 
ty, letting  them  know,  of  course,  that 
you  read  about  it  in  73  magazine's 
"RTTY  Loop"! 

Now,  here's  a  follow  up  to  nr^tehaf 
we've  covered  tn  recent  months.  I  re- 
ceived an  E-mail  message  from  John 
Skubick  K8JS  via  America  On-line. 
Jack  reminds  us  that  computer  ports 
are  fairly  standard.  When  looking  at 
devk;es  such  as  modems.  TNCs.  print- 
tfS.  and  the  like,  tf  rt  can  pJug  into  the 


seriat  port  of  a  PC-compatibfe  ^Mmput- 
er  and  work,  than  this  same  hardware 
Should  work  as  well  on  an  AMIGA 
computer,  or  any  other  cofnputer  that 
supports  standard  port  pin  assign- 
ments. Thanks  to  Jack  for  that  tip, 
which  he  directed  to  me  through  Inter- 
net- 

And,  while  we're  on  the  subject  of 
terminal  units,  here's  a  question  re- 
ceived via  E-mail  on  Delphi:  Emory 
WA4TTO  has  been  reading  73  maga- 
zine Since  1976,  Back  in  197a  or  1979. 
he  buit  a  DT-600  demodulator,  by  Data 
Technolo0y  Associates,  from  scratch 
based  on  the  documentation.  He  says 
that  it  far  out-performed  any  other 
RTTY  demodulator  that  he  has  been 
able  to  construct.  Since  he  lost  Ihe 
documentation  years  ago,  and  some- 
one disposed  of  his  DT-600  when  he 
was  indisposed,  he  has  been  unable  tc 
duplicate  the  device,  if  there  are  any 
readers  out  there  with  tnformation 
about  this  denroduiator.  we  would  love 
to  hear  from  you,  as  woukJ  Enrx^ry,  I  am 
sure. 

A  brief  note  about  the  growing  col- 
lection of  RTTY  programs  available  to 
the  readers  of  this  column:  There  are 
now  five  "RTTY  Loop"  disks,  each  one 
holding  over  1  ^  Mb  of  assorted  stuff.  A 
list  ol  available  pro^^ms  is  yours  for  a 
setf-addressed,  stamped  envelope.  1 
can  E-mail  you  the  list,  as  well.  Jusl 
send  me  a  message  via  CompuServe 
(ppn  75036,2501).  Delphi  (username 
MarcWASAJR),  America  On-line  (Mar- 
CWA3AJR),  or  Internet  (f^arcWA3AJR 
@aoLcom),  The  plans  are  to  upioad 
the  coliectlons.  as  well,  to  the  Deiphi 
Radio  SIG  delaiJed  last  month. 

I've  waited  until  the  end  ol  this  col- 
umn to  tool  my  horn.  This  month 
marks  the  beginning  of  tt>e  13th  year  of 
"RTTY  Loop."  I  guess  it  can  vote  nowt  1 
can't  begin  to  tell  you  what  il  means  to 
get  the  support  I  have  been  receiving 
for  these  many  years.  I  fook  forward  to 
your  letters,  your  E-mail,  your  ques- 
tions and  your  criticisms.  I  hope  thai 
we  are  able  to  spend  more  time  togeth- 
er in  the  future,  to  explore  the  wide 
worW  of  digital  communications,  here 
in  -RTTY  Loop." 


I  Don't  miss  a  single  issue  of  73!.  Call  1-800-289-0388  to  order  your  subscription. 


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73  Amateur  Radio  Todays  July,  1994  49 


Hamsats 


Number  13  on  your  feedback  card 


Amateur  Radio  Via  Satellites 


Andy  MacAltiSter  WASZIB 
14714  Knights  Way  Drive 
Houston  TX  77083-5640 

The  Digital  Satellites 

OigitaJ  coinmunicalion  via  the  ama- 
teur-radio satellites  lias  been  around 
since  [he  early  days  of  packet-radio 
activity.  Before  ihe  first  ARRL  (Ameri- 
can Radio  Relay  League)  Amateur 
Radio  Computer  Networking  Convene 
tlon  in  1981  at  the  National  Bureau  of 
Standianjs  in  Gailtiefsburg.  Maryland, 
AM5AT  {The  Radio  Arrtateur  SateSlrte 
Corporation)  eamiarked  Special  Ser- 
vice Channel  (SSCs)  on  future  fiigh- 
orbit  satellites  for  packet  communica- 
tfons.  Dr,  Hank  Ma  gnu  ski  KA6M,  de- 
signer of  one  of  the  first  packet  digl- 
p eaters,  was  in  charge  ot  setting  stan- 
dards for  8SC  use.  This  came  at  s 
yme  when  AMSAT  was  still  recovering 
from  the  loss  of  Phase  3 A  in  1980, 
which  was  to  be  Ihe  first  high-orfail, 
long-tife  ham  sat,  Phase  3A  met  a  wa- 
lery  end  when  its  Ariane  Launcher 
Med  to  achieve  orb  it. 

Packet  operation  through  analog 
sataliiie  transponders  is  comparable  to 
direct  user'tq-user  pacl<et  procedure. 
Earty  tests  were  made  at  1200  bps 
(bits  per  second),  but  activity  at  300 
bps  using  HF  modems  was  mqre  reli- 
able, due  to  the  weak-signal  r^tuna  of 
satellite  commumcatior^s  at  the  time. 
The  use  of  the  analog  transponder 
Space  for  packet  experiments  was 
never  popular.  The  store-and-forward 
potential  of  the  AX.25  packet  protocol 
was  not  addressed  via  the  analog 
transponder  system.  A  digipeater  in 
space,  or  some  other  dlgitar  mailbox 
setup,  was  needed. 

At  the  1983  ARRL  Amateur  Radio 
Computer  Networking  Convention  In 
San  Frarx:isco.  Phil  Kam  KA9Q  pre- 
sented the  paper  "^ Modulation  and  Ac- 
cess Techniques  for  PAGSAT."  while 
Don  Connors  KD2S  presented  the 
"The  PACSAT  Project."  Don^s  paper 
described  the  design  goal  of  "total 
global  access  by  ali  hams  to  a  store- 
and' forward  packet  message  handler* 
via  satellile.  He  explained  the  need  for 
packet  satellites  and  charactenzed  the 
on -board  systems  and  technical  pa- 
rameters for  the  required  equipnrenL 

Phil's  paper  on  modulation  tech- 
niques, when  viewed  with  Don's,  laid 
down  the  blueprint  for  many  of  today's 
digital  satellites,  from  frequency  selec- 
tion to  modulation  methods.  It  was 
Shown  that  a  fonn  of  phase- shift  key* 
ing  (PSK)  would  perform  better  thtan 
standard  audio-trequency-shift  keying 
(AFSK]  on  an  FM  carrier  for  packet- 
satellite  downlinks.  AFSK-FM  has  ad- 
vantages that  include  cost,  simplicily 
and  easy  Doppler  tracking,  but  it  has 
some  tradeoffs.  These  Include  ineffi- 
cient bandwidth  usage  and  poor  noise 
performance.  Today  we  have  satellites 


that  use  both  types  of  downlink 
schemes.  All  am  in  low  earth  orbits. 

In  1984  when  UoSAT-OSCAR^II 
(built  by  the  University  of  Surrey  in 
England)  went  to  orbit,  11  canned  tt>e 
Digital  Communications  Experiment 
(DCE)  which  provides  a  proof^f-corv- 
cept  test-bed  for  PACSAT  work.  The 
experiment  acts  as  a  mailbojt  in  orttit 
to  try  various  digital  communication 
software  and  to  provide  data  on  hsrxi- 
ware  survivability,  current  consump- 
tion and  operational  behavior  in 
space.  Only  a  small  numt>er  ol  hams 
around  the  world  are  active  as  gate- 
way stations  through  the  DCE,  but 
others  can  rout©  their  messages 
to  these  gateways  for  uplinking  to 
U-0-11.  The  concept  not  only  worked 
In  19S4,  but  Is  stifi  operational  today. 
Messages  can  sometimes  be  seen  be- 
tween telemetry  frames  on  the 
145.825  MH2  downlink  at  1200  bpS, 

When  Fuji-OSCAR-12  was 
ISiJnched  in  August  1980  from  Japan, 
hams  had  their  Orst  opportunity  lo  find 
out  what  PACSATs  were  all  about. 
Whenever  the  ''J"  (2  meters  up  and  70 
cm  down)  digital  transponder  was  ac- 
tive, stations  could  access  the  mailbox 
and  ieave  messages  for  hams  next 
door  or  on  the  other  side  of  the  world. 
The  system  used  FM  for  the  uplink 
and  PSK  on  the  downlink.  Signals 
were  good  but  battery  probiems  made 
continuous  activity  impossible^  After 
only  a  day  or  two  the  system  needed 
recharging  with  corresponding  down 
periods  and  ioss  of  ail  the  messages 
in  memory.  Even  with  these  difficulties. 
the  open  digital  mailbox  was  an  excit- 
ing packet  experience.  Fujl-OSCAR- 
20  was  taunched  in  Febmary  1990  as 
a  replat^n^nt  for  F-O-12.  F-O-20  also 
has  battery  and  heat  problen^  requir- 
ing some  downiime,  but  il  is  quite  ac- 
tive today  for  those  wishing  to  use  an 
orbiting  dfgital  maiEtx>x  without  special 
software. 

in  January  1990  the  first  batch  of 
four  IWicrosats  were  launched  by  an 
Ariane  rocket  as  secondary  pay  loads. 
Tto  new  UoSATs  were  also  passen- 
gers. Sent  aloft  were  UoSAT-OSCAR- 
14,  UoSAT-OSCAR-15,  AMSAT-OS- 
CAR-16.  DOVE-OSCAR-17.  WEBER- 
SAT-OSCAR- ie  and  LUSAT-OSCAR- 
19,  Today  A-0-16  and  L-O-19  provide 
1200  bps  operation  using  FM  up  and 
PSK  down.  Specfai  PC-based,  broad- 
cast-protocol packet  software  Is  re- 
quired  to  communicate  with  these 
satellites.  W-O-iS,  sponsored  by  We- 
ber State  University  in  Ogden.  Utah, 
sends  images  in  a  special  binary  for- 
mat. D-O-17*  sponsored  by  AMSAT- 
Braiif  {BRAMSAT).  currently  transmits 
telemetry  that  can  be  heard  on 
145.825  MHz  FM.  A  standard  ama- 
teur-radio TNC  (Terminal  Node  Con- 
troller) In  conjunction  with  a  computer 
or  terminal  and  an  FM  receiver  can  be 


used  to  see  the  data  and  messages 
from  this  hamsal.  DOVE  is  also  capa- 
ble of  speech,  but  has  yet  to  fulfill  its 
potential,  due  to  minor  hardware  diffi- 
culties and  software  needs.  Work  con- 
tinues on  Dove's  recovery.  U-0-15 
died  shortly  after  launch  and.  atthough 
U-0-14  is  currently  in  commercial  ser- 
vice on  non-amateur  frequencies,  it 
provided  digital  hamsat  chasefs  their 
first  opportunity  lo  try  9600  bps  com- 
municaliorkS  with  FM  up  and  down,  us- 
ing the  broadcast  protocol. 

AMSAT-OSCAR-21  provided  the 
fliBt  operatiortal  German  RUDAK  sys- 
tem. RUDAK  is  a  complex  RISC- 
based  (Reduced  Instruction  Set  Com- 
puter) digital  transponder.  It  can  be 
programmed  to  accept  uplinks  of 
many  types  ranging  from  analog  voice 
to  high-speed  digital  <teta,  with  a  cor- 
responding wide  range  of  downlink  op* 
lions.  While  it  spends  the  largest  per- 
centage of  its  time  in  a  voice  transpon- 
der mode  with  a  downlink  of  145.987 
MHz  FM.  it  has  also  sent  packet 
telemetry,  WE  FAX  transmissions  of 
uploaded  images,  and  prerecorded 
voice  messages  A-0-2t  is  a  part  of  a 
Russian  navigalior^l  satellite  and  an- 
other amaleur-radlo  paytoad.  RS-14, 
The  voice  uplink  to  A-0«2I  is  on 
435.016  MHi 

Several  other  digital  satellites  have 
been  launched  in  recent  years. 
UoSAT-OSCAR-22  is  used  for  9600 
bps  operation  as  a  replacement  for 
U-0-14.  The  majority  of  the  traffic  on 
U'0-22  Is  terrestrial  packet  mail  for- 
warding, 

Kitsai-OSCAR-23  is  another  9600 
bps  satelElte  with  the  highest  orbit  of 
the  digital  hamsats.  This  satellite  was 
built  at  the  University  of  Surrey  in  Eng- 
iand  but  was  sponsored  by  the  Korean 
Advanced  Institute  of  Technology 
(KAIST).  Files  found  on  K-0'23  In- 
ciude  short  text  messages,  utility  soft- 
ware, picture  files,  music  (midi)  files, 
voice  mail  and  even  game  prograrris. 
If  it's  digital,  it's  probably  been  sent  via 
K-0-23.  Kitsat-OSCAR-25  is  atmost 
identical  to  K-0*23p  with  a  stlghtty  low- 
er orbit  and  more  advanced  hardware. 
Both  satellites  have  on-board  cameras 
for  earth -imaging  experiments. 

iTAMSAT-OSCAR-26  Is  another  mi- 
crosat-style  satellite.  It  was  buill  by  AM- 
SAT-ttaty.  It  currently  uses  1200  bps 
with  FM  up  and  PSK  down  with  the 
broadcast  protocd.  It  can  also  operate 
at  higher  data  rat^  when  appropriate 
software  is  checked  out-  1-0-26  is  fully 
capable  of  the  popular  FM-up^FM-down 
9600  bps  format  of  the  UoSATs  and 
Kitsats,  In  addition,  a  telemetry  decod- 
ing program  known  as  TLMDCITA  Js 
available  from  AMSAT-ltaly. 

AMRAD-OSCAR-27  was  built  by 
Interferomethcs  and  the  Amateur  Ra- 
dio Research  and  Development  Co. 
(AMR AD  of  McLean,  Virginia)  in  th© 
Washington,  DC,  area,  it  is  piimarily  a 
commercial  microsat  with  amateur-ra- 
dio capabilities.  Most  daytime  opera- 
tion is  ham-related  as  a  single-channel 
FM  voice  transponder  with  a  145.850 
MHz  uplink  and  43aS00  MHz  down- 
link. It  is  capable  of  high-speed  data 


operation  experiments  and  is  used  on 
non -amateur  trequencies  as  EYES  AT 
to  demonstrate  the  usefulness  of 
store -and-iorward  commerciat  com- 
munications with  low-orbit  satellites.  A 
telemetry  decoder  program  Is  avail- 
able from  the  AMRAD  BBS  at  (703) 
734-1387  or  via  anonymous  ftp 
throtigh  the  Internet  at  ftpJunet.fi  or 
ftp.digex.neL 

POSAT  st^ 8 times  called  POSAT- 
OSCAR-23.  is  a  UoSAT-based  satet- 
lite  from  Portugal.  Like  A-0-27*  il  has 
commercial  uses  and  shares  Its  time 
in  orbit  between  ham  and  industry-re- 
lated activities.  It  has  been  operational 
on  ham  frequencies  at  9600  bps. 

Finding  lUore  Information  on 
DIgi-Sats 

The  unique  types  of  digitaJ  hamsats 
in  orbit  reciuim  different  hardware  and 
software.  It  is  Iseyond  the  scope  of  this 
introduction  to  detail  all  the  require- 
ments. Fortunately,  there  are  several 
sources  of  information  on  how  lo  get 
active  via  these  satellites.  AMSAT-NA 
has  several  books  and  software  pro- 
grams to  provide  advice  on  how  to  be- 
gin. The  Satetlite  Experimenter's 
Handbook  by  Martin  DavkJoff  K2UBC 
is  published  by  the  ARRL  and  pro- 
vides good  general  information  on 
satellites  with  specifics  covering  the 
amateur-radio  satellites  and  packet 
satellites.  Decoding  Telemetry  from 
the  Amateur  Sateflites  by  G.  Gould 
Smith  WA4SX1VI  gives  in-depth  cover- 
age  of  telemetry  systems  on  the  ama- 
teur satellites,  with  empriasis  on  the 
digital  hamsats.  The  Pacsat  Begin- 
ner*s  Guide  explains  the  methods  of 
commonicaling  with  packet  satellites 
ar>d  indiides  a  disk  containing  the  PC 
software  for  the  broadcast  protocol 
"Getting  Started  in  Amatetjr  Satellites" 
Is  a  VHS  video  tape  from  CO  Commu- 
nications that  covers  all  modes  of 
satellite  operation  and  Includes 
demonstrations  of  the  broadcast  pro- 
tocol  via  digital  satellites.  Tracking 
software  is  also  available  from  AMSAT 
for  most  types  of  computers. 

Many  articles  in  OS7;  CO,  T$  Ama- 
teur Radio  Today,  Woridradio.  QBX, 
OSCAR  News  (AMSATUK)  and  The 
AMSAT  Journal  (AN/ISAT-NA)  have 
been  written  over  the  last  lO  years 
describing  past,  present  and  future 
amateur- radio  digital  sateliites.  The 
January /February  1994  issue  of  TTre 
AMSAT  Joumat  contained  a  complete 
AMSAT  Journat  index  compiled  by 
WA4SXM.  Over  20  articles  atx>ut  digi- 
tal satellites  in  a  four-year  period  are 
noted.  The  "Hamsats"  column  fn  73 
Amateur  Radio  Today  has  featured 
digital  satellite  updates  several  times. 
Mote  Table  1  for  a  current  list. 

Getting  Started 

There  are  several  easy  ways  10  get 

started  with  the  digital  satellites.  If  you 
have  a  Bell  202  style  modem  and  can 
modify  it  for  mark  and  space  bit  inver- 
sion, you  can  monitor  U-0-11  on 
145,825  MHz  FM.  The  satellite  sends 
ASCII  data  at  1200  bps.  The  continu- 
ous data  and  messages  can  be  easily 


50  73  AmalBUf  Radio  Today  *  July,  1 994 


Issue  Date 

Rage 

May  1990 

46 

June  1990 

51 

December  1990 

81 

September1991 

54 

October  I99t 

62 

December  1991 

62 

Apiil  1992 

76 

July  1992 

&3 

November  1992 

56 

April  1993 

57 

June  1993 

56 

July  1993 

64 

Novenritffir  1 993 

53 

December  1 993 

50 

hiav1994 

60 

Topic  Covered 

Microsal  and  F-O-20  Enformation 

Modems  and  Hamsat  operation 

Packet  via  satelfite 

WEBER  SAT  ground-ststlon  operalion 

UoSAT'OSCAR-22  taunch 

9600  bps  modems  and  how  lo  use  them 

Piclure  files  on  the  digi-sals 

Kftsat-OSCAR-23  pre-launch  data 

K-O-23  posHaunch  information 

Operating  through  K-O-23 

Pre-iaunch  data  on  K-O-25 

How  to  work  SAREX 

P relaunch  data  on  OSCARs  25-28 

Post-launch  data  on  OSCARs  2S-28 

The  fBtum  of  Dove-OSCAR-17 


Tabte  h  Digi-sat  '^Hamsats' coiumns  in  73  Anrateyf  Radio  Today* 


received,  and  even  captured  for  later 
study  using  a  computer  in  conjur*ction 
with  communications  software  that 
can  work  with  the  modem. 

D'O-irs  standard  AX.25  packet 
downlink  is  also  on  145.655  MHz  FM, 
Power  tevels  ttom  the  satellite  are  typ- 
ically 10  times  stronger  than  U-O-n 
and  can  be  heard  on  almost  any  an* 
tenna.  Anyone  who  is  currently  active 
on  VHP  packet  can  hear  the  signals 
and  see  the  resulting  telemeUy  and 
messages  on  a  CRT  or  other  display 
device.  For  those  who  can  capture  the 
data  to  disk,  programs  are  available  lo 
decode  the  data  and  display  informa- 
tion on  the  satellite's  activities  and 
health.  One  program  available  from 
AMSAT-NA  for  $20  is  TLMDC-ll,  All  of 
the  data  channels  can  be  decoded 
and  GKamined  with  this  program, 

The  Russian  M/r  Space  station  has 
a  paclf^et  BBS  (Bulletin  Board  System) 
on  145.55  MHz.  Like  DOVE,  the 
downlink  Is  AFSK  FM  and  is  compati- 
ble with  a  standard  TNC.  but  is  fully  in- 
teractive like  a  terrestrial  packet  BBS. 

When  the  space  shuttle  lai<es 
SAREX  (Shullle  Amateur  Radio  Ex- 
periment) lo  orbit,  one  mode  of  opera- 
tion is  the  paci<el  ROBOT  The  ckjwn- 
link  is  145-55  MHz,  but  unlike  Mir.  the 
LTpNnk  is  different.  Earthbound  stations 
musi  transmit  on  144,49  MHz  to  con* 
necl  to  the  SAREX  TNC, 


lbi)le  2  is  a  Tist  of  the  digital -ready 
hamsats-  The  list  is  not  complete,  but 
Shows  the  phncipaE  actrvity  of  each 
satellite  and  typical  frequencies  of  op- 
eration. For  1200  bps  FM^SK  opera- 
tion, a  special  modem  is  needed  in  ad- 
dition to  the  usual  TNC.  conputer.  ra- 
dios and  software.  These  PSK 
modems  are  available  from  Tucson 
Amateur  Packet  Radio  Society  (mo- 
dem kit),  PacComm  (add-on  modem), 
L  L.  Grace  Commtinlcations  Products 
(DSP  umXj  and  others.  For  9600  bps 
activity,  a  htgh-speed  modem  is  re- 
quired, along  with  some  modiftcattons 
to  the  TNC,  transmitter  and  receiver. 
High-speed  modems  and  complete 
9600'bps  TNCs  are  also  availabEe 
from  TAPR  (kit),  PacComm  (add-on 
modem),  Kantronics,  AEA  (DSP  unit) 
and  L  L  Grace  (DSP  unit).  Some  de- 
vices, fike  the  DRSI  DPK-9600  TNC, 
are  much  more  rijfficuEt  to  properly  In- 
terface tor  satellite  work,  due  to  their 
emphasis  on  ten^estrial-style  hardware 
compatibiJity. 

The  Future 

More  digitai  hamsats  are  on  the 
way.  Some  are  based  on  the  microsat 
bus,  like  UNAMSAT  from  Mexico, 
while  others  are  being  designed 
around  the  UoSAT  structure.  Data 
rates  are  e)tpected  to  increase  to  38.4 
kbps  and  beyond,  and  higher  frequen- 


S&tellite 

Uplinks 

Downlinks 

Current  Activity  and  Noti?s 

U-0-11 

145.825 
435,025 
2401 .500 

1200  bps  ASCII  (Bell  202) 

U'0'1 4 

9600  bps  commercial  service 

A<M6 

145.900 

437.051 

1200  bps  FSK/PSK-PB" 

145.920 

437,026 

PB  call  =  PACSAT-11 

145,940 

2401.143 

PG  call  =  PACSAT-12 

145.960 

D-(M7 

145.625 

2401 .220 

1200  bps  FSK  AXJ25  data 

wate 

437,075 
437.100 

1200  bps  PSK  binary  data  &  pix 

L-o-ig 

145.840 

437.150 

1200  bps  FSK/PSK  TB" 

145.860 

437.125 

PBcal  =  aJSAT-11 

145.880 

PGcalULUSAT-12 

145.900 

F-O-20 

145.850 

435.910 

1200  bps  FSKyPSK  AX25  B85 

145.890 

145.910 

A-azi 

435,016 

145,983 

FM  Vckae  transpofxter  (se©  text) 

U-a-22 

145.900 

435,120 

9600  bps  FSK  -PB- 

145.975 

PBnalUUOSAT5-11 
PGcaH  =  LIOSAT5-12 

K-O-23 

145.650 

435.175 

9600  bps  FSK  -Pe- 

145.900 

PBcafl  =  HL0M1 
PGcall  =  HL01-l2 

K-O-25 

145.670 

436.500 

9600  bps  FSK  "PB" 

145,980 

435.175 

PBaaB-HLQ2-11 
PGcall  =  HL02-l2 

I-0-26 

145.875 

435.867 

1200  bps  FSK/PSK  T8" 

145,900 

435.8^ 

PBcaU=lTMSAT-11 

145,925 

PG  calU  rrMSAT-12 

145.950 

A-O-27 

145,850 

436.800 

FM  Voice  transponder  (see  teirt) 

P^-28 

145.925 

435^50 

9600  bps  FSK  "PB" 

145.975 

435^75 

PBcalUPOSATMl 
PG  call  =  POSAT  1 2 

MfH 

145.550 

145.550 

1 200  bps  AX.25  BBS 

SAREX                144,490 

145.550 

1200  bps  AX.2S  ROBOT 

Tabte  2,  The  Digital  Hamsats' 
(MHz)  are  sttown  first  All  upHnk 


current  activity.  Primary  downlink  frsquenctBS 
frequencies  Bfe  sitnuftansousiy  active. 


cies  will  be  more  common.  Digital 
compression  techniques  and  im- 
mense sateliite  on-board  memories 
will  allow  larger  files  and  even  dig- 
ital full-motion  video  experiments, 
PACSAT  was  only  an  Idea  in  the  early 
1980s.  Today  it  has  many  forms 
and  has  become  the  dominant  3ow- 
earth-orblt  hamsal  Commercial  and 


government  interest  in  small  digital- 
ready  satellites  has  expanded  dram  at* 
ically  since  the  launch  of  tho  mi- 
crosats  in  early  1990.  This  has 
caused  competition  for  'leftover" 
space  on  launchers^  but  can  also  be 
seen  as  recognition  for  a  pioneering 
effort  that  was  begun  in  the  amateur^ 
radio  community. 


Handheld  Repeater  Controller 


SiMClnjm  Eledranic  P/oduc^ 
frititxlijces  ttie  wofhi's  first 
handield  repeater  controllef . 
Ha  brgef  tttan  most  handhekj 
lacboa,  the  HRC-10  converts 
a  single  or  duaf-baixl  radio 
km  a  f^  teatured  simpler:  or 
tb^itex  repealer  system  Key 
tealureis  of  the  HRC-10  in- 


duce voce  I  Der.  DTMF  Co^ 
trol  and  progTammifTg.  hang 
and  time-out  tamers.  Digital 
Voice  Operated  Squelch 
(DVOS^),  telemetry  tones, 
and  ^rwme  voce  marl  ^ot 
Phone  4QB^3a-Z7ea 
FAX  408-436-«027 

S29d 


Say  You  Saw  It  In 

73  Amateur  Radio  Today 


hambrew 


FOR  AMATEUR  RADIO  DESIGNERS 
AND  BUILDERS    Q„^teriy 

«20/yr. 


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AcHnnced 

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CIRCLE  es  ON  PEAOEft  SERVICE  CARD 


CIRCLE  2BB  ON  HEADER  3£I^VICE  CARO 


73  Amateur  Radio  Today  July,  1994  51 


^^  Numoer  14  on  yoi 

Carr's  corner 


Number  14  on  your  Feedback  card 


Joseph  J.  Carr  K41PV 
RO,  Box  1099 

Fsils  Church,  VA  22041 

Dumping  AM  BCB 
Interference 

The  AlVl  broadcast  band  (AM  BCB) 
funs  from  540  kHz  to  1700  kHz.  (You 
fead  right:  The  FCC  raised  the  upper 
limit  ffom  1600  to  1700  kHz  not  long 
ago.)  Most  stations  are  local,  and  rela- 
tively low-power.  A  few  stations  are 
farge  regionals  or  clear-channe!  50,000 
watt  blowtorches.  Because  AM  BCB 
stations  are  largely  focal  thers  are  lots 
of  them,  so  it's  a  pretty  safe  bet  that 
many,  perliaps  most,  ham  operators 
are  close  to  al  least  one  station.  When  I 
was  a  recent  graduate  from  Movice 
ranks,  a  friend  of  mjne,  the  late  Johnnie 
H,  Thorne  K4NFU.  lived  across  the 
street  from  WARL  in  Arlington,  Virginia. 
The  station  operated  with  1,000  watts 
on  780  kHz.  TTie  fifth  harmonic  of  780 
kHz  landed  right  in  the  middle  of  the  75 
meter  phone  bar^d.  So  what? 

If  you  are  any  distance  at  all  from  an 
AM  BCB,  there  is  practically  zero 
chance  that  a  fifth  harmonic  will  be 
found.  Right?  Afier  aH.  AM  BCB  sta- 
tions are  regulated  a  lot  heavier  than 
ham  stations.  While  we  need  to  keep 
our  harmonics  -40  dB  down  from  the 
carrier,  AM  BCB  stations  are  typically 
-60  d8  down,  or  more.  One  AM  BCB 
engineer  showed  me  spectrum  analy^- 
er  reports  from  a  consulting  engineering 


firm  that  showed  the  second  harmonic 
down  -85  dB  from  the  carrier,  and  the 
higher  order  harmonics  even  lower.  So 
what's  the  big  deal? 

Weil,  it  seems  that  any  time  a  strong 
RF  signal  of  any  frequency  is  present  at 
the  input  of  a  radio  receiver,  it  is  possi- 
ble for  the  signal  to  bust  through  what- 
ever front-end  tuning  or  bandpass  filter- 
ing exists  to  overbias  the  input  device 
(transistor,  IC,  lube),  and  cause  it  to  go 
nonlinear.  In  this  condition,  a  harmonic- 
free  signal  from  the  AM  BCB  station  will 
generate  harmonics  in  the  receiver. 
K4MFU's  station  receiver  at  the  time 
was  a  late  1950s  vintage  Ham  marl  und 
HQ-110  which,  by  all  reports,  was  at 
least  a  decent  receiver,  if  not  spectacu- 
larly so.  But  when  the  receiver  was  lo- 
cated only  100  yards  from  the  WARL 
antenna,  it  overloaded  and  produced 
harmonics  well  past  the  40  meter  band* 
The  solution  to  the  problem  is  to  put  ei- 
ther an  AM  BCB  high-pass  filter  in  line 
with  the  antenna,  or  to  put  a  specific 
frequency  paratlel  resonant  wavetrap 
(tuned  to  the  offending  station's  fre- 
.quency}  in  line  with  the  signal  line.  Al- 
ternatively, a  series-resonant  trap 
across  the  signal  line  could  be  used.  In 
either  case,  the  offending  signal  is  at- 
tenuated seriousEy 

AM  BCB  Wavetraps 

Two  simple  wavetraps  are  shown  in 
Figure  1,  while  a  'universal"  printed  Cir- 
cuit board  for  these  circuits  is  found  in 


rem 


LI 

220  ^H 


C1 

365   pF 


(a) 


frr^rfi/i/v\viMiVM-^yy;^^j^^ 


J1 

ANT 


e 


LI 

220  ^H 


C1 
365  pF 


(b) 


Figure  1.  A)  ParaHef-funed  wavetrap,  B)  Senes-tuned  wavetrap. 


Figure  2,  (These  Universal  Wavetrap 
boards  are  available  for  $4  plus  $1.50 
S  &  H  per  order  from  FAR  Circuits, 
1SN640  Reld  Court,  Dundee  IL  60118.) 
The  circuit  in  Figure  1A  is  parallel  re  so- 
nants so  is  placed  in  series  with  the  sig- 


JUMPERS  FOR  SERIES  RESONANT  TRAP 


INPUT 


^ 


Ji 


U^n^JOiiSflt    iJRUETRfHf^ 


JU2  j2  _ 


m 
o 


o 
o 


o 


OUTPUT 


JUMPERS  FOR  PARALLEL  RESONANT  TRAP 

I  mi  I^IIMIfflBMBM^^^^^^^  ,1,]       ii,a,li,i» 


INPU 


JU3 


J2 


^.r- 


^ 


9 


OUTPUT 


Figure  2.  A)  Printed  circuit  layout  for  Universa!  Wavetrap:  B)  jumpers  for  series  fBSomnt  trap;  C)  jumpers  for  parallel  resonant  top. 
52  73  Amateur  Radio  Today*  July,  1994 


nal  line  between  Input  (Jl)  and  output 
(J2).  This  is  done  because  a  parallel 
resonant  circuit  has  a  high  impedance 
to  its  resonant  frequency,  and  a  low 
fmpedance  to  all  frequencies  removed 
from  the  resonant  frequency  by  more 
than  a  little  bit.  Thus,  your  HF  ham  band 
signal  will  pass  through  with  little  attenu- 
ation, while  the  offending  AM  BCB  sig- 
nal is  blocked. 

The  version  in  Figure  1 B  is  series 
resonant,  so  It  is  placed  En  parallel  with 
the  signal  line.  Series  resonant  signals 
have  a  low  impedance  to  the  resonant 
frequency,  and  a  htgh  impedance  to  fre- 
quencies removed  from  resonance. 

In  both  cases,  we  use  a  220  uH  sfug- 
tuned  coil  and  a  14-365  pF  variable  ca- 
pacitor. The  capacitor  can  be  a  standard 
single-section  "broadcast  variable." 
These  capacitors  are  a  little  hard  to  find 
In  the  USA  (although  not  in  England), 
but  Ocean  State  Electronics  [POB  1458, 
6  Industrial  Drive,  Westerly  Rl  02891; 
(401)  596-3080  (voice),  (401)  596-3590 
(FAX)  or  (800)  866-6626  (orders  Only)] 
has  several  offerings  In  their  catalog. 
Order  No.  BC-14400;  it  is  a  14-365  pF 
model. 

The  printed  circuit  board  can  be  used 
either  with  the  off-board  broadcast  vari- 
able capacitor  or  with  a  trimmer  capaci- 
tor and  as  many  disk  ceramic  capacitors 
as  needed  to  achieve  the  required  ca- 
pacitance. If  you  elect  to  use  on-board 
capacitors,  tfien  r^ote  that  CI  A  Is  a  trim- 
mer capacitor,  while  C1 B,  C1C  and  C1 D 
are  as  many  fixed  disk  ceramic  capaci- 
tors as  are  needed  to  make  the  correct 
capacitance.  The  capacitors  selected 
are  the  SG -series  from  Dig i -Key  (POB 
677,  Thief  River  Falls  MN  56701*0677; 
{800}  344-4539).  The  SG-3014  Es  a  10- 
180  pF  trimmer  in  most  cases,  not  all 
capacitor  slots  on  the  board  will  be 
needed. 

The  inductor  on  the  printed  circuit 
board  coufd  be  a  toroid  inductor,  al- 


CI 
1590    pF* 


w 


C2 
950    pF*^ 


C3 


w 


15&0   pF*         ^ 


J2 
RCVR 


I  l-ra  I  f  an  ■  I  q  |  .i-^^h  l-«-l -I  l->^l->4^H^1 


*    2  -  560  pF  +  1  -    470  pF 


t  -  680  pF  +  1  ^  270  pF 


RgurB  3.  Highi>B$s  UltBr  (1,900  kHz)  for  AM  BCB  sappressfon. 


thougti  the  number  of  turns  may  prove 
excessive  (or  sorne  of  g$  to  wind.  The 
particular  pattern,  riowtver,  Is  for  a 
Toko-brand  slug-tuned  coif.  In  the  Digi- 
Key  catalog,  these  are  the  10  mm  size 
coils  (e.g.  10EZ.  10EZC.  lOEZH.  etc.). 
For  example  a  Digi-Key  cat.  no.  TK- 
1223  Is  a  220  jjH  type  lOEZ  coiL 

High-Pass  Filter  Approach 

The  alternate  approach  is  to  use  a 
high-pass  filter  between  the  antenna 
and  the  receiver  antenna  terminals,  The 
filter  should  bB  as  close  as  possible  lo 
the  receiver  antenna  terminals.  In  a 
transceiver,  ttie  filter  may  tiav^  (o  b%  in- 
side the  rig's  case  unless,  you  have  one 
that  pencils  a  separate  receive  anten- 
The cfrcuil  for  the  basic  filter  Is 
shown  In  Figure  3;  the  printed  circuit 
board  in  Figure  4,  The  capacitor  slots 
on  the  printed  circuil  board  are  de- 
signed for  a  variety  of  different  types  of 
capacitor:  disk  ceramic,  silver  mica, 
polyethylene,  and  other  forms.  Thaf s 
why  there  are  four  sets  of  holes  each 
for  01 «  C2  and  C3.  In  most  cases,  you 
will  have  lo  mix  and  match  the  capaci- 
tors lo  make  the  desired  values.  The 
.1S90  pF  capacitors  (Cl  and  03)  are 
made  from  two  560  pF  ar>d  one  470  pF 
capacitor:  C3  {950  pF)  Is  made  from 
one  680  pF  and  one  270  pF  capacitor. 
The  inductors  could  easily  be  loroid 


inductors.  A  T-37'15  (REO/WKT)  tofo*d 
requires  about  19  turns  of  enameled 
wire  to  maKe  the  required  Induclance, 
As  before,  however,  the  printed  circuit 
holes  are  designed  for  a  shielded  Toko 
coil  (e.g.  Digi-Key  TK-1414).  Builders 
can  buy  the  Universal  High-Pass  Re- 
ceiver Filler  boards  for  $4.50  plus  SI  .50 
S  &  H  per  order  from  FAR  Circuits  (see 
address  above). 

The  components  for  the  filter  in  Fig- 
ure 3  are  iniended  for  a  cutoff  fraquen' 
cy  of  about  1.9  MHz,  which  means  that 
signals  tn  the  AM  BOB  are  attenuated, 
hlowevef,  Itie  printed  circuit  t>oard  and 
basic  design  can  be  used  for  any  cutoff 
frequency  desired  fnom  VLF  to  VHF. 
Just  caJcutate  the  values  (or  the  fre- 


quency you  want  to  use  as  a  cutoff. 

The  component  values  for  tfie  filter 
were  calculated  using  the  "ANTLERS 
for  Windows"  software.  This  software 
podcage  is  designed  to  caknjiate  anten- 
na lengths,  but  has  a  Tuning  Ctrcuils" 
function  in  which  one  of  the  menu  items 
Is  "Filters."  Both  high-pass  and  low- 
pass  cases  are  covered.  "Al^m-ERS" 
(sn  be  used  to  calculate  the  values  for 
filters  up  to  30  MHz,  in  case  you  want 
to  make  one  other  than  1 .9  MHz. 

"ANTLERS  for  Windows"  Software 

"ANTLERS"  has  the  following  func- 
tions: HF  antennas  (3^30  MHz),  VLF- 
MW  loop  antennas  (1 0-7,500  kHz),  low 
frequency  antennas  (500-7,500  khz). 
VHFAJHF  antennas  (30-2.000  MHz), 
and  Tuning  Networks  (10  kHz-30 
MHz), 

Antennas  covered  In  the  HF  functkxi 
include:  half-wavelength  standard 
dipole,  folded  dipole.  inverted-vee 
dipofe,  G5RV.  off^center-fed  doublet 
{OCFO),  Windom.  double-extended 
Zepp,  Franklin  array,  Lazy-H,  one- 
wavefength  loop,  half^defta  loop,  two* 
wavelength  bi^square  loop,  quarter 
wavelength  verticals,  haif-wavelength 
verticals,  five -eighth  wavelength  verti- 
cals, three-element  yagl  beam,  two-eie- 
ment  quad^  phased  vertical  array,  bob- 
tail curtain,  and  Thome  array.  The 
lengths  of  the  elements  and  any  match- 
ing sections  are  included. 

In  Hie  loop  antenna  !ufK:tlon,  the  pro- 
gram calculates  inductance  of  a  loop  oi 
*A"  side  lenglh  and  "B"  depth,  as  well 
as  the  capacitance  needed  to  resonate 
the  loop  to  a  specific  frequency. 
Square,  triangle,  octagonal  and  hexag- 


onal loop  shapes  are  covered. 

The  low-frequency  antennas  func- 
fion  works  lo  7,500  kHz,  so  it  Is  useful 
to  hams  on  160m,  75.'80m  and  40m.  It 
includes  the  simple  dipole.  the  indue- 
tn/ely-ioaded  dipoEe  {two  cases:  induc- 
tofs  at  the  feed  point  arid  inductors  in 
the  center  of  each  element),  the  twin- 
lead  tee  antenna  (TLTA),  and  the  kiad- 
ed  discone  (or  "dippy  discone,"  as 
some  call  ft). 

In  the  VHF/UHF  function,  the  pro- 
gram calculates  the  element  lengths 
and  matching  section  lengths  (tf  used) 
for  all  three  dipoles  also  used  in  tine  HF 
region  (see  alxive),  quarter  wavelength 
verticals.  5/8  wavelength  verticals, 
three -element  and  six -element  yagis. 
and  Iwo-element  and  three -element 
quads. 

In  the  tLining  networks  function, 
"ANTLERS  for  Windows"  calculates  the 
numt>er  of  turns  needed  to  achieve  a 
desired  inductance  on  a  toroid  coil 
form,  the  resonance  of  an  LC  circuit 
(when  C  is  known  or  when  L  is  known), 
arKJ  filtefs  (LPF  and  HPF  cases).  It  will 
also  calculate  the  component  values  for 
antenna  tuning  units,  or  impedance 
matching  networks  If  you  prefer,  such 
as  inverted-L  section,  L-seclion,  re- 
verse-L  section,  pi-network  and  the 
split-capacitor  networl<. 

in  all  cases,  information  Is  available 
for  the  specific  type  of  antenna  being 
calculated.  The  program  uses  scroll 
bars  to  input  data  such  as  frequency,  in- 
ductance^ and  so  forth  (as  needed). 

"AfsnXERS  for  Windows  2.00'  i^n 
tje  obtained  from  me  for  $30  poslpald 
at  P.O,  Box  1099,  Falls  Church  VA 
22041. 


Rgure  4.  Pmtedawuit  txyard  for  Universai  High-Pass  Receive  Fitter. 


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73  Amateur  Radio  Today  *  July,  1 994  53 


Humber  1 5  on  your  Feedback  card 


V  s  nurnoer  t  a  on  your  reei^ 

Hams  with  class 


Caroie  Perry  WB2fAGF 

MB(Mb  Mentors,  inc. 

P.O.  Box  131646 

StBten  island  NY  10313<HXf6 

Upl  Up!  And  Awayl 

When  the  Invitation  first  arrived  to 
attend  the  launch  of  the  space  shuttle 
Endeavour's  mission  STS-59,  I  was, 
of  course,  ecstatic  for  the  entire  first 
weeic  of  April.  There  are  few  things  in 
life  that  are  quite  so  exciting  as  watch- 
ing th€  122-foot'bng  ort>lter  lift  off  liKe 
a  rocket,  orb^  like  a  spacecraft  and  re- 
turn to  earth  Oft  a  landing  strip  like  a 
glider. 

This  invitation  from  Mlssiori  Spe- 
ctafist  Jay  Apt  NSQWL  was  especially 
exciting  because  I  was  atife  to  t>hng 
guests  with  me.  After  my  own  two  chil- 
dren nose-dived  across  the  room  at 
me  for  the  invitations.  I  decided  to 
make  this  into  an  incredible  opportuni- 
ty for  some  lucky  student  in  my  ham 
radio  program, 

I  ran  a  contest  for  my  slxth-^  sev- 
enth- and  eighth-graders.  They  were 
asked  to  write  an  essay,  describing 
why  they  should  be  chosen  to  attend 
the  launch.  Hundreds  of  children  put 
their  feelings  about  the  Space  Pro- 
gram  down  on  paper.  They  were  ali 
wonderfuL  ft  was  great  to  see  such 
enthusiasm.  Usually,  when  someone 
mentions  thai  they've  visited  a  special 
piace  near  Oftando.  the  other  kids  as- 
sume il  must  have  been  Disney  World. 

One  of  my  eighth-grade  young 
ladies.  Ren^e  Hoehn  KB2QMR,  was 
chosen  lo  go,  Renee  participated  Jn 
last  year's  Ocean  Challenge  and  has 
spoken  to  several  of  the  astronauts  on 
the  CQ  All  Schools  Net  during  the  past 
two  years.  She  has  expressed  a  keen 
interest  in  all  the  space  projects  i  do 
with  the  chiEdren.  Ren^e  is  considering 
becoming  an  astronaut. 

Both  Renee  and  her  mother  Ellen 
were  in  constant  touch  with  me  as  the 
big  day  grew  near  The  entips  school 
got  involved  with  our  trip.  Children 


who  arnnl  even  in  my  program  were 
stopping  by  to  ask  questk>ns  atxjyt  the 
Endeavour's  mission.  So  much  inter- 
est and  enthusiasm  was  generated 
that  3!  really  became  a  school "^wide 
event.  Long  computer  banners  were 
hung  In  the  hallways,  wishing  us  a 
good  trip.  Ren^e  became  somewhat 
of  a  local  celebrity,  and  her  eagerness 
was  contagious.  She  was  only  too 
happy  to  share  her  expectations  with 
the  ham  radio  operators  she  spoke 
with  on  our  school  radio  station. 

The  Launch 

On  April  6th  we  left  for  Ftorida  with 
the  best  wishes  ol  the  student  body 
and  staff  of  Intenmediaie  School  72  in 
Staien  Island,  NY.  Everyone  really 
seemed  to  be  proud  that  two  repre- 
sentatives of  our  school  would  be 
there  in  person  to  witness  this  Spec- 
tacular event. 

The  Endeavour  had  its  share  of 
setbacks  getting  launched.  On  Friday, 
April  Q,  we  were  up  at  3:30  a.m.  lo  en- 
joy breakfast  together  and  to  get  over 
to  the  Kennedy  Space  Center  to  see 
the  sun  come  up  over  the  shuttle  on 
the  launch  pad.  It  was  positively  awe- 
inspirir^g. 

It  was  so  incredible  to  be  part  of  the 
group  of  onlookers  wfth  cameras  and 
binoculars  poised  and  ready  for  the 
big  moment.  There  was  definitely 
something  sun^eallstk;  atxjul  the  eaity- 
moming  scene.  We  even  gol  to  meet 
some  media  people  from  Germany 
that  day  who  were  making  a  docu* 
mentary  movie.  NASA  and  the  space 
agencies  of  Italy  and  Germany  provid- 
ed the  $3S6  million  mdar  equipment 
aboard  Endeavour. 

The  sky,  however  was  definitely 
overcast  that  day.  "Everything  in  every 
direction  .  .  Js  solid  overcast."  Robert 
Hoot''  Gibson  reported  from  a  weath- 
er airplane  more  than  an  hour  after 
Endeavour  was  to  have  taken  off.  The 
doitds  parled  slightly  later,  but  as  they 
did.  dangerous  winds  Kicked  up 
across  a  nearby  runway  where  the 


Pholo  A.  Left  to  right:  Renee  KB20MR,  Mrs.  Hoehn,  CaroiQ  WB2MGR  and  LOri 
KA2TCC  (Caroie's  daughter),  early  in  the  mommg  at  the  taunch  site. 


shuttle  would  try  to  land  In  case  of  an 
emergency  shortly  after  liftoff,  ""It 
would  appear  weVe  traded  one  va- 
gary for  another,"  launch  commentator 
George  Dltler  said  at  the  Kennedy 
Space  Center, 

We  listened  carefully  to  the  live 
broadcasts  over  the  speaker  system 
at  Ihe  viewing  site.  They  spoke  about 
the  t^ckgmunds  of  the  six  astronauts 
on  ticard.  We  listened  especially  at- 
tentivety  to  tf>e  plug  for  amateur  radio 
when  they  Spoke  about  Dr,  Jay  Apt 
N5QWL  and  Dr.  Linda  Godwin 
N5HAX,  Jay  is  the  Mission  Specialist, 
He  is  the  Commander  of  ttie  Blue  Shift 
and  will  operate  the  shuttle  systems 
during  the  "night"  shift,  while  Linda. 
who  is  the  Pay  load  Commander,  Is  re- 
sponsible for  overall  operation  of  three 
large  radars  in  the  shuttle's  cargo  day 
during  the  "day"  Shift, 

The  secondary  payload  is  Shuttle 
Amateur  Radio  Experiment,  or 
SAREX.  Nine  different  schools  have 
been  selected  to  partidpaie  in  SAREX 
forttirs  mission. 

Saturday  nroming,  Apnl  S,  at  7:05. 


all  conditions  were  perfect  for  liftoff. 
Rente's  mom  said  that  the  shuttle 
seemed  to  "glow  magnificently  as  it 
lifted  off  into  the  sunrise.  As  the  final 
rocket  boosters  separated  and  fell  into 
the  water,  they  looked  like  falling 
stars,"  For  days  afterwards  both 
Ren^e  and  her  mother  said  that  view* 
ing  the  liftoff  ol  Ihe  Endeavour  was 
Ihe  experience  of  a  lifetime/ 

When  we  returr»ed  to  school  every* 
one  was  eager  to  hear  about  wtiat  we 
had  seen.  I  commandeered  Renee  to 
speak  to  several  of  my  ham  radio 
dasses^  l  smiled  to  myself  as  she  de- 
scribed the  sounds  and  feelings  of  the 
moment  of  liftoff.  All  the  children  want- 
ed  lo  know  what  it  sounded  like. 
Renee  described  11  as  being  tike  "mil- 
lions of  firecrackers  going  off  at  the 
same  time." 

One  of  the  many  nice  things  about 
being  a  teacher  at  a  time  like  this  is 
that  an  incredible,  out  ol  the  ordinary, 
experience  such  as  witnessing  a  shut* 
tie  launch  can  be  Shared  wilh  so  imny 
children.  It  adds  a  new  meaning  to 
"show  and  tell.* 


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54  73  Amateur  Radio  Today  •  July,  1 994 


Humber  16  on  your  Feedback  card 


MiClwef  Brym  WB8VGE 
2225  MayfhwBf  NW 
M^ssHion  OH  44646 

More  Modifications 

If  the  DX  is  not  running  and  the 
bands  seenn  dead,  what  do  you  do? 
Well,  you  could  do  Wke  Scott  NSJSK 
does  and  raise  aphlds.  or  you  couJd 
heat  yp  the  soldering  ifon  and  make 
same  modHicaiions  to  your  equipment. 

Ttiis  monlh  Tve  got  several  m<xjifi- 
cations  for  you.  The  first  deals  with  the 
very  popular  MFJ  QRP  rigs. 

mj  QRP  Rigs 

The  first  production  run  of  these 
nifty  fittle  rigs  suffered  from  low  audio 
gain.  The  poky  LM3S&  audio  power 
amplifier  was  again  pressed  into  use. 
In  the  MFJ  9020,  the  LM386  is  sup- 
plied wrth  its  operating  voltage  from 
the  rig's  main  voltage  regulator.  In  the 
case  of  the  9020,  ihe  regufator  is  an 
LM317.  The  output  of  the  regulator  is 
Sdi  for  10,5  volts.  This  is  the  voltage 
the  rig  runs  on,  with  the  exception  of 
Ihe  final  RF  output  transistor.  Since 
the  audio  amplifier  is  also  tieing  pow- 
ered by  the  10.5  volt  VCC,  fts  output 
runs  lower  than  usual  The  fix  is  sim- 
ple. All  you  have  to  do  is  rewire  the 


Low  Power  Operation 


VCC  run  so  the  L^366  ts  supplied  by 
Itie  unregulated  side  of  the  LM317. 
The  e>ctra  2  volts  or  so  really  ma*c^ 
an  improveffient  in  gain. 

Don't  try  to  adjtjst  the  LM317  for  a 
higher  output — you'JI  screw  up  some 
of  the  other  circuits  that  require  the 
10-5  VCC.  Also,  since  the  LM317  re- 
quires at  least  2  volts  over  the  regular 
ed  output.  yOLj'll  lose  regulation  of  ttid 
VCC  tine.  Figure  1  shows  hiow  simple 
this  is  to  do:  Cut  a  trace  on  the  PC 
board  and  run  one  wire.  Thai's  all 
there  is  to  It. 

MFJ  made  this  modification  to  later 
production  runs  Of  the  ngs.  If  youVre 
not  sure  rf  yours  has  ttie  modir»cation. 
check  pin  ^  of  the  LM386  with  your 
VOM.  If  the  VOM  says  10.5  volts,  then 
tt>e  nxKliflcation  has  not  been  ddne.  II 
the  VOM  reads  the  suppJy  voltage, 
say  13  volts,  then  the  modification  is 
factory -installed. 

New  Front  End 

Atthough  you  can1  reaJty  can  this  a 
modifrcaljon,  the  cirouits  shown  in  Fig- 
ure 2  may  improve  the  performance  of 
your  receiver.  The  values  are  tor  the 
40  meter  band.  The  circuit  at  the  top 
seems  to  work  the  best  for  me.  Id  rec- 
ommend It  over  the  other  one.  but 


rtnlwnna 


ToMur 


CI  C3 


C2  100T9F 


To 


L3..  34  tUf1» 


j^rr 


&igte  ««wd  40  ir«v  bom  wd 
Unt-es^ecn 


fiSgwne  2.  Two  circuits  that  might  be  afc/e  to  improve  your  receiver's  front  er^d.  Val- 
ues Bhowf)  are  for  40  meters^ 


TP2 


DC  input  13  S  V   Pummt 


0 


uutaae 


Before  the  modification 


IPS 


0 


In 


U017 


Acf] 


Om 


I ^^^1 — 


1 


> 


10.5  votts 
to  nasi 


22 


jAnarinoctticatiofi 


=^ 


Out 


LMsea 


Egi/m  t.  Modification  to  correct  tow  aucfio  gain  in  some  MFJ  QRP  f^igs. 


that.  too.  works  quite  well.  Use  the 
cores  specified  fn  the  schematic.  The 
variable  capacitors  are  Arco  trimmers. 
1  used  hamfest  junk  boK  units  In  my 
project 

For  transceiver  operatioa  you  must 
break  the  connection  between  the 
receiver  and  the  transmitter  Insert 


the  filler  In  the  receiver's  antenna 
line  only.  If  your  transceiver  has  diode 
switching,  with  a  pick-off  from  the 
transmitter's  output  filters,  you  may 
have  to  pfay  with  the  values  of  the 
filler's  components.  I  find  this  circuit 
really  keeps  the  unwanted  critters 
out  of  my  direct  conversion  receiver. 


ToR3 

A 


Switch  R3  before 
modification 


■^-       Coax  'narrow' 


Coax  '^ide' 


ToR3 

I 


Switch  R3  before 
modifk:ation 


Coax  "narrow* 


BANDWIDTH  COhJTROL 


Coax  "wide" 


Figure  3.  A  modification  for  your  Heath  HW-9  which  wiU  repface  the  selectivity 
switch  with  a  pot 

73  Amateur  Radio  Today  •  July,  1 994  55 


Although  !  don't  have  one  In  my 
shack,  I  wonder  If  either  oJ  these  filters 
would  make  the  Heath  HW-7  receiver 
worth  using?  Again,  yoy  would  have  to 
break  ihe  connections  between  the 
transmitter  and  the  receiver.  This  will 
require  cutting  some  PC  board  traces. 
Donl  try  It  if  you're  not  up  to  this  type 
of  modificatjon. 

No  matter  how  you  use  these  fit* 
ters,  they  will  work  best  if  you  install 
them  In  some  sort  of  shielded  box.  I 
use  double-sided  PC  board  for  my 
boxes.  BuIh  the  stuff  is  really  hard  to 
get  into  if  you  solder  all  the  way 
around  the  edges. 


or  rtmy  not  like  the  results. 

The  second  modification  I  urns  the 
S-meter  into  an  expanded  voltmeter 
so  you  can  track  battery  voitage.  This 
is  a  great  idea  it  you're  working  on 
battery  power  In  the  outback.  This  cir- 
cuit is  also  from  Germany.  The 
schematic  for  thts  modification  is 
shown  in  Figufe  4.  Notice  the  values 
of  the  resistors.  The  values  lisled  are 
only  a  gukje:  you  will  need  to  change 
the  vaiwes  to  suit  your  HW-9,  Seems 
Heath  did  not  use  Ihe  same  meter  in 
all  produciion  runs. 

A  doyble*pole  doubte-throw  switch 
selects  between  S-meter  and  volt- 


'Wo  matter  how  you  use  these  filters, 
they  will  work  best  if  you  install  them  in 
some  sort  of  shielded  box, " 


A  mtiftt-pole  switch  could  be  used 
to  sefect  the  proper  front- end  filter  tor 
several  different  bands.  All  the  fiiters 
wouid  need  to  be  shielded  from  each 
other  in  one  box.  Again,  doub^e-slded 
PC  board  is  qmgx  k)rfhis. 

HW-9  Mods 

Here  are  two  more  modifications 
for  &ie  Heath  HW-9  QBP  trartsceJver. 
The  first  one  is  rather  simple  and 
IVe  seen  this  same  modification  done 
to  the  iHW-8,  ft  requires  removing  the 
seEectivity  switch  and  replacing  it  with 
a  pot.  In  this  case,  the  switch  Is 
replaced  with  a  22k  pot.  Since  this 
modificalion  came  from  DL7GK  in 
Germany,  Td  say  you  could  get  by 
with  a  standard  20k  pot  and  have  the 
same  effect  as  with  a  22k  pot,  8y  us- 
ing a  miniature  pot,  you  might  be  able 
to  squeeze  it  to  fit  on  the  front  pan^l. 
The  circuit  is  shown  in  Figure  3.  It's 
about  as  simple  as  they  come.  You 
may  want  to  hard-wire  this  modinca* 
tion  tn  and  give  it  a  try  before  you 
drill  any  holes  in  the  HW-9.  You  may 


meter.  The  entire  circuit  can  be  built 
on  a  small  hunk  of  perf  board.  A  PC 
board  couid  also  be  drawn  out,  too. 
Motice  the  use  of  the  meter  scale.  This 
way,  you  don't  have  to  recaiibrate  the 
meter  and  you  don't  have  to  rework 
the  meter's  face.  Take  a  look  at  Rgure 
4.  You'll  see  what  I  mean  by  using  the 
meter's  face  to  read  voitage.  Nope,  it's 
not  a  fluke  77.  but  it's  better  than 
nothing.  And-  you  don't  have  to  carry 
another  pfece  of  gear  with  you  when 
you  travel. 

Since  I  have  sold  my  HW-9,  I  can't 
say  if  either  of  these  modifications  work. 
Proceed  oti  yoyr  own  with  ca  Jtk)n! 

Longer  Columns 

Thanks  fn  part  to  my  new  toy.  an 
Apple  Powerbook,  I've  been  able  to 
expand  on  some  of  these  columns^ 
Having  the  computer  with  me  at  worit 
has  aliowed  the  column  to  grow  a  bit. 
Since  1  work  in  a  factory,  the  extra 
time  between  setups  has  proved  very 
useful.  That's  why  I've  been  able  to 
make  these  columns  longer. 


12VDC 


11  VDO 


13VDC 


HW-9  S-^iieter  face 


6K 


Red  wire  from 
PCB  (meter  +)  4- 


4.7  Vort 

-^ V\A— I 


Brown  wire   ^ 
ffoiTiPCB 

(meter  -) 


WV^T — w^ 


4K 


5K 


To -1-12  insfd©HW-fl 


Figure  4.  Schematic  for  modifying  the  H&ath  HW-9,  turning  the  S-met&r  into  an 
expanded  voitmeter  so  you  can  imck  battery  condition. 


Damn,  It's  Coldt 

n*s  ookJ  up  here  in  the  mWdte  bay 
crane!  Yupl  This  is  January  19  and  rfs 
the  coldest  day  on  record.  As  i  work 
on  this  column,  all  the  major  electricity 
suppliers  have  asked  heavy  industry 
to  reduce  their  electrical  demands.  In 
fact,  our  factory  has  been  ordered  to 
shut  down  so  the  energy  can  be  used 
for  residential  customers,  tn  some 


parts  of  West  Vtrglnfa.  there  have 
been  rolling  blackouts  for  up  to  one 
hour 

If  you  happen  to  enjoy  running 
QRP,  you'll  never  notice  the  biack* 
outs!  Why.  an  HW-9  or  a  MFJ  9020 
and  a  battery  wtil  keep  you  on  the 
air  for  a  very,  very  long  Itme.  Thafs 
especiariy  true  if  you  don't  smoke 
ctgars! 


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Hie  SGJDOO  HF  transceiver  Is  type  accepted  for  coiTKmerclal  and  marfne  servica 
made  wiih  ifadilJonigl  U^S.  cflmmercial  radio  quality  (and  of  course  H  C3n  be  used 
on  iho  hem  bai^d-s  also).  While  Ihe  Japanese  radios  have  2  Tnal  transistors  Ihai 
fltfaiTi  10  put  out  too  watis  on  tho  low  li^tnds  and  only  75-35  wans  on  len  meters. 
(fio  SGaOOO  tias  4  larQe  iransJaiofs  ihat  loaf  along  at  150  wattfi  ort  AU.  THE 
BANDS  (MCLUDING  TO  METEflSI  Some  o(  the  SG2000  features  are:  1)  A 
cotilToi  head  rem  stable  (no  special  kit  necessajv)  up  lo  150'  away  Irom  Ihe  rig, 
pg^r'i^ct  lor  aiflornobii^^  and  boats.  iJp  to  B  heads  can  be  utilized  and  used  d& 
intercoms  also.  2)  TMe  largesi  display  ol  any  HF  transceiver.  3)  614  pre^ 
programmed  memortes  arid  100  user  pfQgrammatii&  memories.  4)  opafabie  (rom 
-50F  i'AbC)  to  re5F  (+85C).  You  wanj  quality  righl?  Hera  Is  what  EVERY 
SG2000  rrujal  endurg  before  they're  shipptjd  frfim  me  faclory:  1)  They're  laclory 
allQnod,  a)  EVERV  SGMOO  ts  keyed  down  al  lull  pow&r  (CW  1&0  Walls)  InJo  en 
Open  anienna  lor  at>out  1Q  seconds,  then  connected  to  a  srxorted  antenna  and 
hayed  down  lor  an  ad^iilional  10  seconds.  3]  EVERV  SG200D  is  pul  In  thft 
-BUFlM'lN"  rack  and  keyed  dovm  tor  24  tmurs  non-slop  at  ful!  power  CW.  Don'l  try  that  with  the  foreign  radios.  A)  EVERV  SGSOOO  te 
ltT4Sn  ne'Che^hed  fOJ"  ai^^^^mem  snd  pui  In  (he  'TORTURE  RACK"  lArtic-^e  they  are  t<eyed  on  and  off  every  10  seconds  tor  2A  hours.  S| 
The  SG200CI  is  then  reHjvaluated  and  all  control  functions  are  verified  to  ensure  Jhat  the  microprocessor  is  up  to  spec,  THEN  AND 
Ot^LY  THEN  IS  THE  SG2000  ALLOWED  TO  LEAVE  THE  FACTORY. 

Ihe  bottom  line  is  price,  you  Know  how  expensive  comnneftia^  ngs  are  normatiy.  we  are  seinng  the  SGSOOO  BELOW  DEALER  C0S7 
ai  oriiy  Si  385 .00  each!!  Thats  a  S400-00  savir^gs'  We  gusranlee  the  besi  price. 


j^DciSfpfoj? 


Tilt  SG23€  SMART-TUKER  is  Ihe  best  HF  aulorjnef  at  any  price,  ant^  Jo 
promole  a  pn>dLJCt  D^l  is  rrade  m  itte  USA,  we  re  oiretiTig  It  al  the  duaranleed 
Iwsl  price  of  onty  S449.00"  WHY  THE  50230?  BECAUSE:  When  you  ttine  an 
antenna  fil  irs  base  you  are  resonsottig  me  antenna,  instt^ajd  ^  pst  matchmg  the 
coax  lo  *m  racso  as  vtm  other  funeis  such  ss  tm  AT50.  etc.  Tik  nesutt  VQUfl 
SIGNAL  GETS  OUT  MliCH  BETTER.  T>ie  Kenwood  ATSQ.  AT450  and  other 
stmi^  tuneti  can  of^  ma^h  2-.\  m$mzidhes  fVES  only  ^^SQ  forgei  maich^ 
anylMns  Dul  a  fairty  (Secent  anfeona,  Ihe  SG230  can  match  tnarm  O.S  Otni  lo  10 
iciotwn  ahl>ervia£  (up  to  a  200:  i  misniajch).  so  it  can  eas^  matcn  random  iMlf««. 
dipola.  rttifvgiutlH^  shopfwg  caits,  OIe.  The  resuM  MOflE  POWEH. 


To  erder.  mm  check  or  morwy  oidtc  wfh  mSOtot  st^i^af^  dlen^  iiib  your  shppif^  acbtiB}  (aviy  m  US  Pvm 
Ollict  Bok«%.  UPS  mfd  nod  dr^vr)  and  TiJaphong  nuiriifrtD: 

Joe  Brancato 

THE  HAM  CONTACT 

PO  Box  3624,  Depi  73 
Long  Beach,  CA  90803 

CA  ncMkjnii  Add  i  1^4%  S«I«T«il  AlHia  Hatt^an.  and  Canatiui  Restlems  pl^se  send  \J  S  MonoY  O^ 
T  £17.101  Jbr  ahfipng. 

Sefvmg  Ihe  LQfiD    W  ythJ  wisft  mtwe  rniJwmatlon  p'easc  sefid  a  SASE  to  ihe  above  address.  For  COO  onders.  calf 
Slic«  1987         t310)433-&e60,  Qui^Jde  oJ  GA  Orders  Only  cat  (6CM}]Sa34iAM4  and  leave  a  message. 


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73 Amaleur Radio  Today*  J\j\y,\B94  57 


Ntitnber  t7  on  your  FeedbacK  card 


M^k  ntnnaer  if  an  your  reeaDacn  ua 

Packet  &  computers 


Digital  Amateur  Radio 


Jeffrey  Slomarj  N1EW0 
c/o  73  Magazine 
70  Route  202  North 
Peterborough  NH  03458 

OK*  Tm  back  after  a  month's  ab- 
sence. The  cofumn  tried  to  compete 
with  moving  and  losL  Moving  is  one  of 
my  least  favorite  activities,  and  this 
one  was  worse  than  expected.  On  tfie 
other  hand,  we're  here  and  things  are 
smoothing  out. 

This  month  1  have  a  few  things  to 
deal  with,  so  I  wiii  not  be  doing  a  "reg- 
ular" instaliment  of  the  TCP/tP  series. 
instead,  I  need  to  cover  some  '■admin- 
istrative" information,  and  f'ii  also  dis- 
cuss some  iP  odds  and  ends  that 
should  be  interesting. 

First,  the  administrative,  Uar^y  of 
you  write  to  me,  both  on  paper  and  via 
the  bit  stream^  I  really  appreciate  hear- 
ing from  you,  and  read  everything.  Re- 
plying can  ba  somewhat  more  difftcuil. 
i  am  not  ignoring  you.  First,  I  get  Email 
from  my  other  writing  work  as  we  if, 
and  tine  combination  of  73  mail  (you 
guys  aren't  shy),  and  other  traffic  can 
be  overwhelming  at  times.  1  reaily  ap- 
preciate all  of  the  feedbacl^— praise 
and  not-p raise— but  t  just  don't  have  a 
good  way  to  repJy  to  everyone. 

Second,  many  of  you  have  written 
asking  for  reprints  and  execu tables.  I 
cannot  provide  these.  Reprints  com© 
from  73— cali  (603)  924-0058  to  obtain 
these;  reprints  are  $3  per  article ^  back 
issues  are  $4  each.  For  the  executa- 
bles,  I  do  not  have  the  time  to  copy 
and  maii  disl<ettes.  I\flany  of  you  have 
sent  prepaid  diskette  mailers  and 
disks.  I  have  not  been  abEe  to  do  any- 
thing with  these.  You  can  get  any  exe- 
cutabie  or  text  file  I  describe  on  the  73 
BBS  at  (603)  924-9343.  300-2400 
baud,  8  data  bits,  no  parity,  one  slop 
bit. 

Now  wait  a  minute— I  know  that 
many  of  you  have  tried  to  find  these 
files  on  the  BBS  and  they  just  haven't 
been  there.  I  must  take  the  biame  for 
Ihfs,  but  1  will  be  changing  It. 

Now,  a  personal  note  to  an  un- 
known reader:  II  you  sent  me  some 
cash,  please  write  again  and  iet  me 
know  who  you  are.  You  can  identify 
yourself  by  teiling  how  much  you  sent 
and  why.  Some  time  ago.  a  bunch  of 
mail  that  included  a  collection  of 
checks,  diskettes,  and  mailers  got 
separated  from  the  letters  that  went 
with  them.  I  do  not  cash  checks  sent 
to  me,  and  I  want  to  return  your 
money, 

OK— Here's  the  last  bit  of  adminis- 
trative nonsense:  how  (and  how  not} 
to  contact  me.  1  can  be  reached  three 
ways: 

1.  Email  on  the  Internetr  This  is 
the  preferred  method  of  contacting  me 
and  stands  the  best  chance  of  getting 

58  73  Amateur  Radio  Today  •  July, 


a  response.  Those  of  you  who  sub- 
scribe to  online  services  like  Com- 
puServe, Genie,  AOL,  Prodigy,  BIX, 
Delphi,  and  the  like  can  all  reach  me 
at  this  address.  The  exact  method  can 
vary  considerably— get  help  on  your 
system  in  addressing  mail  to  the  Inter- 
net. My  Internet  address  is:  jslo- 
man@bix,com. 

2.  Paper  Mall:  This  is  an  accept- 
able way  of  contacting  me  if  you  do 
not  have  access  to  electronic  mail 
(you  should ^  you  know).  Please  write 
to  me  c/o  73  magazine,  at  the  address 
listed  above. 

3*  Packet  Mall;  Of  course  I  want  to 
hear  from  you  via  packetl  But,  I  cannot 
answer  questions  about  the  cotumn  or 
magazine  this  way.  Too  many  of  you 
write  to  me  via  packet  radio  and  ask 
things  that,  were  1  to  answer,  would 
constitute  doing  business  on  the  radio. 
This  is  */erj/ frustrating:  You  have  good 
questions.  I  am  no  Mg  no  ring  you,  I  just 
can't  answer — sorry.  Please  send  me 
packet  traffic  for  fun,  to  try  it,  to  let  me 
know  that  youVe  got  something  work* 
ing.  But  if  you  want  me  to  respond, 
don't  mention  the  magazine,  please. 
So,  with  that  preamble,  address  your 
packet  traffic  to  me  at: 

N1EWO@N0ARY.#NOCAL.CA.LJSA. 
NOAM 

{Note  the  NOAM  at  the  end — for 
North  America.  Do  not  use  NA,  the 
people  in  Namibia  are  not  too  happy 
with  the  folks  that  do>) 

On  to  other  business,  Firstp  lei  me 
tell  you  about  the  latest,  and  last  DOS 
version  of  JNOS:  1.10c.  WG7J  has 
announced  that  he  is  now  concentrat- 
ing on  developing  a  WIN32  version  of 
JNOS  (a  very  good  thing  indeed),  and 
so  UOc  is  the  last  version  that  he  will 
release  for  DOS.  Where  can  you  get 
it?  Well,  as  of  this  writing  you  cannot 
get  it  on  the  73  BBS.  You  can  get  tt  via 
anonymous  FTP  from  several  of  the 
ham  archives.  I  will  avoid  specifying  a 
site— this  has  gotten  me  in  trouble  in 
the  past.  You  should  be  able  to  get  it 
from  places  tike  CompuServe  as  well, 
but  I  can't  guarantee  that.  JNOS  is 
very  widely  distributed;  ask  around. 

Version  1, 10c  adds  several  fea- 
tures which  wit]  be  completely  new  to 
those  of  you  who  are  using  non-re- 
lease (x)  .10  versions.  First,  there  is  a 
very  useful  status  bar  which  displays 
using  the  top  three  lines  of  the  display. 
It  offers  some  nice  at-a -glance  info: 

On  the  first  line — time  memory  sta- 
tus number  of  sessions  using  the  vari- 
ous sen/ers  (conv,  tinks,  bbs,  fwd,  ftp, 
smtp),  a  list  of  active  terminal  ses- 
sions, specified  by  number;  these 
bfink  when  tin  ere  is  text  waiting  in  a 
session  not  currently  displayed. 

On  the  second  line  is  a  list  of  cur- 
rent BBS  users  by  callsign.  Each  cafl- 

1994 


sign  IS  preceded  by  a  character  Indi- 
cating which  activity  the  user  is  en- 
gaged in, 

On  the  third  line  is  information 
about  the  currently-displayed  session, 
including  the  connection  and  informa- 
tion about  retry  timers. 

(Users  of  Wf^JOS  are  already  famil- 
iar with  this  type  of  status  display.  This 
excellent  feature  is  now  available  to 
JNOS  users.)  The  status  display  is 
configurabte  in  two  ways:  color  and 
number  of  lines.  The  specific  colors  of 
the  text  and  background  of  each  line 
are  configurable.  You  can  also  choose 
to  display  one,  two  or  three  lines  ot 
status  information.  Speaking  of  color, 
the  text  display  colors  are  now  config- 
urable at  startup  as  well.  This  is  very 
useful  because  of  another  new  fea- 
ture— a  command  line  in  the  trace  win- 
dow. 

You  can  now  execute  commands 
directly  in  the  trace  window.  This  is 
very  useful,  for  exampfe,  when  testing 
using  ping.  You  can  ping  a  station  and 
see  the  interaction  from  the  very  be- 
ginning. No  more  attempts  at  light- 
ning-fast switches  to  the  trace  window 
with  thie  F9  key  are  necessary. 

There  are  many  other  features  you 
will  find  useful  in  this  new  and  last  ver- 
sion. Get  a  copy  and  give  it  a  try — 
tests  here  show  it  being  very  stable. 

TCP/IP  Routing  Using  Diglpeaters 

You  and  a  friend  want  to  communi- 
cate using  JNOS  on  each  end;  the 
trouble  is,  you  need  to  use  a  digi  to 
make  the  connection,  a  digi  that 
doesn't  know  anything  about  TCP/IP. 
Hmmm,  how  can  you  make  the  con- 
nection? 

The  impossibility  of  using  a  plain- 
old-digi  for  TCP/IP  is  only  a  misunder- 
standing of  how  the  system  operates 
on  amateur  radio.  TCP/IP  over  ham 
radio  has  two  different  layers,  There  is 
a  logical  layer  that  handles  TCP/IP 
messages  and  traffic,  and  then  there 
is  a  hardware  layer.  It  is  m  this  hard- 
ware  layer  that  the  digipeater  lives. 

When  you  attempt  to  connect  to  a 
friend^s  station  which  can  hear  you  di- 
rectly, the  first  thing  your  station  witl  do 
is  to  send  an  ARP  request  over  the 
default  Interface.  ARP  means  Address 
Resotution  Protocol,  and  Is  the  way 
the  an  IP  station  finds  out  the  hard- 
ware address  associated  with  the  IP 
address  which  it  has  been  told.  Let's 
see  how  this  works: 

You  type  leinet  44.48.70.22"  at  the 
JMOS  command  prompt.  JNOS  re- 
sponds by  opening  a  new  session  win- 
dow. At  the  top  of  the  window  is  the 
message  "Resolving  44.48.70,22," 
JNOS  has  Just  transmitted  and  ARP 
request.  This  is  a  broadcast  message 
saying,  "I  need  to  know  the  hardware 
address  associated  with  the  IP  ad- 
dress 44.48,70.22." 

Your  friend's  station  recognizes  its 
address  and  responds,  saying  that 
N1EW0  handles  IP  traffic  for 
44.48,70,22,  Your  station  places  this 
information  in  your  ARP  table,  and  es- 
tablishes the  connection. 

This  is  the  way  that  it  should  work, 
if  stations  can  hear  each  other.  But 


what  if  they  cannot?  In  this  case  we 
can1  rely  upon  the  automatic  ARP  pro- 
cess, and  instead  have  to  make  it  hap- 
pen manually  To  do  this  well  need  to 
make  our  own  arp  entries^  and  also 
add  AX. 25  routing  information.  ARP 
entries  are  soft;  that  is;  they  will  go 
away  v/hen  you  restart  JNOS.  To  make 
them  "permanent,"  put  them  in  the  AU- 
TOEXEC.NOS. 

Here  are  the  facts  about  the  station 
we  wish  to  reach: 

IP  address:  44.48.70.22  hardware 

address:      M1EWO 

(note  that  hardware  address-AX.25 

address) 
digipeater:  KB9BWE 

So  first  let's  make  the  ARP  entry  so 

that  the  station  does  not  have  to  gen- 
erate an  ARP  request  which  could  not 
be  answered.  We  do  this  from  the 
command  line,  using; 

arp  add  44.48.70.22  ax25  niewo  dsp 

arp  the  ARP  command  for 

JNOS 
add  tells  JNOS  to  add  the 

following  information  to  the 

ARP  table 
44.48.70.22  the  host  ID  otthe  station  for 

the  entry  (this  coutd  be 

alphanujneric 

[e.g.:  N1 EWO)  if  you  have 

the  appropriate  entry  in  your 

DOMAIN.TXT  file) 
ax25  tells  JNOS  to  use  the  ax25 

hardware  layer 
n  1  e  wo         th  e  h  a  rd ware  address  of 

the  station  for  this  entry 
dsp  the  name  of  the  interface 

that  should  be  used  for  this 

entry 

Now,  when  you  attempt  to  connect 
to  44.48.70.22,  this  ARP  entry  will  be 
used.  So,  we're  halfway  to  the  solu- 
tion—JNOS  will  now  use  the  correct 
hardware  address  for  NIEWO.  What 
about  the  digi? 

JISIOS  also  maintains  a  routing  list 
for  AX. 25  traffic.  Using  a  very  similar 
technique^  we  add  the  information 
about  KB9BWE— our  digi— to  the 
AX. £5  table.  From  the  JNOS  command 
prompt: 

ax25  route  add  niewo  dsp  kb9bw^ 

ax25        the  JNOS  AX.25  command 
route       the  route  sub-command 
add         tells  JNOS  to  add  the 

fol [owing  information  to  the 

AX.25  route  table 
dsp         the  name  of  the  interface 

to  use 
kb9bwe  the  name  of  the  digi  (more 

than  one  can  be  specified) 

Now,  JNOS  knows  everything  it 
needs  to  about  how  to  reach 
44,4S,70,22  from  your  station.  When 
you  "telnet  44.43.70.22"  it  finds  the 
hardware  address  already  in  its  ARP 
table  and  the  AX.25  n^ute  table  tells  it 
to  use  a  digi  to  get  there- 
More  next  month.  Tit  then  73  de 
NIEWO. 


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Fuf  tenon  CA  92633 

Attenuators  Made  Easy 

Carelylly  planned  deception  can 
make  the  difference  between  a  simpte 
hidden  transmitter  hunt  and  a  real 
challenge.  JusI  as  a  football  team  re- 
lies on  deceplion  to  loll  the  opponent's 
defense,  hiders  in  radio  direcrion  find- 
ing (RDF)  coniests  (called  foxhonis  or 
T-hynIs)  do  Itieir  best  to  cause  hunters 
to  make  incon^ect  assumptions  about 
direction  arxf  distance  to  their  location 

Last  April's  Fullerton  Radio  Club 
mobile  hunl  is  a  good  e)(amp1e. 
WA60PS  and  I  helped  WB6GCT  and 
WB6UZZ  hide  it.  At  the  starting  point, 
our  signal  was  from  the  north  and  was 
quite  weak,  S-meler  readings  were 
about  the  same  with  the  hunters*  yagis 
and  quads  set  to  either  horizontal  or 
vertical  polarization. 

Figuring  that  the  T  was  near  the 
distant  bour>daries.  some  learns  boil- 
ed br  the  freeway  to  head  north.  Gib- 
ers, suspecting  that  we  were  mffectmg 
our  signal  from  the  front  range  of  the 
mountains  25  miles  away,  headed 
east  or  west  on  a  hunch.  All  IS  teams 
lost  the  stgr^al  upon  leaving  the  start- 
ing hil[,  but  they  kept  going, 

AJi  had  tseen  deceived.  Our  T  was 
only  three  miles  north  oJ  the  Start,  on 
the  side  of  a  hill  thai  blocked  the  sig- 
nal toward  the  freeway.  A  paltry  2.5 
microwatts  drove  an  11 -element  beam 
pointed  toward  me  start.  It  was  two 
hours  fater  that  the  first  team  found 
ttie  transmute f.  The  six  teams  that 
managed  to  find  it  that  nighl  had  driv- 
en from  22  to  52  miles.  They  were 
fooied  by  the  careful ly-contro tied  pow- 
er level  and  antenna  position. 

Our  fox  transmitter  put  out  such  a 


Radio  Direction  Finding 

meager  signal  that  a  hunter  could 
drive  from  Ihe  start  point  to  within  100 
feel  of  its  antenna  without  the  S-meter 
ever  registering  full  scaie.  That's  very 
unusual,  since  the  5  to  50  watt  hidden 
transmitters  encountered  on  most  mo- 
bile hunts  usually  pin  hunters'  signal 
irxjicators  when  they  are  several  miles 
away.  Typical  VHF*FM  receiver  S -me- 
ters have  only  a  20  to  30  dB  range. 

Antidotes  for  Overload 

Every  T-hunter  who  gets  bearings 
with  a  directional  antenna  and  S-meter 
requires  some  method  for  knocking 
down  strong  signals  to  Ihe  point  tfiat 
amplitude  char>ges  can  be  discemed. 
But  RF  gain  controls  are  pmvided  in 
only  a  few  VHF  transceivers,  usually 
the  relatively  expensive  mulltmocfe 
models.  If  you  are  thinking  of  purchase 
ing  such  a  rig  just  to  have  RF  gain 
control  for  T-hunting,  be  sure  to  test  it 
before  you  buy.  In  many  cas€S,  lower- 
ir^g  the  RF  gain  control  adversely  af- 
fects S-meter  action.  You  may  not  be 
able  to  take  bearings  with  gain  re- 
duced. 

If  you  enjoy  performing  minor  elec- 
tronic surgery  inside  receivers,  you 
can  add  internal  RF  gain  reduction 
that  won't  upset  S-meter  action.  Con- 
trol the  supply  voltage  lo  the  RF 
preamp  and  first  mister  stages,  or 
change  the  tBas  o(  tfre  FETs  in  these 
stages.  The  "Homing  In'  column  in  the 
March  1989  issue  of  73  Amateur  Ra- 
dio Today  provides  plans  for  a  voltage- 
reduction  internal  attenuation  system 
for  popuJar  VHF-Ff^  transceivers. 

A  simpler  and  much  more  popular 
way  to  knock  strong  signals  down 
lo  size  is  to  connect  an  attenuator 
bO)c  between  your  antenna  and  recetv- 
er  input.  A  resistive  (sometimes  called 
a  "passive")  attenuator  has  several 
shielded  sections,  each  with  resistors 


Photo  A.  You  can  buifd  your  own  resistivB  alienuaior  from  PC  l)03fd  mat&riai, 
switches,  and  resisiors^  Or  you  can  buy  a  finished  unit  iike  this  from  Arrow  Anten- 
na, its  copper-ciad  case  measures  2"  x  4^3/4"  x  1-1/4\ 


Ptioio  B,  inside  view  of  the  Arrow  resistive  ailenuaior  showing  tfre  five  shielded 
ceifs  and  two  hinges  made  from  copper  btaid. 


to  soak  up  the  RF  signal  and  a  dou- 
ble-pole double-throw  switch  to  put 
the  section  into  and  out  of  the  line 
(Photo  A). 

With  the  circuit  in  Figure  1,  you  can 
sel ad  signal  reduction  in  5  dB  steps 
from  zero  to  75  dB.  RF  leakage  across 
the  switch  makes  attenuation  of  more 
than  20  dB  per  section  impractical  If 
your  receiver  is  especially 
well-shielded,  you  can 
add  another  20  dB  section 
to  get  95  dB  maximum. 
More  than  four  2D  dB  sec- 
tions  are  not  worth  the  ef- 
fort, due  to  tt^  likelihood 
of  f^F  coupling  around  the 
attenuator  and  leakage 


through  the  receiver  case. 

This  attenuator  is  an  easy  and  inex- 
pensive construction  project.  Build  the 
multi-cell  enclosure  out  of  doubie-skl- 
ed  unetched  PC  board  material  or 
sheet  copper  Solder  ttie  dividers  aixl 
end  caps  in  place  with  a  continuous 
bead  of  solder  before  mounting  the  re- 
sistors,  connectors ^  and  switches. 


Figure  1.  Schematic  diagram  of  a  simpie  five-section  resistive  attenuator  for  T-hunting  on  any  ham  band  from 
160  meters  through  70  centimeters,  l^esistor  vaiues  are  /n  ohms.  Switches  are  shown  in  down  (attehuation  out) 
position. 

60  73 Amafeur Radio  Today*  July,  1994 


Photo  C,  The  Arrow  Antenna  offset  attenuator  is  in 
a 2-3/3" X 3-3/4' X  Vptasticbox. 


From  RDF 

Antenna 


Out 


Mixer 


+V 


To    Receiver 


Attenualion 
Control 


1 


1    MHz 
Osc. 


Figure  2.  Bfock  tHagmm  of  the  external  offset  attenuator. 


Do  not  secure  the  back  cover  with 
a  long  solder  bead,  because  that  will 
make  it  d  iff  feu  It  to  open  for  repairs.  In- 
stead, make  hinges  out  of  braid  mate- 
rial  arMJ  install  ttiam  as  shown  tn  Ptxjto 
B,  Bott  the  cover  closed  or  fasten  it 
with  copper  tape.  The  hinges  hold  ttie 
cover  arxl  preven!  unwanted  leakage 
and  coupling.  A  hinge  in  each  cell  \s 
ttest 

The  resistor  values  shown  in  Figure 
1  ensure  that  the  receiver  and  anten- 
na remain  terminated  with  the  same 
impedance  as  the  SO-ohm  coax  line  at 
all  attenuation  levels.  Use  only  ca^tKin 
composition  or  caition  film  resistors 
*or  RF  attenuators — never  wi rewound 
or  metal  film  types. 

Quarter- wall  res[stof&  are  OK,  but  I 
prefer  half -watt  parts.  They  withstand 
accidental  transmissions  for  longer  pe- 
riods. It's  even  better  to  use  1  or  2 
watt  resistors,  but  installing  them  in 
the  cramped  ceEl  space  is  very  ditficull. 
Keep  all  resistor  leads  and  jumper 
wires  as  stiort  as  possible.  Jumpers 
between  ceHs  are  straight  rnsuiated 
wires  passing  through  small  holes  in 
the  dividers. 

Good  quality  slide  switches  give 
belter  BF  performa,nce  at  VHP  Ihan 
toggfe  switches,  but  they  require  a 
rectangular  hole  and  are  less  liquid- 
proof  than  toggle  swttches*  which  I 
use.  Subminiature  or  micro*mini  size 
toggle  switches  tit  and  work  better 
than  miniature  types,  but  they  are 
more  fragile.  In  18  years  of  T-hunting 
use.  I  have  never  accidenialEy  burned 
oul  any  of  the  ha  If*  watt  resistors  in  my 
home-brew  attenuator,  but  f  have  re* 
placed  several  subminiature  toggle 
switches  that  wore  out  or  were  dam- 
aged. 

BuHd  or  Buy? 

Commercial  resistive  attenuators 
are  available,  but  nr^ost  are  expensive 
precision  units  for  laboratory  measure- 
ments. Many  do  not  tisve  enough  20 
dB  sections  for  T-hunting.  Neverthe- 
iess,  it  is  a  good  idea  to  watch  al  swap 
meets  and  surplus  outlets  for  suitabre 
ones  at  bargain  prices. 


T-hunting  enthusiast  Ailen  Lowe 
N0IMW  now  sells  attenuators  as  part 
of  his  Arrow  Antenna  line  of  productS- 
His  resistive  mode!  has  the  same  con- 
figuration as  shown  in  Figure  1.  The 
case  is  made  from  Rberglas  PC  board 
materia],  tt  uses  slide  switches  with 
gold  contacts  and  quarter- watt  resis- 
tors. Bolts  arKl  wing  nuts  hold  the  rear 
cover,  so  it  is  easy  to  open  for  repair. 
You  can  choose  either  UHF  (80-239) 
or  BNC  connectors  when  you  order. 

1  tested  the  unit  in  Photo  A  on  the  2 
meter  band  with  a  well-calibrated  sig- 
nal generator  Perforrrrarrce  was  typi- 
cal of  T-hunt  attenuators.  Insertion 
loss  wiih  no  atlenuation  was  2  dB. 
Each  step  had  accuracy  ol  1  dB  or 
better.  Maximum  attenuation  with  all 
sections  switched  in  was  71 .5  dB. 

To  Sotve  Leakage,  QSY 

Handie-talkies  and  scanners  are 
notorious  for  poor  case  shielding.  A 
passive  attenuator  cuts  down  the  sig- 
nal level  tnio  the  antenna  jack,  but 
strong  signals  wilt  still  penetrate  the 
case  and  pin  the  S^meter.  One  way  to 
gel  bearings  on  nearby  foxes  with 
these  sets  is  to  convert  the  strong  on- 
frequency  signal  into  a  weaker  off -fre- 
quency signal.  Then  you  can  tune 
your  receiver  to  the  offset  signal  and 
fT^asitre  its  strength  versus  direction. 

Figure  2  is  the  block  diagram  of  a 
simple  unil  for  level-controlled  fre- 
quency conversion.  When  this  scheme 
was  ohginaEly  descnbed  in  OST  maga- 
zine. Novemt>er  1992,  by  Anjo  Een- 
hoom  PA0ZR.  it  was  called  an  active 
attenuator.  Since  there  are  other  kinds 
of  attenuators  that  are  also  called  "ac- 
tive,^ I  prefer  to  call  tt  an  offset  attenu* 
ator  That  temi  describes  how  it  solves 
case  lealcage  by  offsetting  the  fre- 
quency. 

An  offset  attenuator  consists  of  a 
local  oscillator  (LO)  connected  to  a 
diode  mixer  through  the  attenuation 
control.  The  higher  the  LO  ieveL  the 
higher  the  amplitude  of  the  offset  sig- 
nal applied  to  the  receiver.  To  Increase 
atlenuation,  decrease  the  LO  signal 
Into  the  mixer  with  the  control. 


Arrow  Antenna*s  new 
attenuator  line  includes 
an  improved  version  of 
the  PAOZR  design  {Pho- 
to C).  Instead  of  a  500 
kHz  L-C  oscillator,  the 
Arrow  unit  features  a  1 
MHz  SaRonIx  crystal 
clock  rnoduie,  which  has 
higher  accuracy  and  sta- 
bilily  1  MHz  is  a  good 
choice  for  the  frequency 
offset,  because  it  is  easy 
to  remember  and  pro- 
gram into  your  radio. 

The  trade-off  tor  im- 
proved stability  is  higher 
supply  current,  appfoxi- 
mately  35  mjlliamperes. 
A  three-terminal  regula- 
tor provides  5  volts  to 
the  LO,  so  performance 
IS  stable  with  battery 
voltage   down   to   6.7 
volts.  A  9-volt  alkaline 
batlery  should  power  the 
unit  for  at  least  12  hours.  Arrow  does 
not  provide  a  power-on  or  battery  con- 
dition indicator,  but  there  is  room  to 
add  them  if  you  wish. 

The  unit  I  tested  was  one  of  the  first 
made  by  Arrow,  and  did  not  include  an 
instruction  sheet.  No  problem^it  is 
very  easy  to  use.  Using  Bf^C  jumper 
cables,  hook  it  between  your  direction* 
al  antenna  and  receiver  The  connec- 
tors are  not  labeled.  With  the  simpie 
1N4148  diode  mixer  In  the  Arrow  unit, 
it  does  not  matter  which  port  goes  to 


the  antenna  and  which  to  Vh^  receiver. 

In  my  tests  on  2  meters,  insertion 
loss  of  the  swilched-off  unit  was  0.Z 
dB.  On-frequency  attenuation  with 
power  on  ranged  from  7  to  17.5  dB 
with  adjustment  of  the  attenuation 
control.  Tuning  the  receiver  up  1  UHz 
gave  attenuation  of  11.5  to  101  dB 
over  the  control  range. 

The  LO  module  puts  out  a  TTL 
square  wave,  its  harmonics,  especially 
odd  multiples,  are  very  strong.  You 
can  tune  up  or  down  in  1  MHz  steps 
and  hear  the  target  signal  at  varying 
attenuation  levels.  Untortunaleiy  ttiis 
means  that  the  chance  of  interference 
from  cross-modulation  products  Is 
much  greater  than  if  the  oscillator 
put  out  a  pure  sine  wave.  For  exam- 
ple, if  you  are  hunting  a  T  on  147.48 
MHz,  you  will  get  interference  from 
strong  pagirtg  transmitters  on  152.48 
MHz, 

Figure  3,  which  charts  my  mea- 
surements of  minimum  attenualion  at 
the  10  closest  offset  frequencies,  can 
help  you  predict  the  level  of  cross- 
modulation  interference  and  select  the 
best  offset  frequency  to  use.  Generally 
speaking,  cross-mod  is  less  severe 
when  your  offset  is  an  odd  multiple 
away  From  the  desired  signal  and  an 
even  mult^e  away  from  the  undesired 
Signal,  tn  the  example  above,  the  pag- 
ing transmitter  will  cause  stn>ng  QRM 
to  the  149.43  and  151.48  offset  signal, 
but  much  less  Interference  to  148.48 
and  150.48. 

Amow  literature  says  that  tiie  unit  Is 


60  T 


50  - 


DD 


40    - 


«    30    - 


< 
E 

E 


20    - 


10 


0 


$ 

o 

O 

N 

N 

1—    ojrr>^i-ncDN.00ff>O 


Figure  3.  The  Arrow  of^^  attenuator's  square  wave  iocal  oscitiator  produces  a 
multitude  of  hQferodyne  signals  at  1  MHz  intervais  with  different  levets.  This  chart 
shows  the  retative  amplitudes  at  the  receiver,  with  respect  to  the  input  signal  tev- 
ei.  Attenuation  control  is  set  to  tninimum. 

73  Amateur  Radio  Today  •  July,  1 994  61 


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not  suitable  for  hynling  a  fox  on  an  ex- 
act 1  MHz  multiple  (such  as  147.000 
MHz),  due  lo  ORM  from  harmonics  ot 
the  oscillator  The  harmonics  are 
strongest  ai  minimum  attenuation  set- 
ting. They  wert  lull  scale  on  2  meters 
'm  my  fTx>blie  seiup.  and  half  to  ttiree- 
quarter  scale  on  ttie  222  and  440  MHz 
barxis.  However,  with  extra  care  in  ad- 
justing the  attenuation  control.  I  was 
stil!  able  to  get  bearings  on  a  strong 
test  signal  on  147.000  MH2.  LO  har- 
monies  are  a  problem  when  an  even* 
megahertz  fox  signal  is  just  strong 
enough  to  pin  the  S-meter.  but  they 
will  not  cause  trouble  when  you  get 
very  close  1o  the  T  and  raise  ttie  atten- 
uation control  settir^g. 

There  is  no  isolation  between  the 
mixing  diOde  and  your  antenna.  Offset 
signals  not  only  go  inlo  your  receiver, 
tkit  they  also  go  back  to  your  RDF  an- 
tenna, wtiere  they  are  radiated.  This 
may  cause  Cfoss^modutation  ORM  to 
neart>y  receivers,  even  outside  the 
ham  bands. 

The  Bottom  Line 

An  oflset  attenuator  is  excellent  for 
on-foot  foxhunting^  whether  you  use  it 
for  "sniffing"  at  the  end  of  a  mobile 
hunt  or  for  European/Asian  style  in- 
ihe*woods  radiosports.  It  works  with 
directional  antennas  or  Just  with  a  rub- 
ber duckie  as  an  aid  to  the  "body 
shield"  maneuver. 

On  the  other  hand,  a  resistive  at- 
tenuator Is  a  better  choice  for  mot)ile 
RDF,  in  most  cases^  Passive  attenua- 
tors avokJ  the  problems  of  images  and 
re- radiation  that  are  far  more  harmlul 
in  mobile  situations  than  on  fooL 

Usually,  the  only  time  an  offset  at- 


tenuator is  superior  to  a  resistive  al- 
lenualor  in  a  mobile  setup  is  when  you 
are  ctose  to  a  powerful  hidden  T  and 
your  mobile  rig  is  overioaded  with  all 
resistive  attenuation  steps  in.  In  such 
a  case,  connect  tt\e  offset  attenuator 
tietween  the  resistive  attenuator  and 
the  mobile  fig.  To  minimize  re- radia- 
tion ORM  from  your  mobile  RDF  an- 
tenna, set  the  resistive  attenuator  to 
20  dB  or  more. 

Remember  that  an  offset  attenuator 
does  not  significantly  reduce  the  level 
of  on-frequency  slgna!  Into  your  radio, 
so  It  does  not  provide  protection  tor 
your  receiver's  front  end.  If  you  touch 
your  RDF  antenna  1o  the  antenna  of  a 
powerful  fox  transmitter,  you  may 
damage  both  the  receiver  and  the  off- 
set attenuator. 

Avoid  transmitting  through  any  ex- 
ternal attenuator.  You  may  damage 
tt^  resistois  in  a  passive  unit.  You  will 
transmit  strong  spurious  signals  if  you 
key  up  through  the  olfset  attenuator, 
and  you  may  bum  out  ils  diode.  Dis^ 
connect  the  mike  if  you  are  T-hunting 
with  a  mobile  ng.  Set  the  power  output 
down  to  the  lowest  possible  level  on 
your  hand-held,  Fortunatelv,  if  you  for- 
get and  cause  a  failure,  repairs  are 
easy  and  inexpensive. 

Mali-order  price  of  the  Arrow  offset 
attenuator  is  S59.  The  resistive  attenu- 
ator sells  for  $49,  For  more  informa- 
tion on  Arrow  products,  txintacl  Arrow 
Antenna.  1461  Peacock  Place,  Love- 
land.  CO  80537:  (303)  663-5485,  To 
contact  me.  wrile  to  my  California 
address  under  the  headir^.  Remem- 
ber that  a  self-addressed  stamped 
envelope  for  the  reply  is  always  appre- 
ciated. 


Sell  your  product  in  73  Amateur  Radio  Today! 
Call  Dan  Harper  at  1-800-274-7373.  | 


Ham  help 


Number  19  on  your  Feedback  C3fd 


CVRCLE  33  ON  FIEADEH  SERVICE  CARO 

62  73  Amateur  Radio  Today  •  July,  1 994 


We  am  happy  to  provide  Ham  Weijp  iistirygs  free  on  a  space  avaiiable  basis.  To 
n^ake  our  job  easier  and  to  ensure  ttiat  your  Hsting  is  correct  please  type  or  print 
your  request  deariy.  douGfe  ^aced,  on  a  full  (8  ^fT  x  ti'}  sheet  of  paper.  You 
may  also  upload  a  tisting  as  E-maif  to  Sysop  to  the  73  BBS/Sp&ciaf  Bver}ts  Mes- 
sage Area  ^I't.  (2400  baud  &  data  tits,  no  parity,  t  slop  bii  (603}  924'9343}. 
Pfease  indtcafe  if  it  is  for  pubitcatfon.  Use  upper-  and  lower-case  fetters  where 
appropriate.  Also,  print  numbers  carefully— a  f,  for  example,  can  ije  misread  as 
the  letters  f  or  i,  or  even  the  number  7.  Specifically  mention  that  your  message  is 
for  the  Ham  Help  Column.  Phase  remember  to  ackriowiedge  responses  to  your 
requests.  Thank  you  for  your  cooperation. 


I  have  recently  "inherited"  a 
RADIO  SHACK  TRS-80  Model  III 
with  no  software,  operating  sys- 
tem or  docurnentation.  My  local 
Radio  Shack  has  been  unable 
to  heip  nne.  Since  I  am  planning 
on  dedicating  the  machine  to 
packet.  I  knew  (  would  be  bet- 
ter off  relying  on  my  fellow  Ama- 
teurs. I  will  gladly  reimburse  you 
for  your  expenses.  Thank  you, 
Johnny  E  Brown  NiQQS.  RO, 
Box  1305-226,  Brunswicfi  ME 
04011. 


I  need  the  schematic  for  HEATH 
Company  Model  SA-5010  Keyer, 
Your  help  will  be  greatly  appreciat- 
ed. Tom  Stepanov  RA6AR/WN1R, 
P.O.  Box  555,  Sochi'355,  Russia 
354355^ 

WANTED:  Manual  (for  a>py)  for 
ICOM  IC*245  2  meter  transceiver.  I 
only  need  the  sideband  adapter  in- 
formation, or  any  computer  inter- 
facing information,  Oaude  J.  Cook 
KD6NFJ,  34 A  Springbrook  Rd., 
Westerly  Rl  02891. 


Atv 


Number  20  on  your  Feedback  card 


Ham  Television 


W4HTB  Repeater 

Hank  Cantell  W4HTB  of  Bowling 
Green,  Kentucky,  decided  \o  slir  up 
some  ATV  activlly  in  the  r^gbn  with 
an  ATV  repeater.  Me  obtained  permis- 
sion from  the  k)cal  TV  station  (chan- 
nel 40)  to  locate  the  repeater  at  their 
transmitter  sire  about  15  miles  north 
of  town  (700  feel  above  aveiage  ter- 
rain). With  his  antenna  at  the  ISO-toot 
level,  Hank's  repealer  provides  great 
coverage  ttiat  indudes  Glasgow,  Ken- 
tucky {about  30  miles  to  the  north* 
east). 

Features 

The  repealer  fias  both  in-t>and  and 
cfossband  capabilities.  The  input  is  on 
439.25  MHz  with  outpuls  on  both 
426.25  MHl  AM  TV  as  well  as  1280 
MHz  FM  TV  {5,8  MHz  audio). 

One  of  the  most  unusual  futures 
of  the  repeater  is  the  ability  to  transmit 
two  differenl  audio  channels  through 
Ihe  use  of  bolti  subcarner  and  on-car- 
rier sound  on  the  426.25  MHz  output. 
The  subcarrier  audio  channel  relays 
Ihe  rwrmal  ATV  audio  signal  while  Ifie 
on-carrier  channel  listens  to  the 
t44.34  MHz  FM  receiver  that's  locat- 
ed at  the  repeater  site.  Not  only  does 
the  system  work  as  an  ATV  repealer 


but  as  a  crossband  FM  voice  repealer 
as  weiii 

Touchtone  control  via  the  VHF  re- 
ceiver allows  the  users  to  turn  the 
426.25  MHz  outpul  Oft  SO  that  Ihe  sys- 
tem works  solely  as  a  crossband  TV 
repeater  to  allow  link  capabiliry  with 
dher  repeaters.  Hank  plans  to  install 
an  additional  receiver  on  42t^S  MHa 
10  allow  his  repeater  to  relay  \he  out- 
put of  the  KJ4ZO  ATV  repeater  In 
Nashville.  Tennessee  (50  miles  to  the 
soulhK 

Another  Touchtone  command  al- 
tows  the  user  to  turn  on  Ihe  repeater 
continuously  for  DX  contacts  (essen- 
tially links  the  receiver  directly  to  the 
tnar^mitter  without  the  need  for  sync 
trigger}. 

Additional  commands  wHI  turn  on 
the  video  ID,  switch  in  another  video 
source  or  a  five  shack  or  tower  cam- 
era. 

The  Hardware 

The  repeater  is  horizomtally  polar* 
ized  on  the  70  cm  band.  A  stacked  set 
of  "Quad  Uttle  Wheels'  by  Oide  An- 
tenna Labs  is  mounted  at  the  160-toot 
level  of  the  tower,  feeding  a  20Q-foot 
run  of  t  ■  hardline  to  the  equipment 
room.  The  signal  is  split  to  the  receiv- 


Phok>  8.  Tbe  component  parts  of  itie  W4HTB  repe^t&r  are  asseaitiBd  in  Hank's 
finai  test  ^diity. 


er  arvd  the  transmitter  using  a  TX-flX 
#2S-6S^l  A  duple Ker« 

The  receive  system  consists  of  a 
PC.  Electronics  ATVR-4  receiver  that 
deiiveis  video  to  the  video  switch  and 
sync  detector  circuit.  The  video  ID 
and  alternate  video  sources  can  be 
routed  through  the  video  switch  as 
well  (controlled  by  Touchtone  com* 
mands  via  Ihe  VHF  receiver).  In  addi- 
tion, the  426.25  MHz  transmitter  can 
be  controlled  by  Touchtones.  The 
video  signal  from  the  switcher  goes  to 
both  Ihe  426.25  MHz  AM-TV  transmit- 
ter and  the  1280  MHz  FM*TV  trans- 
mitter.  The  426  25  exciter  was  made 
by  Best  link  and  feeds  into  a  Pauldon 
18-watt  amplifier  (PD-440N)  and 
routes  back  into  the  duplej^er  The 
1280  MHz  FM'TV  transnRitler  is  a 
Wyman  Research  system  that  in- 
cludes an  exciter  Into  an  SC1043  am- 
plifier brick.  The  1280  MHz  antenna  is 
a  9  dB  gain  Diamond  vertical. 

Activity 

If  you're  In  the  Bowling  Green  area, 
try  giving  the  local  ATVers  a  call  on 
144.34  MHz.  They  usually  are  active 
every  evening  atler  about  3:30  p.m.  If 
you're  operating  mobile  TV,  the  re- 


peater is  located  right  next  to  1-65 
{ne&f  exit  39),  Some  of  the  more  ac- 
tive ATVers  in  the  region  are  Hank 
W4HTB.  Dean  K4NQV.  Fred 
KA4CFW,  Ben  W04MNI.  Bob 
KB4FEN,  Randy  KD4AMfl,  and  Paul 
K4VXP  (located  60  miles  away  In 
Gampbellsville). 

Night-Vision  R/C 

During  a  fecent  visit  to  the  W4HTB 
QTH,  Hank  treated  me  with  a  demon- 
stration of  his  night-vision  ATV  rover 
He  mounted  an  ATV  Iransmitter  and 
an  Infrared  sertsttive  CCD  camera  on 
a  USA'1  Monster  Tmck  R/C  car.  This 
vehicle  is  capable  of  traversing  in* 
credibly  difficult  ten'ain  due  to  its  four 
monster  balloon  tires.  The  camera  is 
offered  by  Marshall  Electronics  and 
has  six  high-intensity  infrared  LEDs 
mounted  around  the  lens,  allowing  the 
camera  to  see  about  15  leet  in  total 
darkness.  Hank  has  great  fun  driving 
the  vehicle  around  under  the  house 
as  well  as  venturing  out  in  the  woods 
at  night  looking  for  nocturnal  crea- 
tures. A  vehicle  lil^e  this  has  a  number 
of  interesting  applications  including 
potential  use  as  hazardous  emergen- 
cy  support. 


Photo  A.  Hank  Cantreil  W4HTB  working  fns  A*  r  repeater  from  his  ham  shack  in 
Bowling  Green,  Kentucky, 


ffholo  C,  The  W4HTB  night-vi^)n  R/C  vehtcie. 

73  Amateur  Radio  Today  •  July,  1 994  63 


Nurntwr  21  on  your  Fe^tiack  card 


^m  nurnwr  zt  on  your  re 

Above  &  beyond 


VHF  and  Above  Operation 


C.  L  Hmghlon  WBStGP 
San  Diego  Microwave  Group 
G345  Badger  Lake  A\^, 
San  Diego  C A  92119 

Frequency 

Last  month  we  discussed  convert- 
ing a  phase -locked  synthesizer/oscilla- 
tor for  2. XXX  GHz.  This  month  I  wilJ 
butid  on  last  month's  project  and  de- 
scribe In  detail  the  multiplier  the  filter, 
and  the  oscillator  drive  amplifier. 
These  componenis  serve  as  an  osdl- 
rator  mullEplier.  which  ccu^  be  used  in 
conjunction  wfth  a  10  GHz  converter. 
The  attempt  here  is  to  utilize  inexpen- 
sive surplus  components  and  PC 
boards  to  ftii  a  need,  ar>d  to  constaict 
a  converter  package  ttiat  is  smalt  and 
funcljonal.  and  doesn't  cost  an  arm 
and  a  leg  lo  diipllcate. 

Faliing  back  for  just  a  minute,  I 
would  like  lo  touch  base  on  the  syn- 
thesizer, in  particular  on  the  power 
supply  you  construct  to  power  these 
PC  boards.  These  devices  require  a 
vary  dean  DC  power  supply.  By  that  I 
mean  that  the  ripple  content  has  to  be 
quite  pure  or  else  you  will  have  modu- 
lation on  your  oscillator  caused  by  t^e 
AC  r^apie  component  ndmg  on  the  DC 
in  your  power  supply.  It  does  not  lake 


much  lo  cause  noise  or  FM  moduia- 
tion  on  the  synthesizer.  To  make  sure 
this  doesn't  happen  to  you*  filter  your 
DC  supply  well 

Pete  Bauer  W6DXJ,  who  has  done 
quite  a  tew  of  the  conversion  details 
on  the  synthesizer  unit,  recommends 
using  a  good  voltage  regulaiof  to 
maintain  DC  regulation.  AddilJonalty 
using  some  ferrite  beads  on  the  DC 
distribution  leads  at  the  oscillator  to 
suppress  AC  and  other  RF  will  prove 
useful  I  usuaFiy  bypass  the  output  of 
my  voltage  regulators  with  not  just  a 
suitable  electrolytic  cap.  but  with  a 
couple  ol  extra  bypass  types  (0.1  \if 
and  0.001  pF)  as  well,  to  cover  all 
bases  on  the  positive  lead.  See  Figure 
1  for  the  schematic  detail  oi  power 
supply  configu  ration. 

The  PC  boards  that  I  am  modifying 
here  ware  part  of  a  microwave  trans- 
mitter/receiver used  on  trucks  for  com- 
munication and  data,  As  such,  they 
were  built  quite  ruggedly  and,  need- 
less to  say,  are  solid-state,  with  GaAs- 
FETs  in  almost  all  of  the  circuitry.  This 
month  ril  describe  the  second  portion 
of  the  oscillator  system,  namely  the 
osciHator  multiplier  Please  note  that 
this  is  but  one  of  many  methods  used 
to  obtain  a  10  GHz  injection  for  10 


Ftgufe  I.  Power  supply  teed  details.  Basic  vottage  regviator  power  supply:  oufpiit 
capacitors  vary  in  value  70-0. 7-0,007  iiFfor  wtde-rarrge  bypass  Mering. 


Photo  A.  The  original  multiplier  PC  board— 2.620  GHz  In,  IJ,  1  GHz  output  This 
uses  fwo  Mitsubishi  GaMFETs,  MGF'13i^. 


GHz  operalion.  The  PC  boards  that 
are  described  here  are  bemg  made 
available;  you  ran  order  them  for  S10 
per  boaro  ppd  Irom  the  author. 

A  tsrief  descriplion  of  these  PC 
boards:  As  stock  they  were  made  to 
operate  at  2.620  GHz  (synthesizer), 
and  the  multiplier  was  a  times-five. 
providing  13.1  GHz  output  from  the 
set  of  PC  boards,  fii^ultiplication  was 
done  in  the  first  stage  of  the  second 
board  in  an  MGF-1302  GaAsF^  de- 
vice.  The  output  of  this  stage  was  cou- 
pled into  a  siripline  filter  resonant  at 
13.1  GHz  to  allow  bandpass  operaikjn 
of  the  desired  51  h  harmonic  and  re- 
duce alE  other  kequervcies.  The  filter 
output  is  coupled  with  a  small-value 
capacitor  lo  an  output  ainplifier  tuned 
to  13.1  GHz,  another  MGF'1302 
GaAsFET  device, 

In  the  original  system,  the  amplifier 
of  the  multiplier  assembly  was  fed  to  a 
distribution  ampHfier  system  on  a  third 
PC  board.  This  board  contained  an  in- 
put amplifier  and  power  splitter.  A 
power  splitter  is  a  strip  line  device  that 
looks  tike  a  tuning  fork  with  the  lop  ter- 
minated In  a  resistance  load.  Its  pur- 
pose 1$  to  split  the  signal  (one  source) 
into  two  equal  sources:  one  source  for 


Out  To 

TransmiL 


RF  IN 
13.1     GHz 


Out  To 

Receive 

hliKer 


S 


Figure  2.  Microwave  spfliler  amplifier  PC  board  diagram,  Note  the  local  oscillator  mixer  drive  ampiifiers.  this  PC  mard  uses 
four  MGF'1302  FBTs.  The  dual-st^ge  amp  has  been  cut  from  the  main  board  and  readjusted  to  10  GHz. 


receive  and  the  other  for  transmit.  Tvro 
additional  amplifiers  are  located  in  the 
Iransmrt  path,  and  there  ts  one  in  the 
receiver  path.  These  amplifiers  have 
been  removed  from  this  PC  board  by 
cutting  the  board  and  making  two  tO 
GHz  amplifiers,  a  two-stage  and  a  sin- 
gle-stage unit.  This  board  is  not  re- 
quired in  the  multiplier  modification, 
but  can  be  used  by  removing  the  sin- 
gle- and  dual-stage  amplifiers  and 
converting  Into  Individual  amplifiers. 
These  amps  can  be  used  at  10  GHz 
as  gain  bk>cks  with  siripline  srx>wf1ake 
retuning  from  13.1  GHz.  See  Rgure  2, 
the  sp fitter  tx>ard  btock  diagram. 

The  multiplier  PC  board  is  of  prime 
concern  now,  along  with  our  attempt  to 
modify  it  to  a  frequency  multiplication 
of  four,  fn  tt^is  regard  we  need  to  modi- 
fy the  output  circuit  of  the  fiis!  stage 
from  13.1  GHz  to  10.2  GHz.  The 
siripline  filler  was  tco  difficult  to  at* 
tempt  retuning  lo  10  GHz  A  better 
method  is  to  eliminate  the  siripline  fii* 
ter  by  removing  the  copper  foil  with  an 
X-Acto  knife.  Our  plan  here  is  to  re- 
place the  filter  with  another  type  of  fil- 
ter that  can  be  easily  constructed  and 
assembled — someihing  easier  than 
the  original  stiipHrte  filter.  The  answer 
to  this  problem  is  an  adjustable  cavity 
resonator  tuned  to  our  4th  harmonic. 

Where  do  you  find  Such  a  filter?  In 
the  plumbing  section  of  your  hardware 
store.  Whiai  we  used  is  a  1/2"  copper 
pipe  cap  plug.  Sounds  ciazy.  yes,  but 
it  worics  perfectly  and  is  easy  to  adjust. 
Credit  for  this  filter  construction  goes 
to  the  North  Texas  Microwave  Society 
for  passing  on  the  information  on  the 
filter  construction. 

The  copper  pipe  cap  works  quite 
well,  being  simple  to  construct  and  ad- 
just. A  finished  filter  will  have  about  1 
to  1.5  dG  loss  and  a  bandwidth  of 
about  50  to  100  MHz.  I  haven't  mea- 
sured Ihe  "0'  of  the  friter  but  believe  it 
10  be  atx>ut  IDO,  Essentially,  the  pipe 
cap  fitter  is  a  resoriani  cavity  with  two 
probes,  input  and  output. 

These  probes  are  copper  or  brass 
pins  about  0.030"  In  diameter  and 
3/1 6th'  long,  The  pins  are  inserted 
from  the  trace  side  of  the  PC  board 
through  to  the  foil  side  and  are  aboirl 
3/16"  high  on  the  foil  side.  They  are 


64  73  Amateur  Radio  Today  My,  WB4 


-Jli.S^ 


Ptioto  C,  The  top  of  me  PC  board  enclosure  for  the  maWpfier,  snowing  the  ppe 
cap  fitter  arxf  acf justing  scmw  poking  through  the  ltd  of  the  PC  hoard  case.  Coax 
connectors  for  input  output  and  DC  feed-through  capaaiors  have  been  add&d^ 


Photo  B.  The  modified  PC  iXMfd,  conver^ng  the  muftiplier  to  a  times  4.  Note  the 
ink  dfcie  mark  and  the  PC  strips  removed  from  the  fitter  area,  located  Just  aixfve 
tfie  circle  cut-out. 


soldered  to  the  mmamtng  erxJs  of  the 
oEd  fitter  strlpline  positioned  about 
1/16'  from  the  inside  wall  lor  the  pipe 
cap  when  it  is  soIderecJ  to  the  Jo i I  side 
Note  the  circle  drawn  for  the  pipe  cap 
positioning  on  the  fotf  side.  The 
stripline  that  remains  from  the  original 


slfipline  fnter  is  rraw  nothing  more  tlian 
50  ohm  stripline  which  feeds  the  two 
probes  of  the  pipe  cap  fitter.  You  will 
have  to  patch  the  PC  board  with  a  few 
small  scraps  of  copper  foil  or  solder 
bridge  ttie  traces  to  extend  the  new  50 
ohm  stripline  to  filter  probes.  See  Fig- 


ure 3  for  fitter  cor^truction  details.  Ex* 
act  compliance  is  not  necessary 

I  started  the  modification  on  the 
multiplier  board  t?y  removing  the  filter 
traces  on  the  PC  board  with  an  X-Aclo 
knife.  See  Photo  A.  Ihe  original  un- 
modified PC  board,  and  Photo  B,  the 
modified  PC  board.  As  you  can  see  in 
Photo  B,  (  drew  a  circte  representir>g 
where  the  pipe  cap  will  be  soldered  on 
the  opposite  side  of  the  PC  board,  and 
left  copper  traces  on  the  stripline  side 
to  solder  to  the  probes. 

The  bottom  of  the  PC  board 
(ground  side),  where  the  filler  probes 


are  to  be,  Is  reamed  away  to  give 
clearance  for  tf>e  brass  pjns-  This  pre- 
vents possible  gn^nding  of  (tie  pins. 
To  ertsure  this  and  to  give  them  a  rigid 
structure,  I  used  a  partian  of  Teflon 
from  3  scr^p  SMA  microwave  connec- 
tor to  stip  over  the  pins  for  positioning 
and  insuialJor).  If  you  don't  fiave  a  corv 
nector  to  scrap ,  use  the  pin  from  a 
DB-9  Of  06-25  connector,  as  Ihe  di- 
ameter is  just  right,  and  insulate.  II  you 
have  a  Tefion  insufator  or  tubing,  slide 
it  over  the  pin  to  make  the  pin  rigid 
and  hold  the  pin  vertical  arid  not 
grounded. 


ID-8  Automatic  Morse  Station  identifier 

Compatlbfe  with  Commefclal.  Public  Safety,  and  Amateur  Radio 
applications.  Uses  Include  Repeater  identifiers.  Base  Station  Identrfiers, 
Beacons,  CW  Memory  Keyers,  etc,  Great  for  RGC.  ID  Compliance. 

•  Miniature  In  &lze.  ^M''^^^^)n\}.!l^y, 

•  total ly  RF  immune 

■  All  connections  matfe  w\]h  mitrodiinlgture  plug  affd  sccfeet  wifti  ralor  ccided  wi?issaltaciied 

•  CMOSrnicraproces-soi  tor  \m  voltage,  lovw  cur  rent  ^^peFat'on   6tQi20VOC  unfeguflaEefi  al  5ma 
Low  dlsiortfDT^,  low  Impetianee.  adiustaDfe  sin^ave  outpui  [}  la  J  vons  peak  id  pean 
Cf^ial  conucjlled  lor  ti!gt>  accuracy. 

TTansinmef  prr  guEpul  tio  key  ifansmiti^f  while  ID  is  Wing  sem)  ts  an  open  ci3F|«H)r 
T!^n£i&tDr  thai  will  handle  3D  VHC  at  30Qma. 
?ield  aro^rammahle  wim  SU  PPL  I  to  KaytXHrd 

CqnlirmaiiQn  tone  To  mdicaie  accipted  WTArmv.  pkJS  Iwes  le  Imfhcate  pragoinming  ermr 
All  f3-togtaTvnin|i  *s  sic^d  in  a  rwn-volstile  tEf'ftOWl  wh<h  msy  tiE  aUsfic  at  ar^  time. 
Messa^  iengiti  over  ?Q0  clvaraciers  long 
'  i^ge^  ID  with  active  tiigh  or  icm, 

mm  ID  witti  active  fiigti  or  low  W^l  hojd  ofl  ID  umii  thafinei  is  ctear  of  tmfic 
Gene^ale^  rppoaie^  min&iiY  tsfii  al  end  d  u^f  tiansmssidfi  if  etiabted 
DvHitiie  siffid  iai>e  ^d  mauntHig  turdwara  supfiliKl  tor  qwcR  mauiilau}. 
qp^raiing  ternpsratuiv  range    -30  tiepttS  C  to  -f-GS  degrees  C 
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73  Amateur  RadfO  Today  July,  T994  65 


^^TH^        6/32    Brass   Screw 


r 


6/32    Nut 


Ground  Folf 


r 


Teflon 


PC  Board 


,i.\A.-j  t'^A  I  ■■--■J  -.  hfj  I  bVd"  I  'iVj-  ■  'aVj'i  WUUTh. 


3/16" 


W 


P/0    Stripline 


Brass   Pfns 


1/2"    Plumbing 
Brass  Pipe  Cap 


Solder 


^ 


Ground  Foi! 


PC  Board 


P/0    stripline 
From  Filter  Ends 


Figure  3.  Pipe  CBp  filter  construction  for  10  GHz  operation.  The  brass  pins  are  3/16"  long  inside  cavity.  Round  Tefipn  insuta- 
tor  1$  slipped  over  the  pins  to  hold  them  vertical  and  to  insulate  from  the  cavity  and  the  6-32  screw. 


Prepare  the  top  of  the  pipe  cap  by 
drilling  a  hole  in  the  top  center  of  the 
cap.  Tap  for  6/32  threads  and  solder  a 
brass  nut  over  the  hole.  I  used  a  steel 
screw  to  facilitate  this  operation,  as 
the  steel  screw/  will  not  take  solder 
welL  The  steel  screw  is  to  be  used  as 
a  centering  tool.  The  idea  here  is  that 
the  steel  wtii  resist  the  soldering  oper- 


ation  and  only  allow  the  nut  to  be  sol- 
dered to  the  top  of  the  pipe  cap  as- 
sembly (centered  on  the  hole  drilled 
for  the  6/32  screw).  After  the  solder 
cools,  the  steel  screw  can  be  removed 
from  the  cavity.  A  brass  6/32  screw 
with  a  nut  run  up  on  the  screw  is 
placed  into  the  cavity  top.  If  you  are 
not  sure  what  kind  of  screw  you  have. 


test  it  with  a  magnet.  I  am  sure  you 
will  identify  many  different  screws  that 
you  thought  were  steel  or  plated  steel 
and  you'll  find  that  they  are  nonmag- 
netic and  are  most  likely  plated  brass. 
Any  of  these  are  OK  to  use  for  cavity 
retuning.  See  Figure  3  and  Photo  C 
for  pipe  cap  cavily  details.  The  design 
is  rather  forgiving  In  the  positioning 


and  length  of  the  probes  and  frequen- 
cy resonance.  The  loss  of  the  filter 
and  coupling  will  be  affected  by  probe 
length.  I  find  about  3/16"  to  be  a  good 
choice  for  probe  length. 

When  soldering  the  cavity  (about 
and  Insutated  from  the  coupling  pins) 
To  the  PC  board  position,  (use  some 
iorm  of  sleeving  on  the  pins  to  ensure 
they  stand  straight  up  and  are  insulat- 
ed from  the  cavity  side  wall.  Be  ginger 
with  solder  in  this  application  and  try 
not  to  get  solder  inside  the  filler — it's 
very  lossy  at  microwave  levels.  Don't 
overheat  the  pipe  cap  as  components 
on  the  other  side  of  the  PC  board 
might  unsolder  wltft  too  much  heat. 
Tack-solder  the  cavity  to  the  ground  foil 
over  the  probes,  near  your  planned  ink 
line  drawn  on  the  opposite  side  of  the 
board.  An  exact  fit  is  not  necessary; 
just  center  the  6/32  screw  about  the 
center  of  the  probes  and  keep  the  cavi- 
ty side  wall  off  of  the  probes.  If  the  cav- 
ity wall  touches  the  Teflon,  that's  OK. 

As  you  can  see  from  Photo  B^  the 
finished  multiplier  assembly  I  made 
used  scrap  copper  PC  board  material 
to  fashion  a  case  for  the  multiplier  II 
also  made  it  quite  easy  to  attach  coax 
connectors  to  the  very  soft  Teflon  PC 
board.  This  gave  the  board  a  rigid  feel 
that  made  modifications  and  opera- 
tions easier  on  the  workbench,  During 
the  re -adjustment  step  of  modification 
I  found  that  most  of  the  gain  improve- 
ments to  the  circuit  were  made  on  the 


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66  73  Amateur  Radio  Today  *  July,  1 994 


muftipJier  stage.  Initially.  I  connected 
aljoul  +5  dB  ®  2.55S  GH^  lo  the  mul- 
tiplier input  and  tried  to  observe  output 
at  tO.5  GH2,  the  Mh  multiple.  I  ctieat- 
ed  arid  used  a  t>encti  oscillator  for  this 
reluning  !esl  and  ixri  the  modified  syn- 
fiestzer  (versatjiity  and  test  contiD^K 

I  connected  a  power  meter  to  the 
oytput  and  found  almost  notfilng  for 
power  out  (less  Ihan  -20  dBm).  I  start- 
ed to  tune  the  pipe  cap  fiTler  (inserting 
Ihe  screw  tnio  cavity),  and  as  I  did  the 
power  irxjf eased.  I  tuned  the  tiller  for 
the  best  power  output  I  could  obtain 
and  it  was  at>out  a  -6  dBm.  I  took  a 
took  on  the  spectrum  analyzer  and 
found  out  that  the  freqttency  was  what 
I  wanted,  and  further  identified  that  the 
f titer  would  only  tune  to  the  fourth  har- 
monic^  nrtaklng  the  conversion  of  the 
filter  quite  easy.  In  other  words,  I  was 
quite  Jucky.  With  this  in  mtnd,  I  am 
quite  confident  that  you  will  not  need  a 
spectnjm  analyzer  lo  make  modifica- 
tions as  only  a  microwave  power  me- 
ter Is  needed. 

To  bring  the  power  up  1  applied  the 
standard  *'snow1lake"  copper  tuning 
tools  to  the  PC  t>oand  lo  find  hot  spots. 
Fof  those  not  familiar  with  tuning  mi- 
crowave circuitry  and  "snowf taking,*  I 
am  referring  to  using  bits  of  copper 
maler^al  to  be  moved  about  the  RF 
portkxis  of  crrcuit  boa^  to  retune  the 
CirctiiLry.  Instead  of  moving  tjits  Of  cop- 
per about  the  board  much  like  a 
shuffle tx>ard,  constaict  some  loots  \o 


do  the  job  tor  you.  The  tuning  tools  are 
made  by  super-gtumg  small  bils  of 
copper  foil  to  toothpicks.  I  used  rour>d 
tooihpicks  and  cut  off  one  end  to 
make  a  slight  flat  spot  to  sdhere  the 
copper  bit  1o^  Make  several  of  various^ 
sized  copper  bits.  I  started  off  by  get- 
ting some  ooppef  foil  (from  bobby  or 
modef  railroad  stx)f}s}  and  cutting  it  in* 
to  miniature  pieces  about  0.050  to 
0.100  square — the  exact  size  is  not 
importanr  E  usitaliy  close  my  eyes  and 
chop  up  a  small  piece  of  copper  foil 
and  then  seEeci  what  I  want  from  the 
cutoffs.  Some  of  these  bits  wili  be  at- 
tached to  toothpicks,  and  the  others 
will  da  soldered  on  the  PC  board 
traces,  duplicating  the  size  and  posi- 
tion that  the  toothpick  "snowflake''  test 
produced. 

When  moving  the  tools  about  the 
PC  boardp  keep  the  DC  power  on  and 
be  careful  not  to  short  anything  out- 
go slow.  Remember  to  turn  off 
DC  power  when  you  soJder  copper 
bits  lo  the  trace,  with  a  duplicate  bit 
of  copper  as  indicated  by  the  tuning 
tool,  on  a  hot  spot.  These  hot  spots 
found  in  the  *'snowflake  test"  are 
places  where  you  either  add  or  re- 
move copper  from  the  existing  Irace.  If 
by  coming  near  a  trace  the  power  re- 
duces, this  mighl  indicate  that  you 
need  to  remove  copper  foil  or  modify 
the  trace  at  this  point.  El's  like  the  drop 
in  power  is  saying^  "I  don't  want  any 
more  copper  circuitry  (in  the  form  of 


traces) ^  but  l  want  less,  so  remove 
some  (copper  foil}.'  In  some  cases  the 
width  of  a  PC  board  trace  need  be  re- 
duced. 

When  making  any  changes,  do  it  in 
a  slow  methodical  manner  ar>d  do  rrot 
make  large  changes;  go  slow — a  few 
thousarxJths  at  a  time — and  check  for 
chartge.  The  rule  is:  wide  traces,  very 
low  impedance:  narrow  traces,  very 
high  impedance.  A  50  ohm  trace  on 
this  type  of  PC  board  is  about  0.035' 
wide  or  so.  My  hedge  on  this  Is  that  I 
don't  Icnow  the  exact  dielectric  con- 
stant for  the  materfal  lo  cak:ulale  il  ex* 
actfy.  so  this  is  an  estimate.  As  an  ex* 
ample.  100  ohms  =  0.015%  and  20 
ohms  =  0.100"  wide. 

If,  on  the  other  hand,  power  In- 
creases when  the  area  is  approached 
by  moving  the  toothpick  with  a  copper 
bit  attached,  add  copper  to  this  area. 
Be  careful  to  not  short  out  traces  with 
the  copper  bits  as  DC  power  is  on 
when  you  are  testing  with  the  tooth- 
piclc  tools.  When  you  add  or  remove 
traces  to  the  board,  turn  off  the  power 
and  use  a  static-free  work  station  and 
grounded  soldering  iron,  A  tempera- 
ture-controlled iron  is  the  best  iron  to 
use.  They  operate  from  low  voltage 
DC  and  are  usually  grounded.  Static 
and  high  voltage  soldering  irons  can 
produce  enough  voltage  to  zap  a  sen- 
sitive GaAsFET  device.  To  minimize 
static  a!  my  work  station,  I  connect  a 
groutnd  wire  frnm  my  iron's  ground  to 


the  work  piece,  a  copper  circuit  t>oard 
that  serves  as  a  common  grounded 
work  station.  Don't  forget  the  wrist 
Strap  with  a  bufJt-in  high  resisiance 
discharge  path.  The  high  resistance  is 
there  for  your  protection,  as  well  as  lor 
static  elimination.  Ground  Ihe  PC 
board  with  a  dip  lead  to  Ihe  common 
wofKpiece,  Everything  at  common 
ground  should  eliminate  any  static 
problems. 

In  hindsight.  I  found  that  most  of 
the  gain  improvements  were  rnade  in 
the  multiplier  stage  of  the  PC  board,  I 
obtained  a  +7  dBm  output  at  10.220 
GH2  by  using  a  drive  source  at  2.555 
GHz.  No  retuning  was  necessary  in 
the  13.1  GHz  stage  to  obtain  this  re* 
suit.  More  power  or  better  efficiency 
could  be  obtained  by  retuning  the  13.1 
GHz  stage.  I  just  stopped  the  modilk 
cation  without  retuning  this  Stage  as 
+7  dBm  power  was  all  that  was  need- 
ed for  E  good  mixer  Injection  level,  If 
you  want  to  re-tune  the  multipfier's 
amplifier  go  about  it  in  the  same  n^n- 
ner  as  the  multiplier  stage. 

Well  that  s  il  for  this  month.  As  al- 
ways. I  will  be  glad  lo  answer  ques- 
tions about  this  topic  and  related  ma- 
terial Please  Send  an  SAS£  for  a 
prompt  repJy.  Next  month  I  will  cover  a 
surptus  Loran  receiver  that  can  be 
computer-operated  to  give  you  Lat- 
tong  positions  and  convert  them  to 
six 'figure  grid  squares  for  grid-square 
hopping.  73  Chuck  WB61GP 


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73  Amateur  Radio  Today*  July,  1 994  67 


Ask  haboom 


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Your  Tech  Answer  Man 


MtcfmeiJ.  G^er 
c/o  73  Magazine 
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Pmefttorougti  NH  0345$ 

Getting  Clipped 

Radio  as  we  know  it  today  is  an 
analog  medium.  Oh,  sure,  there's  lots 
of  digjia!  control,  and  some  digital  sig- 
nal processors  have  begun  to  appear. 
Still  In  the  end  w©  mod ui ate  a  carrier 
of  some  sort  with  some  kind  of  analog 
informalton.  even  when  we  actually 
want  to  send  digital  data.  The  possible 
exception  is  CW,  aithoiEgh  that's  de- 
batable. But  what  exactly  separates 
the  digital  and  anaFog  universes,  end 
what  happens  when  you  push  them 
beyond  their  limits?  Let's  take  a  look 
at  some  of  the  ways,  both  analog  and 
digital,  to  represent  irifonr^ation.  and 
then  e^amtne  the  consequences  of 
overdnving,  of  ^clipping,'  thenrL 

Squash 

Ju$t  what  Is  cfipping?  WelL  imagine 
yoy're  a  dfOjit  of  some  kind.  You  have 
limits,  beyond  which  you  just  can*t 
give  any  more.  Along  comes  this  sig* 


nat  which  is  so  strong  yott  canT  haodte 
it  an.  Sa.  you  give  as  much  as  possi- 
ble and.  when  the  s^nal  goes  out  of 
bounds,  you  just  stay  at  your  output 
voltage  jimi!  unlrl  it  comes  back  within 
your  rarige.  II  we  now  graph  your  out- 
put or  look  at  it  on  an  oscilloscope,  the 
highest  and  lowest  points  will  be 
squashed  flat,  or  clipped.  That's  seri- 
ous distortion,  and  it  has  differing  con- 
sequences, depending  on  what's  be- 
ing clipped, 

In  an  analog  system,  information  is 
represented  by  a  changing  signai 
which  in  some  way  mimics  what  you 
want  lo  send.  There  are  various  ways 
to  do  that  and  each  behaves  different- 
ly under  clipping.  Let's  iook  at  a  few. 

Baseband 

You  may  have  heaid  this  term  used 
to  describe  many  kinds  of  signals.  But. 
underneath  an  the  definitk)ris,  such  as 
video*  data  or  audio,  lies  a  common 
C^jncepl.  Baseband  refers  to  tiie  or>gi~ 
nal  modulating  signal,  before  it  ^  im- 
pressed on  something  else.  So,  in  a 
stereo  system,  bastard  audio  is  just 
plain  audio.  In  other  words,  it  is  not 
digitized.  FMed,  or  whatever-ed.  In 


video.  It  refers  to  the  vtdeo  signal  as  it 
comes  from  the  cameran  VCR  or  other 
video  source.  Especially  in  video, 
where  RF  modulators  are  common, 
the  term  reaiiy  helps  lo  keep  things 
straight:  ts  this  switch  handling  base- 
barxi  or  RF?  In  radio ^  baset>and  refers 
to  the  signal  you  wish  to  send,  or  the 
one  you've  received  alter  demoduLa- 
ttorv 

Sometimes,  though,  the  definition 
can  get  murky,  Lefs  say  you  receive 
an  SSTV  signal  on  20  meters.  Out  oi 
your  speaker  come  the  warbling  tones 
which  represent  a  picture.  Are  they 
baseband?  Well,  as  far  as  the  radio  is 
concerned,  they  are.  because  they  are 
demodulated  audio.  But,  SSTV  is  sent 
as  FM.  meaning  that  the  frequency  of 
the  warbling  tones  Js  proportional  to 
the  [nstantaneous  brightness  to  be 
displayed  on  the  TV  screen.  So^  we 
don't  really  get  to  baseband  video  until 
the  SSTV  converter's  FM  circuits  de- 
mod  ui  ate  the  tones  into  a  varying  volt* 
age  representing  the  picture  elements. 
That  voftage  fs  truly  the  ""b as e band" 
video  signal  aibeit  slowed  down  Even 
more  confusingly,  the  time -con  verted 
video  signal  actually  sent  to  the  TV 
monitor  is  also  baseband  video  fast- 
scan  video. 

When  yoo  clip  a  baseband  signal, 
its  lops  and  botloms  get  flattened. 
With  audio,  it  sounds  like  tremendous 
distortion.  With  video,  it  disturbs  the 
sync  pulses,  which  are  at  the  bottom 
of  the  signal,  arxJ  it  turns  high -bright- 


ness points,  such  as  facial  h^hlights, 
to  white.  The  sync  disturbar>ce  can  re- 
sutt  in  wiggly  pictures  which  tear  and 
roll  as  the  scene  changes.  ATVers  of- 
ten have  to  wrestle  with  this  problem, 
because  ft  is  hanj  to  make  RF  transmit 
amplifiers  which  stay  completely  linear 
frofTi  edge  to  edge. 

AM 

This  ts  one  of  the  easiest  modes, 
yel  still  one  of  the  most  complex.  The 
modulating  signal  changes  the 
strength  of  the  earner.  Seems  simple, 
right?  At  first,  thai  appeared  ali  there 
was  to  it.  After  a  short  time,  It  became 
dear  that  much  more  was  going  on. 
The  concept  of  sidebands,  in  which 
the  modulation  appears  in  mirror  im- 
ages on  either  side  of  the  carrier's  fre- 
quency, was  not  immediately  believed. 
It  took  quite  a  bit  of  mathernaticaf  de- 
velopment, and  significant  measure- 
ment and  obsen/ation,  before  the  side- 
band theory  was  accepted.  Even  now, 
you  can  hear  debates  as  to  exactly 
how  much  power  is  going  into  the 
skfebands  and  how  much  into  the  car- 
rier, which  is  presumed  not  to  actually 
change  strength,  despite  how  it  looks 
onaso^pa! 

Clipping  an  AM  signal  has  drastic 
consequences.  The  amount  the  side- 
bands spread  from  the  carrier  de- 
pends on  the  nnodulating  frequencies. 
When  we  clip,  though,  the  rale  of 
change  of  the  earner  at  the  moment  of 
dipping  becomes  very  high,  implying  a 


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68  73  Amateur  Radio  Today  July,  1 994 


much  higher  modtiratiorr  frequency 
Ihan  is  actually  present.  That  resutts  in 
all  kinds  of  sidebands  very  far  from  the 
carrier,  which  we  call  "splatter"  li*s  a 
mesSp  both  spectrally  and  legally. 

SSB 

Sideband,  which  Is  a  special  form 
of  AM.  suffers  from  the  same  prob- 
lems when  overdriven.  But  how  oan 
we  ciip  a  carrier  when  there  isr^'t  one? 
Well,  remem&er  thai  we  are  generat- 
ing an  RF  sigraal  ar>d  then  making  rt 
cancel  ttselt  out  in  the  modulator.  The 
object  3s  to  create  sidebands,  one  of 
which  we  then  throw  away  and  the 
olher  of  which  we  send  on  to  the  an- 
tenna. If  we  clip  the  modulator,  It  gen- 
erates the  same  kinds  of  false  sid^ 
bands  we'd  get  with  AM,  and  we  wirxJ 
up  sending  those  on  one  side  Of 
course,  the  sideband  filter  will  keep 
the  extia-wide  ones  in  check,  But^  if 
Uie  clipping  occurs  in  the  final  ampli- 
fiers, the  mess  makes  tt  to  the  anten- 
na because  it  happens  after  the  side- 
band filter. 

FM 

Is  it  possible  to  dip  an  FM  transmit- 
ler?  [n  theory*  no.  After  air,  we're  just 
higgling  a  carrier's  frequency  back 
and  forth,  so  there  should  be  no  limit 
as  tc  how  wide  we  make  rt.  in  practice, 
though,  the  drcuit  stages  have  t>and- 
width  limits.  When  we  deviate  the  sig- 
nal far  enough  to  run  into  those,  ihey 
will  begin  to  cut  the  signal  off  as  it  ap- 


proaches the  outside  points.  The  re- 
sult is  an  *AM-ing*  of  the  signal  as  its 
strength  goes  up  and  down,  along  with 
AM-iike  splatter  arid  distortion. 

The  FM  receiver  is  a  special  case. 
Its  cfipping  points  are  set  by  the  IF 
bandwidth  and,  especialty,  the  detec- 
tor bandwidth.  If  the  transmitted  signal 
ejfceeds  the  IF  bandwidth,  it'll  get  AM- 
ed  just  like  it  would  in  the  Iransmitter 
example.  If  the  signal  exceeds  the  lin- 
ear bandwidth  of  the  detector,  it'll  dip 
the  audio  just  as  it  It  were  an  overdriv- 
en t^aseband  amplifier. 


with  nice,  flat  ends.  Of  course,  ifs  a 
kind  of  serious  distortion,  t>ut  does  rt 
matter? 

Not  In  this  case.  Remember,  with 
FM  the  information  Is  in  the  wiggling  of 
the  carrier's  frequency,  not  in  any  am- 
plitude changes.  That  frequency  will 
survive  the  dipping  process  Just  fine. 
In  fact,  it'll  be  the  only  thing  left,  whtch 
is  just  what  we  want- 
By  the  way,  that  njshing  noise  you 
hear  when  there's  no  signal  on  an  FM 
receiver  is  caused  by  the  same  pro- 
cess; the  small  amount  of  internally 


"Baseband  refers  to  the 

original  modulating  signal, 

before  it  is  impressed  on 

something  else. " 


There's  one  place,  though,  where 
clipping  is  deliberately  empEoyed  In  an 
FIVI  receiver  in  order  to  reduce  sus* 
ceptibllity  to  impyise  noise  and  other 
amplitude  phenomena.  In  fact,  this 
kiFKl  of  clipping  is  what  is  responsible 
for  FM's  inherent  superiority  to  AM  in 
that  respect. 

The  basic  technique  Is  to  posh  tfre 
IF  ampHfiers  beyond  their  linear  limits, 
forcing  them  to  dip.  That  flattens  any 
noise  spikes  or  other  changes  in  am- 
piitude  riding  on  the  received  carrier. 
What's  left  is  just  the  carrier  signal. 


generated  noise  in  all  circuits  is  ampli- 
fied by  the  dipper  (also  called  the  "llm- 
IteO  to  the  point  where  it  wings  from 
rail  to  rail  (the  upper  and  iower  limits) 
and  is  detected  as  random  noise. 

Inter  mod 

Tntermod  is  caused  by  clipping, 
usually  in  the  front  erxl  of  a  receiver. 
The  overloading  signals  cause  Ihe 
front ^end  ampiifier  to  distort,  creating 
all  kinds  of  sidebands  of  its  own. 
Those  then  look  like  phantom  signals. 
Aiso.  clipping  causes  mixing  of  other- 


wise-unrelated signals,  causing  odd 
blends  of  them  all  over  the  dial.  And, 
when  a  very  strong  foreign  signal  is 
present  at  a  transmit  antenna,  inter- 
mod  can  occur  in  ihe  final  amplifier  of 
the  transmitter,  making  it  broadcast 
the  mess  all  over  town,  or  even  all 
over  the  wo  rid.  If  you  don't  believe  me, 
ask  any  urtian  repeater  owner. 

Well,  t  hope  you've  enioyed  getling 
clipped  in  the  analog  domain.  Next 
time,  we'll  take  a  kiok  at  wfiat  happens 
wlien  signals  clip  in  digital  circuits. 
Now.  let's  look  at  a  letter: 

Dear  Kaboom, 

I  have  two  mobile  2  meter  rigs. 
With  a  strong  signai,  they're  both  fine. 
But.  when  I  listen  to  a  weak  signaL  the 
older  one  always  seems  to  pick  up  lots 
of  ignition  noise,  white  the  newer  one 
doesn't  hear  it,  even  when  I  use  the 
same  antenna.  Is  the  slaticky  one  bro- 
ken, or  can  I  adjust  it  somehow? 

Signed, 
Headache  #12 

Dear  Headache, 

What  a  relevant  letter  for  this 
month's  discussionl  No,  neither  of 
your  hgs  is  brok^.  and  there's  r>oth- 
ing  you  can  adjust.  The  quieter  receiv- 
er has  better-designed  IF  clipping 
stages,  so  it  rejecls  more  AM,  which  is 
what  ignition  noise  spikes  appear  to 
the  rig  to  be.  Tm  afraid  you're  stuck 
with  it. 

Until  next  time.  73  de  KBIUM. 


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73 AmBfeur  Radio  Today*  July,  1994  69 


Number  24  on  your  Feedback  card 


^^p  ^^  Number  m  on  your  heeoDai 

73  INTERNATIONAL 


Amie  Johnson  NIB  AC 
43  Old  Homestead  Hwy. 
N.Swan^ey  NH  Q3431 

Notes  from  FN42 


Before  t  started  the  column  this 
month,  1  just  had  to  reread  the  report 
from  the  Peter  i  DXpedition  written  by 
Peter  ON6TT.  He  has  such  a  great 
sense  of  humor  spread  throughout  the 
report-  i  just  wish  that  we  had  the 
space  to  print  it  alt. 

Another  MothQfs  Day  approaches 
as  t  sm  working  on  this  column,  which 
means  that  HosstraderE  is  just  a  few 
days  away  (the  Friday/Saturday  of 
Mother's  Day  weskenO).  it  is  another 
^'great  happening'  similar  to  Dayton 
and  others,  but  mostty  taitgating  out- 
of-doors. 

There  is  much  forafi—onB  person's 
junii  is  another's  treasure,  it  is  reaify 
something  to  just  sit  back  and  watch 
the  smiiing  faces  go  by  iuggtng  a  'boat 
arTchor"  from  days  past-  You've  proba- 
bly seen  that  same  boat  anchor  go  by 
during  past  Hosstrader's.  too,  if  you 
matty  kept  track 

t've  already  be^n  given  my  ''march- 
ing orders"  from  headquarters  (my 
XYL):  "No  new  stuff  unless  you  get  rid 
of  some  of  the  old  stuff ^  She's  said  ft 
in  the  past,  and  this  time  she  really 
means  it!  If  you  saw  some  guy  crying 
as  tiB  unloaded  some  of  his  "trea- 
sures' at  bargain  pric^,  tl  was  proba- 
bly meL  I  hope  that  you  were  one  of 
the  lucky  ones  to  get  or^e  of  my  trea- 
sures.' 73  'tit  next  month. — Arnie 
NIBAC 

Roundup 

Brazil  From  the  WWSA  News — 
Jart/Feb  1994:  The  Bfazilfan  magazine 


Antenna-Bectronica  Popu/ar  invites  all 
amateurs  worldwide  to  participate  in 
the  13th  edition  of  the  well-known 
WWSA  CW  Contest, 

The  contest  is  hefd  on  the  second 
fufl  weekend  in  June  (June  11-12, 
1994]  staning  on  Saturday  al  1500 
UTC  and  lasting  until  Sunday  at  1500 
UTC.  A  separate  log  for  each  worked 
band  must  be  sent  no  Jaier  than  July 
31  to:  WWSA  Contest  Committee,  PO 
Box  2S2.  ZIP  20001-970,  Rjo  de 
Janeiro.  RJ -Brazil 

Germany  From  the  Deufscher  Am- 
ateur Radio  Club  (DARC):  How  to  Ap* 
pfy  For  a  German  Short-Tenn  Air^ateur 
Radio  Licence:  Licenced  foreign  ama- 
teurs staying  temporarily  in  Germany 
(on  visit  or  in  transit)  may  obtain  a 
shoft'temi  amateur  mdio  flee  nee  from 
the  Deutsche  Bundespost.  valid  tor  a 
period  of  three  months,  by  directing 
their  application,  at  least  six  weeks  in 
advance,  via  Deutscher  Amateur  Ra- 
dio Club,  tniernattona!  Affairs.  Post- 
tach  11  55.  W  '  3507  Baurtatal  1.  Ger- 
many to  Oberpost^rektion  Dussetdorf . 
Licence  fee  ar>d  handling  costs  for  a 
three-months'  ficence  amount  to 
0M15  {deutsche  marks).  This  sum 
should  be  iransferred,  at  the  same 
time  as  the  appilcation  Is  sent,  in  Ger- 
man currency  (no  IRCs.  no  stamps 
please)  by  postal  money  order  to; 
Postscneckkonto  (postal  cheque  ac* 
count),  no.  56  13-430  at  Postscheck- 
aml  Essen.  BLZ  360  100  43,  for 
DARC — Iniernational  Affairs — w — 
3507Baunata[1. 

A  German  licence  will  only  be 
granted  if  the  applicant  possesses  a 
valid  amateur  radio  licence  of  his  na- 
tional administration  which  is  at  least 
equivalent  to  the  German  licence 
class  requested 


in  the  application,  the  following 
should  be  given:  1)  Nationality  of  ap- 
plicant; 2)  FifSt  name  and  sumame;  3) 
Date  and  place  of  birth;  4)  Home  ad- 
dress; 5)  Home  catlsign.  class  of  li- 
cence; 6)  The  three  months'  period  re- 
quested; 7)  Address  of  location  of  op- 
eration; 8)  Address  to  which  the  li- 
cence document  Is  to  be  sent;  9)  Con- 
firmation that  the  licence  fee  has  been 
forwarded  to  the  Postscheckamt  Es- 
sen (photostat  of  payment  slip):  10) 
Photostat  of  your  hoit^e  amateur  radio 
licence,  together  with  an  indication  of 
the  date  of  issue  and  duration  of  valid- 
Sty,  class  and  comparable  German 
class  of  licence  (Class  C— 144  &  430 
MHz  only:  Class  B— All  HF  band  fre- 
quencies and  144  &  430  MHz;  Class 
A— 3520-3700.  21090-21150.  28000- 
29700  kHz,  144  &  430  MHz.);  11) 
MerBtMrship  in  a  national  amateur  ra- 
dio society  (yes/no),  and  the  name  of 
the  society.  German  short-term  ama- 
teur radio  licences  are  issued  to  for- 
eign amateurs  for  periods  of  three 
months  only,  beginning  on  the  first  day 
of  the  month,  as  requested  by  the  ap- 
plicant The  shoft-term  licence  will  en- 
IJUe  the  foreign  amateur  to  operate  a 
Fixed,  mobile,  or  portable  amateur  sta- 

Peter  t  Info  from  Peter  0N6TT,  Eu- 
ropean Coordinator 3Y0Pt:  There  was 
excellent  propagation  during  the  first 
days  of  the  operation.  Europe  was 
coming  in  fairly  weak  during  the  first 
weel^.  which  was  of  major  concern  to 
us.  Propagation  was  very  unpre- 
dictable. Sometimes  we  could  wofk 
EU  on  20m,  from  0400  on.  while  the 
r>ext  day  we  couki  rot  hear  them  at  aJt 
during  the  EU-moming.  Sometimes 
40m  to  EU  opened  up  at  0000,  some- 
limes  as  i ale  as  0600.  During  the  sec* 
ond  week  (excluding  the  weekend,  un- 
fortunately),  signals  from  EU  were  fair- 
ly strong,  but  it  Seemed  that  despite  2 
kW  and  yagls.  EU  could  not  receive  us 
very  well. 


30m  was  a  disaster.  TT>e  band  was 
alrrm^t  completely  covered  with  South 
American  SSB  pirates.  On  40m  and 
90m  we  had  problems  attracting  EUs* 
attention,  especially  in  SSB.  We  woukl 
hear  very  strong  signals,  but  could  not 
get  anyone  to  answer  us  Jn  that  case, 
we  answered  somebody's  "CQ  DX" 
(most  of  tt^  time  he  would  not  believe 
it  was  us  answering  his  call)  and 
asked  hfm  to  look  for  a  frequency 
ciear  for  us  to  transmit  on.  Normally, 
this  worked.  Reception  on  the  low 
bands  was  very  good,  though  {no 
man-made  noises).  We  had  only  one 
good  opening  to  EU  on  1 60m. 

After  one  day  of  operation,  we 
found  that  stateside  would  cover  up  all 
EU  signals,  so  we  favoured  EU  from 
the  moment  we  could  hear  them. 
Sometimes,  we  tried  10  work  very 
weak  EU-signals,  leaving  9+30  USA 
people  waitJr^  for  a  while.  Neverthe- 
less, we  could  not  leave  any  continent 
waiting  for  too  long  a  time,  so  some- 
times it  could  happen  that  you  would 
hear  us  wiih  weaker  signals  working 
the  USA^  and  not  working  Europe. 
And  believe  me.  this  was  not  easy  We 
held  statistics  on  what  continents  were 
worked  on  what  bands  and  modes,  so 
we  would  give  everybody  an  equal 
chance  for  as  many  band  modes  as 
possible. 

Uving  conditions:  We  had  two  oper* 
atlng  shelters  of  8  x  8  ft.  (one  CW  and 
one  SSB),  a  kitchen  shelter  of  8  x  12 
ft,  (used  lo  sleepH  awaiting  evaouation 
of  the  island),  and  a  sleeping  shelter 
of  12  X  24  ft.  Shelters  were  wamied 
with  propane  heaters  (siic  boltfes  of 
100  kg  propane  each).  Our  separate 
top-open  toilet  shelter  with  a  home- 
made toitel  seat  proved  to  be  very 
useful  (but  we  had  to  count  on  digging 
out  five  feet  of  snow  before  'taking  a 
sit^. 

Power:  Two  4  kW  Onans  and  two  5 
kW  HcmdaSn  with  14  barreis  of  gaso- 
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I  Amateur  HF  Transceivers 

VHF'UHF  Transceivers 

HT's  and  Mobiles 

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73  Amateur  Radio  Today  *  July»  1 994  71 


Onaris  fose  parts  like  bolls,  nuts,  muf- 
flers and  pilots.  As  long  as  they  Keep 
on  vlbraling  on  tfieir  wooden  crate- 
cover  basas,  wtiile  trying  to  mate  with 
the  Honda  nescl  to  them,  mey  tend  to 
ke^p  on  woridng. 

Antennas:  15.  20-  and  40m  mono- 
yagis:  10-15-2Q  tnbanders,  12-17-30 
tribander  HF  verticals,  wire  antennas, 
and  70cm/2m  yagis  for  saiellUe. 

Radios:  Nine  Kenwood  rigs  of  vari- 
ous kinds  (four  died  during  the  opera- 
tion); four  Alpha  amps,  which  ran 
beautifulJy  without  a  hiccup.  Various 
satellite  and  RTTY  gear  was  QRT  up- 
on arrival  (rough  handling)  or  went 
QRT  shortly  thereafter 

Cornpulers:  For  various  reasons* 
computers  were  only  used  tor  RTTY» 
and  by  one  op  for  loggir>g.  Atier  five 
days  we  were  Eetl  with  on}y  one  work- 
ing computer  power  supply,  Most  of 
the  logging  was  done  on  paper.  Yes, 
you  can  run  RTTY  pileups.  even  if  the 
only  way  to  switch  between  trar^smit 
and  receive  is  t>y  resetting  ihe  mo- 
de in. 

Luckily,  all  people  Involved  (hams 
from  the  London  area.  Falklands,  Pun- 
ta  Arena,  locals  from  Fatklands,  the 
Antarctic  bases  and  South  America) 
were  very  helpful;  we  were  well  pre- 
pared (shelters,  clothing,  transporta- 
tion) and  had  extensive  Spare  equip- 
ment: we  had  the  pilot  stations  (thank 
you  John  ON4UN  and  Mark  0N4WW 
fdr  the  super  job  as  the  European  pi- 
totst)  to  keep  us  linked  to  the  DX  com- 
munity, to  our  homes,  ar>d  to  all  kinds 
Of  people  involved  in  this  operation 
(trans portation.  manufacturers,  etc,). 
Both  of  you  pyt  m  so  miich  time,  effort, 
and  quality  in  your  tasks  that  it  ia  diffi- 
cult to  Ihank  you  enough;  as  opera- 
tors, we  were  very  motivated  to  bring 
this  challenge  to  a  good  end.  I  think  it 
was  this  motivation  that  got  us 
through. 

It  is  really  difficult  to  describe  all  of 
the  non  radio  stuff  involved  in  such  an 
operation.  Come  to  one  of  the  upcom- 
ing presentations  and  you  wilt  under- 
stand. One  thir^:  We  were  not  conv 
plaining  about  the  hardship  we  went 
through.  On  the  contrary,  all  o(  us  are 
proud,  y^Pi  proud  of  wtiat  we  did. 


p  wish  (hBt  t  could  have  printed  the 
complete  report  from  Peter  ONSTT  ft 
has  a  gerjutne  humor  that  makes  easy 
fBading  and  makes  certam  humorous 
pomts  about  the  ftving  corKittions  en- 
dured to  bnrrg  the  rest  of  us  amtacts 
from  one  of  the  "rare  ones. "  Thank  you 
att  for  a  job  welt  done! — Amie} 

MONACO 

Danlef  Pfett  3A2LZ 
8.R  349 
MC  98007 

Greetings  to  all  from  Monaco.  This 
has  been  a  father  quiet  spring  here  In 
the  Principality — not  too  much  unusual 
going  on.  The  Association  des  Radio- 
Arrtateufs  de  Monaco  had  its  annuaJ 
meeting.  The  first  order  of  business 
was  the  election  of  the  council  tor  this 
year.  Most  of  the  council  membeis  re- 
mained the  same.  The  only  change 
was  at  Ihe  positron  of  General  Secre- 
tary. Ciayde  Passet  3A2LF,  who  has 
worked  hard  at  that  position  for  a  num- 
ber of  years.  Is  taking  a  year  off. 
Serge  Safganik  3A2HM  is  filling  the 
position  for  this  year 

A  number  of  projects  are  in  the 
works,  Last  year,  some  of  the  local 
hams  were  asked  at  the  last  minute  to 
help  the  l^/lonaco  Red  Cross  during  the 
Monaco  Grand  Prix.  They  apparently 
liked  the  help  and  have  asked  us  to 
help  again  this  year. 

A  foxhunt/direction- finding  compeH* 
tion  is  planned  for  June  1 9, 

The  Monaco  repeater  is  about  the 
only  repeater  botuccn  the  Italian  bor- 
der and  Nice.  France.  The  mountains 
further  complicate  VHF  communica- 
tions  in  Ihe  area.  The  Monaco  re* 
peater  has  an  unusual  split  though 
which  cannot  be  accommodated  with 
many  2  meter  rigs.  One  of  our  projects 
is  to  modify  it  to  work  on  a  normal 
split. 

There  Is  no  further  news  on  the  6 
meter  situation.  6  meter  activity  in 
Monaco  and  the  nearby  part  of  Frarkce 
is  still  prohibited. 

Finally.  iiYRL  was  fegafly  active 
from  Monaco  the  beginning  of  April, 
especially  on  30  meters.  Congratula- 
tions if  you  worked  fiim. 

Let  me  remind  you  again  that  the 


Monaco  QSL  bureau  can  only  be  used 
for  members  of  the  A.R.M.  We  receive 
a  numtief  of  QSLs  for  nonmembers, 
and  this  causes  problems.  And,  the 
onty  correct  address  for  the  A  R.M,  Is 
Box  2.  Monaco-  A  number  of  other  ad- 
dresses appear  in  various  DX  publica- 
tions but  are  inconect. 

Best  73  from  Monaco.  Daniel 
3A2LZ. 

PHILIPPINES 

Lorenzo  a  Gaston  DU1CHD/6 

P.  O.  Box  27 

6116  Silay  City 

Neg.  Occ. 

Philippines 

First,  thanks  (or  the  many  letters 
from  the  readers  of  this  column,  I  en- 
joy answering  my  mail  but  can't  afford 
to  answer  letters  wiihoul  an  S.A,S.E.  I 
already  have  a  lot  of  BURG  QSLs  to 
answer  for  IOTA  OC-129.  and  also 
many  direct  cards  without  S.A.S.E.S, 
which  J  have  no  choice  but  to  return 
via  BUBO. 

This  month  I  decided  to  bring  our 
readers  up  to  date  with  the  additional 
guidelines  for  the  renewal  of  an  ama- 
teur radio  license  and  application  for 
amateur  radio  examination. 

I.  Renewal  of  Licenses:  1)  Before 
an  Amateur  Radio  License  or  Opera- 
tor's PennH  is  renewed,  the  applicant 
must  show  proof  of  his/her  involve- 
ment  in  amateur  radio  activities.  An 
Amateur  Radio  Ucer^e  hokfer  may  be 
involved  in  any  of  the  following:  a) 
DX— He/she  must  tje  abie  to  present 
Log  Extracts  and/or  QSL  cards.  DX 
Awards  earned  as  a  result  of  hla^^er 
DX  activities;  b)  TechnicaJ  Btpehmen- 
tafion — He/she  must  show  proof  of  be- 
ing involved  in  the  lachnlcal  aspects  of 
the  hobby,  which  may  include  propa- 
gation tests  and  exploration,  electronic 
innovations  (such  as  the  improvement 
of  present  equipment  and  acces- 
sories), home-brewing  of  equipment 
and  accessories.  These  must  be  prop- 
eriy  documented  with  the  submission 
of  test  results,  drawings  and  circuit  di- 
agrams where  necessary;  c)  Emer- 
gency Communications— He/she  must 
show  proof  of  hkaving  been  involved  in 
purely  Amateur  Emergerx;y  Communi- 


cations and,  in  the  case  of  an  emer* 
gency  or  disaster  situation,  participa- 
tion  ar>d  active  membership  in  tfie  Anv 
ateur  Radio  Emergency  Service 
(ARES)  will  suffice:  d)  Active  member* 
Ship  in  an  Amateur  Radio  Clut>— An 
amateur  radio  enthustast  can  only 
grow  and  progress  in  his/her  hobby 
ttirough  an  exchange  of  ideas  and  the 
support  of  his/her  fellow  amateurs. 
Membership  in  an  NTC  recognized 
Amateur  Radio  Club  therefore  is  vital 
and  Important.  This  is  optional  but 
highly  encouraged;  e)  Field  Expedi- 
tion— This  amateur  activity  is  highly 
encouraged  lor  radio  amateurs,  A 
group  can  conduct  a  field  expedition 
by  securing  for  a  permit  from  the  Com- 
mission (NTC)  and  a  corresponding 
Special  DX  caiisign  will  be  assigned 
for  the  purpose. 

2)  The  proof  of  Amateur  activity  wilt 
come  in  a  form  to  be  submitted  by  the 
appiicani  with  his/her  application  for 
renewal  (Form  ARSCP-001).  This 
form  must  be  endorsed  by  a  local 
club,  duly  recognized  by  the  NTC  as 
an  Amateur  Radio  Club  or  a  Class  "A* 
Amateur  Radio  license  holder,  The  ap- 
plicant need  not  be  a  member  of  the 
ciub  where  the  endorsement  was  ob- 
tained from,  but  the  club  or  Class  "A' 
endorser  shall  be  held  responsible  for 
such  endorsement  of  the  applicant 

IL  Applicant  for  Amateur  Radio  Ex- 
amination: 1)  An  applicant  for  the 
Class  "C"  or  "D*  amaleur  radio  exami* 
nation  is  required  to  attend  an  ohenta- 
ten  seminar  conducted  by  an  autho* 
rized  radio  club  or  a  Class  "A'  amateur 
license  holder  with  comesponding  en- 
dorsement E>efore  ha^she  is  allowed  to 
take  the  corresponding  examination; 
2)  The  authority  of  an  amateur  club  or 
Class  "A'  amateur  license  holder  to 
hold  seminars  and  endorse  exami- 
nees can  only  be  Issued  by  the  Ama- 
teur Radio  Consultative  PaneL  The 
authority  given  to  an  amateur  dub  or  a 
Class  "A"  Amateur  license  holder  shall 
be  for  a  period  of  one  year  only  (re- 
newable) unless  sooner  suspended, 
canceled,  or  revoked  for  failure  to 
comply  with  the  standards  and  agree- 
ment set-forth  by  the  Amateur  Radio 
ConsuHative  Panel, 


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72  73  Amateur  Radio  Today  •  July,  1 994 


A 


DVERTISERS 


•  A.aA , , ,70 

•  A.S.A 84 

351  Absolute  Value  Systems. „....14 

164  Ace  Communications  of 

Indfianapoiis ...-....., .„.„..*.,,»41 

•  Advanced  Elect ronic  Applications  ..9' 
149  Advantage  insirurnents 

'Wjrpovo.iion .............  >^.^ ,.. »,  »i  .1  »iHM«  tttt » 1 J 

231  Agreto  Engineering _».„„ ...J© 

194  Ail  Electronics  Corporation  ....,,^.^3B 

»    Alphaiab... „ _.M 

76  Amateur  Networking  Supply  .,„..«.,  17 

•  Ampire,  Inc 14 

1 1 3  Amsoft 53 

336  Anlennss  west  f,,,.^.^.,,^^,*,^*,^ *r***^js 

332  Antennas  West «* 7t 

107  Antennas  West „ „„„.,73 

363  Antennas  West .83 

132  Antennas  West _„e4 

296  Antennas  West »,. ...BS 

135  Antennas  West 68 

69  Antennas  West 87 

•  Antique  Radio  Classified ..32 

80  Arrow  Antenna........,,, ., 71 

t6  Astron  Corporaiton,.,, 23 

•  Azden  Corporation 43 

21  BAB,  Inc .,71 

41  Barry  Qectronics  Corporation 21 


»■- ■!■«>■■■■  ■■**'■#■■■« 


42  BMl  Oompan/ 

137  Sox  Produces 
56  Buckmasier  Publishing 
7   BucHmaster  Publistiing 

168  Suckmasier  Publishing 

•  Bu  rgtiardt  A  mat  eu  r  Ha  d  i  o 

•  Bulternul  Electfonics 

222  Byers  Chassis  Kits 


■  ■  +-k  +  -t-l  ■■  +  +  +  ■■  I 


PPP'P-i  +  FFIIi   l  +  FPqq   I   I 


.14 

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29 

26 

32 


134  C  5;  S  Sates,  fnc ...71 


•  CABLE  X-PERTS.  INC ..........14 

239  Cam  Lazercut  Signs ., «,.. J6 

•  CB  City  internationaL.,.. .«»84 

265  Chipswiteh , ,„,„,.8S 

186  Coaxial  Dynamics ,.........„....80 

99  COfnmunlcalion  Concepts.  Inc 56 

10  Communication  Spedalists.  Inc 65 

356  Communications  Oedronics,  Ina  .25 

181  Digital  Communicatjons 54 

13  Doppter  Systems ...,. „ «...6S 

•  Down  East  M  icro wa ve . , . ., 64 

114  E.  H.  Yosl 72 

8  E[ktronics 65 

•  EUR-AM  Efectronics 17 

33  FB  Enterprises ,,.,62 

£31  rEyieuran ^....+^^».,,,,,.,,o/ 

118  FlyteCrafl .73 

329  For  Hams  Only. _.....,..„... 32 

•  Gap  Antenna  Products . 83 


193  GGTH 


---  ■'«-<l--f<-P-P^  T^TTT^gB  ■  ■< ■>*<-* Jfii-frHh  i-ftbii  I  »->§•*■■-■ 


14* 


338  GiObal  Upgrades 85 

230  Grove  Enterprises ., .47 

286  Hambrew  Magazine „ .51 

•  Ham  Radio  &  More 33 

73  Hamsure » ...».» 32 

•  Hamtronics,  Inc .„,„,7 

345  Ham  Windows... M 

187  Harlan  Technologies ^ 14 

355  Harrington  Software T7 


87  High  Sierra 


B-ll'V-P"»1¥VVVI'>^b4i|BI>l1-VI-ll-l-V-F'«-l 


,43 


43  Highlands  Electronics. „„ ....,.,53 

293  \C  Engineering.... , 32 

179  icom,,.. CV2' 


263  innotek,  Ire.. 17 

^'b'       ■  k?  V  ^  I    K/*   I    ■i-4^l-li^d--hl!liiFl   l-lll4fl-lll-ri++llrii-l    illl++FBil>  +  +  +  U^T 
V-^      V      V|J Wi   t  I      .i.  k  |.  L  J  H  4' h  f  ■  i  d  *+ F  ■  1  ^  +  +  -*-  I  i  i  +■>■  i  i  i  I  t't  I  I  I +  +  4' B  I  i1  ■■■I't'^     ' 


R.S.#  page 

228  Jade  Products 85 

133  Jade  Products .49 

240  Jan  Crystals 26 

159  Japan  Radio , ...2 

•     K-Comm..... ............................. ...70 


2  Kawa  ProduclJons..„™ 32 

151  KOC  Sound... 87 

•  Kefwood  USA  Cofporatioo CV4 

197  Lathrop  Publicatioiis,  Inc 66 

234  Lentinj Communications.. 77 

230  Maggiore  Electronics  Lab... „J6 

•  MCM  Electronics , 60A 

66  MFJ  Enterprises.......... ,. 11 

86  IVIFJ  Enterprises .59 

160  Micro  Computer  Concepts.... 53 

144  Micro  Control  Specialities  ... 81 

114  Mr.  Nicad , 72 

243  MoTron  Electronics „„ 31 

223  National  Anvaleur  Racfio 86 

54  HCG , ..» 5 

1  t^lumber  One  Syslenis  Ltd  «., 68 

•  0.F.3-  Wealherfax ...........«86 

102  ONV  Safety  Belt... 72 

172  OptoeJectronEcs ..45 

•  PC.  Electronics 62' 

•  PC.  Etectronics ,.. ..63' 

32 1  Patcomm 31 

63  Periphex , .57 

196  Persorel  Computer  Repeater 

Controller.-,..... — ,  ..■,„..■■■ ...^.-Tl 

•  Personal  Database  — 51 

249  Phillips  InduStnes,  Inc.. , X 

3 1 1  P  f  oneer  H  il^  Sot  tware , ... JST 

49  Poly  Phaser. ....69 

257  Quorum  Communications.,.. 27 

153  Hadio City... ..,».i...i.3D 

58  Radio  Engineers ,..17 


R-S-#  page 

•  Radio  Fun 73 

'     RAI  Enterprises 71 

34  Ramsey  Eiectronics 19* 

254  Ross  Distributing............... ............85 

•  RT  Systems ,. 17 

•  SAMS „ .17 

36  Scrambftng  News.... ...^ 

167  Sesoom,  Inc. .72 

...39 


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250  Software  Systems ...67 

244  Software  Systems ....43 

69  Spectrum  Electronics ...,5f 

183  Spectrum  International....... .83 


•  Ten-Tec „. ,37 

124  TeJtas  Bug  Catclier  Antenna ..„.„. .87 

•  The  Ham  Center . . ..70 

384  The  Ham  Contact ^^~. 78 

384  The  Ham  Contact... ...57 

269  Tigertronics ...............74 

374  TNR 77 

11  Transet  Technologies 87 

22  Tri-Ex 69 

32  UniveTsat  Electronics .56 

•  Universal  Radio .70* 

«    Vanguard  t-abs. 49 

259  Versatel  Commurtications 84 

276  Virginia  Beach  Hamfe$L............74 

104  Vis  Study  Guides.  Inc .....28 

191  W  &  W  Assocates  „. «75 

20  Wolfe  Communications ..„.83 

•  Yaesu  Etectro  nics  Corporation . ,  ,CV3 
268  Zero  Surge.  Inc ..,.<-. 49 

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73  Amateur  Radio  Today  •  July,  1994  73 


Never  Say  Die 

Continued  from  page  4 

gram  like  this  and  I've  missed  ft, 
please  let  me  Know. 

It  allowed  me  to  enter  the  monttiiy 
sales  figures  for  up  to  10  years  of 
sales  and  would  display  them.  Then  I 
could  asit  it  to  do  a  graph  dt  the  Tigiires 
and  it  would  give  me  max  and  min 
numbers  and  ask  what  max  and  min  I 
preferred  for  the  graph.  Once  I  typed 
those  In  it  would  present  the  graph, 
showing  the  sales  for  the  10 -year  peri- 
od. Okay,  we  probably  have  prograrrs 
today  that'll  do  that  much.  The  r^exl 
s^  was  to  ask  it  lo  do  a  moving  aver- 
age of  sales.  ]t  wouEd  ask  over  what 
period.  Id  leil  it  12  months.  It  would 
consider  that  for  a  minute  and  give  me 
a  chart  of  the  numbers.  Then  I'd  graph 
the  moving  average.  These  graphs  and 
charts  could  be  easily  printed,  just  by 
hiuifig  a  key  combinatimi. 

Now  we  come  to  Ihe  more  vatuable 
part,  ft  eouid  calculate  the  second 
deri>ratlve  of  the  sales  figures,  showing 
the  acceleration  or  deceleration  of 
sales.  I  found  that  the  number  of  pages 
of  ads  tn  73  and  in  QST  both  had  a  cu- 
rious 18- month  sine  curve  that  contin- 
ued for  years.  Even  more  valuable  was 
the  ability  of  the  program  lo  project 
sales  into  tlie  future,  based  on  trends 
and  taking  into  consideration  periodic 
changes,  such  as  seasonal  sales 
changes.  Is  there  anything  out  there 
that  can  do  this?  I'll  buy  Itl 

We're  not  talking  Einstein  here.  The 


math  required  fdr  ali  this  is  relatively 
simple,  ifs  }ust  that  no  one  has  both* 
ered  to  buikj  this  irito  a  program  for  the 
last  15  years.  Phooey.  Instead  they've 
been  busy  providing  us  with  three-di- 
mensional graphs  and  junk  like  that. 
Hey,  guys,  keep  it  simple! 

So  what  happened  to  Instant  Soft- 
ware? it  was  a  good  idea  and  it  d(d 
fairly  welt,  but  when  I  sold  my  comput- 
er magazines  to  IDG,  they  didn't  want 
to  be  bothered  with  mass-produced 
software.  And  without  the  infrastructure 
provided  by  the  magazines,  It  coutdnl 
continue.  6ut  we  learned  a  lot  and  had 
tons  of  fun  doing  rL 

For  instance,  we  learned  not  to  try 
to  sell  educationai  software  to  schools. 
We  wondered  why  some  o(  our  prize - 
winning  stuff  was  selling  so  poorly. 
When  we  studied  oyr  sales  we  found 
that  we  were  selling  one  copy  to  each 
school  and  they  were  makJng  all  fur- 
Iher  needed  copies.  A  couple  years  lat- 
er we  did  ar>other  study  and  found  that 
by  [hen  we  were  selling  one  copy  to 
each  school  district  S  talked  with  sev- 
eral other  software  companies  and 
found  they  had  the  same  experierce. 
That's  when  educational  software 
stopped  being  produced.  And  that's 
one  reason  we  still  don't  have  much  of 
it  thafs  any  good. 

At  o<ir  peak  In  tB^  we  had  around 
a  hundred  people  employed,  were  sup- 
porting over  250  good  programs,  were 
expanding  rapidly  into  Europe  and 
considering  opening  an  Irish  plant. 
Then  IDG  pufled  the  plug. 


Let  me  know  if  you  ever  see  a  good 
business  analysis  program  for  the 
Mac. 

Ahh,  the  Mac.  I  went  out  to  Cuperti- 
no for  the  unveiling  of  the  original  Mac. 
There  was  tremendous  hoopla^  but  I 
wasn't  impressed.  The  IBM  PC  had 
come  on  the  market  the  year  before 
and  it  almost  instaniiy  wiped  oul  the 
TRS'80  Up  until  I  hen  the  microconv 
pulef  market  was  split  with  Radio 
Shack  having  40%  of  sales,  Apple  an- 
other 40%  (Apple  II),  and  about  200 
smaller  companies  sharing  the  other 
20%.  Old-timers  will  remember  Com- 
puPro.  Morrow,  Ohio  Scientific.  Mtd- 
west  Scientific,  and  a  bur\ch  more, 

Apple  was  sami-lriendly  to  third-par- 
ty supporting  businesses,  but  Radio 
Shack  was  hostile.  Really  hostile.  So 
when  IBM  came  along,  they  had  no 
problem  in  capturing  most  of  the  third- 
party  support  from  Radio  Shack,  and 
that  quickly  collapsed  Radio  Shack 
sales.  They  went.  In  alKHJt  one  year, 
from  40%  ol  the  nnarket  to  atjoul  4%. 
and  have  never  really  recovered.  The 
chairman.  John  Roach,  never  forgave 
me  for  predicting  that  this  would  hap- 
pen unless  they  changed  their  policy  of 
fighting  third-party  support.  But  did  he 
leam  from  this?  Har-de-har.  So  Radio 
Shack  has  beert  a  very  minor  player 
ever  since  and  Radio  Shack  lost  bil- 
lk>ns  in  potential  sales.  Tens  of  bitlions. 
My  view  is  that  they  could  have  pre- 
vented the  IBM  putsch,  if  they  hadnt 
been  so  blinded  by  their  own  greed. 

The  Mac?  It  didn't  really  got  any- 


where unin  desktop  publishing  came 
along.  The  Mac  has  stayed  a  year  of 
two  ahead  of  the  PC  in  that  field,  and 
that's  been  Us  main  strength.  The  Mac 
PowerBook  was  a  major  step  ahead 
for  writers  like  me.  Td  tried  several  PC- 
type  laptop  computers,  but  none  of 
them  were  as  easy  to  use  as  my  old 
Radio  Shack  TRS-eo  Model  100, 
which  I  thought  Lhe  day  it  came  out  in 
1983,  That  went  everywhere  in  the 
world  with  me- 

Last  year  i  was  about  to  start  a 
PowerBook  magazine  when  I  saw  the 
trouble  coming  for  Apple  as  a  result  of 
Scully's  ego-fascination  with  the  New- 
ion.  That  got  him  frred.  whidi  was  wen- 
deserved,  I  thought  But  his  rep^ce- 
ment  seemed  weak,  so  I  was  afraid 
that  Apple  would  be  rudderless.  And 
that's  about  the  way  things  have  tumed 
out.  My  decision  to  not  start  the  Power- 
Book  magazine  last  year  has  proven  to 
be  prescient. 

Souly.  swept  up  in  hts  visions  of  the 
information  superhighway,  jumped 
without  looking  very  carefully  to  anoth* 
er  firm,  which  turned  oul  to  be  built 
mostly  on  vapor,  which  is  a  common 
er^ough  foundatian  in  the  computer 
field.  So  Scully  is  joining  the  parade  of 
has-beens  in  the  field  .  .  .  like  Jobs» 
Tramiel,  Busey  (Tl).  OeCastro  (Data 
General),  Olson  {DEC),  and  An  Wang, 

Oh,  you  probabty  donl  care  about 
all  that  okJ  stuff  anyway  I  just  can'X  help 
remembering  how  interesting  it  was  in 
the  early  microcomputer  days.  I  really 
should  write  about  them  some  time. 


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74   73  Amateur  Radio  Today  •  July,  1 994 


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Cold  Fusion  VaMdationt 

The  Fopufar  Science  article  Tast  Au- 
gust saying  that  cold  fusion  had  been 
given  a  premature  buriaf  by  some  pow- 
erful vested  interests  almost  got  nie  to 
thinking.  Like  many  others,  I'd  been 
excited  over  the  prospects  cold  fusion 
offered  wtien  Pons  and  FleEschmann 
announced  the  break-through  3n  1989. 
Then  the  whole  idea  was  trashed  tjy 
some  vocal  scientists,  who  were  given 
the  usual  extensive  media  coverage 
providing  bad  news. 

Then  I  read  in  the  Rensselaer  Re- 
view that  students  had  confirmed  the 
generation  of  excess  heat  as  reported 
by  Pons  and  Fleischmann.  This  was 
followed  by  two  books  bJastfng  cold  fu- 
sion as  a  hoax.  What  in  heck  is  going 
on  here? 

Next  I  heard  from  a  73  reader  who 
was  deeply  involved  in  the  cold  fusion 
field.  He  assured  me  that  the  effect 
was  quite  real,  despite  the  naysayers. 
He  started  sending  me  information 
confirming  that  researchers  world- 
wide had  successfully  duplicated  the 
early  experiments  and  were  busy  de- 
velopmg  the  technology.  He  convinced 
me  that  there  was  a  need  for  a  maga- 
zJne  to  hefp  this  new  technoEogy  grow 
Ento  an  industry.  It  didn't  take  a  lot  of 
convincing. 

I'd  seen  the  power  of  a  magazine 
when  I  decided  to  try  and  puti  amateur 
radio  out  of  its  deep  decline  following 
the  catastrophic  ARRL  reli censing  ef- 
fort in  1964^  when  our  growth  went 
from  11%  per  year  to  around  a  3% 


hi 


PHV^iBIt  le^SUE   «  WMk«SHJQEb«llW«rrv4ljyh 


COLD  FUSION 


JS 


a^rv^^mj  ij 


h:10; 


MIL 


III..      IW.HHa     lll.l^ll 


negative  growth.  We  needed  some- 
tNng  new  to  get  the  hobby  going  again 
and  2  meter  FM  and  repeaters  seemed 
like  the  ticket. 

So  I  began  publishing  hundreds  of 
articles  on  the  subject  in  73.  Then  I 
started  the  Repeater  Bufletm,  to  further 
push  the  technology.  That  was  fol- 
lowed by  a  series  of  books  and  re- 
peater atlases.  It  was  the  Chicago 
hams  who  developed  the  celiufar  ap- 
proach for  their  repeater  system.  Once 
I  saw  that  I  knew  that  ft  wouldn't  be 
long  before  this  service  would  be  made 
available  to  the  general  public. 

Within  a  couple  of  years  we  went 
from  having  isolated  repeaters  put  up 
by  pioneers  to  a  nationwide  network.  J 
foynd  myself  able  to  make  repeater- 


^:■i.'^5.;-¥■^ii^•f.:^^I■^ 

COLD 

BISION 


assisted  phons  calls  while  I  was  on 
skis  in  Vermont,  almost  anywhere  in 
New  Hampshire,  and  even  from  the  ski 
slopes  In  Aspen!  Sure  enough.  GE  and 
Motorola  grasped  the  significance  of 
what  we*d  developed  and  cellular  tele- 
phones were  born. 

Personal  Computers 

It  was  my  success  with  repeaters 
that  got  me  to  thinking  about  the  criti- 
cal importance  of  a  pubil cation  to  help 
new  technologies  develop  into  tndus- 
trtes.  The  articles  1  published  in  TJand 
the  Repeater  BuUelm  had  helped  the 
pioneers  speed  up  their  research  by 
providing  the  needed  communications. 
Further,  my  publications  attracted  the 
interest  of  more  pioneers  and  helped 


bring  them  up  to  speed.  And  lastly, 
they  made  it  possible  for  entrepreneurs 
to  go  into  business  supplying  the  pio- 
neers, building  an  industry. 

Within  three  years  repeaters  had 
become  the  largest  single  interest  in 
amateur  radio  and  built  a  $tOO-milllon 
new  ham  industry.  I  particularly  en- 
joyed that  because  the  first  react bn  of 
the  73  readers  was  to  complain  bitterly 
about  my  publishing  so  many  repeater 
articles.  \  got  hundreds  of  letters 
threatening  to  cancel  subscriptions  if  I 
didn't  cut  It  out.  Then  gradually  I  began 
to  get  letters  saying,  hey,  this  stuff  is 
lun  .  .  .  thanks.  At  the  time  I  was  the 
only  ham  publisher  covering  this  new 
technology,  so  I  felt  that  73  deserved 
most  of  the  credit  for  what  resulted. 

When,  in  January  1 975^  the  first  mi- 
crocomputer was  announced,  I  saw  the 
significance  of  the  technology  and  de- 
cided  it  was  time  to  see  if  1  could  do  it 
again,  I  started  trying  to  find  an  editor 
who  understood  computers.  For 
months  I  chased  after  the  editors  of 
computer  hobbyist  newsletters  to  see  if 
they  might  be  interested  in  working 
with  me.  Finally,  in  May,  I  found  a  chap 
In  Boston  who  had  been  publishing  a 
hobbyist  newsletter  with  about  200  cir- 
culation. He  was  game  to  give  tt  a  try. 

I  set  to  work  getting  articles  from 
ham  authors  who'd  been  submitting 
computer-oriented  material  to  73.  I  got 
the  names  and  addresses  of  anyone 
who  d  ever  written  to  the  suppliers  of 
parts  for  computers.  Some  of  them, 
like  Bill  Godbout,  had  been  advertising 


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73  Amateur  Radio  Today  'July,  1994   75 


quite  successfully  in  73,  t  got  shoe 
box 03  fill!  of  names  from  these  com- 
panies aad  sent  out  subscription  of- 
fers. The  response  was  incredible. 
Most  direct  mail  is  considered  a  suc- 
cess if  one  percent  of  the  potential 
customers  buy.  1  was  getting  20% I 

The  first  issue  of  Byte  came  out  in 
August  1975  and  looked  pretty  good 
as  a  starter.  The  73  editoriaU  and  pro- 
duction staff  had  done  most  of  the 
work.  It  was  lust  five  weeks  from  the 
lime  we'd  decided  to  start  Ihe  maga- 
zine until  the  first  issue  went  on  the 
presses!  I  decided  to  visit  the  prospec- 
tive advertisers  personally,  so  I  made 
a  trip  to  Albuquerque  to  talk  with  Ed 
Roberts,  who  started  it  all  with  his 
MITS  8800  Altalr  microcomputer.  I  al- 
so visited  Sphere  in  Salt  Lake  City,  a 
computer  game  group  in  Phoenix,  and 
Southwest  Tec hn real  Products  in  San 
Antonio,  bringing  copies  of  the  first  Is- 
sue with  me.  I  also  stopped  by  to  say 
hello  to  my  old  friend  Ed  Juge,  a  73 
advertiser  who  owned  a  ham  slore  in 
Fort  Worth.  I  gave  him  a  copy  of  Byie 
and  warned  him  that  microcomputers 
would  turn  Into  a  huge  industry.  Ed 
had  managed  to  survive  the  'Incentive 
Lk^ensirtg*  holocaust,  but  by  1975  was 
ready  to  give  up  trying  to  run  his  store. 

Later  1  found  that  he'd  gotten  so  ex- 
cited over  the  magazine  Td  left  tfiat  he 
bought  an  MITS  Altair  and  hQ6  be* 
come  addicted.  When  Radio  Shack 
got  into  the  business  with  their  TRS-80 
Model  1  In  td?7.  Ed  got  one  and  smart- 
ed programming  IL  In  fact,  when  I 


went  Into  t^e  business  of  selling  soft* 
ware  in  1978,  two  of  my  first  program 
releases  had  been  written  by  Ed.  The 
next  thing  I  knew  Ed  was  working  for 
Radio  Shack.  He's  still  there. 

Between  Syfe,  Kilobaud,  Microcom- 
puUng.  BO  Mk^Q,  Desktop  Computing. 
InCiden  and  a  few  of  my  other  publica- 
tions, plus  dozens  of  booKs  and  hun- 
dreds of  software  programs,  the  per- 
sonal computer  industry  grew  rapidly. 
By  1 982  Byte  was  the  largest  con* 
sumer  magazrne  m  the  country  and 
my  80  Micro  was  the  third  largest. 
Vogue  beat  rt  our  for  second  place. 

Compact  Discs 

When  the  compact  disc  was  intro- 
duced to  America  In  1982  1  decided 
there  was  a  need  for  a  magazine  to 
help  this  new  technology  grow.  I  start- 
ed work  on  this  in  1983  and  within  a 
couple  years  It  had  become  the  most 
influential  music  magazine  in  the 
country.  CDs  became  the  fastest  grow- 
ing consumer  industry  in  history. 

When  Sony  came  out  with  Smm 
video  I  tried  to  interest  them  in  a  sup- 
porting magazine.  J  was  unable  to  gel 
any  cooperation  from  Iham.  They 
didn't  see  the  Importance  and  refused 
to  talk  about  it  I  wonder  how  big  that 
mdustry  might  be  today  if  Sony  hadn't 
been  run  by  marketing  people  with 
btirxJers, 

Cold  Fusion 

Considerrng  the  strength  of  the  op- 
ponents of  co^d  fusion,  mosUy  made 


up  of  scientists  getting  billions  of  dol- 
lars to  try  and  develop  hot  fusion,  and 
rjghtfylly  afraid  that  cold  fusion  might 
drairi  some  research  dollars  .  -  *  of 
even  put  them  out  of  bysiness  . . .  get* 
ting  a  supporting  magazine  started 
looked  like  an  uphiiF  Job.  Worse,  since 
everything  was  stiti  m  the  research 
phase,  there  were  few  potential  adver- 
tisers. 

As  I  kx>ked  Into  the  situation  I  found 
that  while  labs  around  the  workj  were 
reporting  success  in  generating  unex^ 
plainable  heat,  no  one  had  a  theory 
that  explained  what  was  being  report- 
ed. Researchers  were  empirically  try< 
ing  this  and  that.  They  needed  better 
communications. 

The  prestige  science  magazines  re- 
fused to  publish  anything  about  the 
field.  Since  what  was  being  reported 
was  'Impossible,"  therefore  every  sci- 
entist involved  had  been  making 
stupid  mistakes  or  else  lying  about 
their  data.  This  mindset  controlled  the 
Department  Of  Energy  (DOE),  and 
even  the  US  Patent  Office,  where  cold 
fusion  was  classed  as  being  as  impos- 
sible as  perpetual  motion. 

Pons  and  Reischmann  were  so  up* 
set  over  ail  this  that  they  left  the  coun- 
try. The  Japanese  quickly  took  advan- 
tage of  the  situatiort,  Toyota  ap- 
proached Pons  and  Fleischmann  and 
offered  to  set  them  up  with  a  dream 
laboratory  on  the  Frer>ch  Riviera  .  .  . 
where  they  are  making  great  progress 
with  their  research. 

J  decided  to  go  ahead  wtth  a  pubft- 


cation.  I  announced  It  at  the  Fourth 
Cold  Fusion  Conference  on  Maui  in 
December.  My  editor  was  Dr.  Eugene 
Maltove,  the  auttior  of  Fire  From  fee, 
the  only  even-handed  book  on  cold  fu- 
sion. At  the  conference  I  listened  to 
hundreds  of  papers  reporting  the 
progress  in  the  field  arKJ  had  an  oppor* 
tunrty  to  meet  the  scientists  involved. 
Yes,  including  Pons  and  Fleischmann, 
W  was  an  exciting  confer enca. 

Upon  returning  to  New  Hampshire 
we  started  working  on  iCo/cf  Fusion" 
magazine.  We  put  the  title  in  quotation 
marks  because  no  one  yet  has  a  good 
theory  of  where  the  enormous 
amounts  of  iieat  being  generated  are 
coming  from.  The  first  issue  was 
mailed  in  April,  dated  f^ay  on  the  cov- 
er. I  didn't  need  any  Jokes  about  it  be- 
ing an  April  Foot  magazine. 

Ln  late  March  the  BBC  and  CBC 
(Canadian)  broadcast  welU researched 
documentaries  on  cold  fusion.  They 
gave  time  to  the  naysayers,  but  they 
left  no  doubt  that  the  phenomenon 
was  quite  real  and  probably  the  most 
important  scientific  discovery  of  the 
century. 

This  was  followed  by  the  May  issue 
of  MiTs  Technology  Review,  which 
had  a  cover  feature  on  cold  fusion, 
complete  with  an  tii)age  article  by  Dr. 
Ed  Storms,  who  was  our  cover  scien- 
tist for  the  first  issue  of  ICoW  Fusion. ' 
so  things  were  beginning  to  break. 
Just  to  give  you  art  idea  of  how  posf* 
tjve  this  article  was.  let  me  give  some 
quotes. 


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Wayne  is  mad  as  hetl ... 
...and  he  doesn't  wantjati 
to  take  it  anvmore! 

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Fed  up  with  the  mes  in  Washington? 

The  mess  Id  your  state  capital? 

Fovcity,  crime,  our  fajtlng  sclvooh? 

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Oever  solutions. 
Wayn^  Green '£  unique  neasonini;  1^  ininguing  —  tven 
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^n  he  presents:  It  is  lime  lo  bring  bgk  —  no(  crnmions 
^  to  bciLr  on  Americans  dilemmas.  Hl^  ttpin  on  America 
in  ihe  90*s  helps  us  to  understand  how  simple  ihe  seem- 
ingly complex  issues  ure.  All  it  takes  h  looking  at  ihem 
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76  73  Amateur  Radio  Todays  July,  1994 


"Some  cord  fusion  experiments 
have  reportedly  produced  power  den- 
sities higher  than  those  of  uraniuf?t-lu- 
eled  lissfon  reactors  » ,  .  Experiments 
thai  use  cracK-free  palladium  and  fol- 
low the  proper  procedures  now  rou- 
tinely produce  heat,  nuclear  products, 
or  both  .  .  ,  For  cold  fusion  to  occur, 
the  palladium  probably  must  transform 
No  a  ^}ecial  condition  of  matter,  akin 
lo  sijperconductrvity  .  .  .  None  of  ihe 
proposed  explanaiions  for  cold  fusion 
accounts  for  the  full  range  of  experi- 
mental observations," 

My  predictions  of  cold-fusion -pow- 
ered cars  with  a  sealed  unit  that  would 
provide  power  for  years  was  being 
backed  up  by  Nobel-Laureate  scien- 
tists. Sure,  the  first  products  will  be  big 
and  expensive.  You  only  have  to  visit 
any  science  museum  to  see  what  ear- 
ly steam  engines  and  internal  comt>us- 
tion  engines  looked  like,  Bui  as  we 
find  out  more  about  this  power  source 
I  believe  we'lt  have  fuel-less  planes 
and  $100  round  trips  to  Africa.  We'll 
probably  have  micro- sized  generators 
powering  wrisi  communicators. 
Shades  of  Dick  Tracy!  Our  homes  will 
be  heated  and  powered  by  units 
smailer  than  a  bread  box.  No  more 
need  for  oil.  gasoltne,  nalural  gas, 
coal,  those  big  wind  turlDines,  or  even 
inefttcient  solar  power. 

Free  power?  Just  about.  No  more 
gas  slations  or  oil  splits.  No  more  coal 
mining  or  well  drilling.  Welt,  we  need- 
ed something.  With  the  known  re- 
serves of  fossil  fuels  already  50% 


used  up.  the  era  of  low-cost  oil  and 
coal  was  coming  to  an  end. 

The  Opportunity 

With  the  deathblow  to  the  naysay- 
ers  by  the  Technology  Review  article, 
well  start  seeing  some  money  going 
into  R&D  here  in  the  US.  Japan  is  way 
ahead  of  us  in  this  field,  so  we've  3  lot 
of  catch-up  to  do.  GonsideriDg  the 
head  start  Toyota  has.  Tm  predicting 
that  perhaps  as  soon  as  the  1999 
model  year  we  may  see  a  free-energy 
Toyota  announced. 

We're  going  to  see  many  more  mil- 
lionaires and  billionaires  as  a  result  of 
this  new  industry.  And  we're  going  to 
see  a  mighty  scramble  by  the  power 
and  oil  companies  to  cope  with  Iha 
changes.  The  power  companies 
haven't  been  as  impressed  by  the 
naysayers  as  the  government,  so 
they've  been  helping  to  fund  some  re- 
search, I  suspect  they've  a  game  plan 
of  reducing  the  cost  of  electricity  with 
this  new  technologyp  and  thus  hoping 
to  stave  off  a  massive  move  toward 
home  power  units. 

One  outfit,  EN  ECO.  has  been  work- 
ing quietly  lo  get  as  much  control  of 
the  patent  applications  in  the  field  as 
possible.  This  cou*d  pay  off  big  for 
them.  Hie  scientists  involved  need  a 
business  organization  to  represent 
their  interests,  and  to  help  fund  therr 
continuing  research,  so  it's  a  good 
marriage. 

With  the  publication  of  "Coia  Fu- 
sion,'the  TV  documentaries,  and  the 


MU  arlide,  I  think  welt  even  see  the 
media  beginning  to  lake  a  positive 
look  at  what's  been  going  on. 

Yes.  the  chemistry  and  physics  In* 
vofved  with  cold  fusion  seem 
formidable.  But  when  you  remember 
that  even  the  experts  are  unable  to 
explain  what's  happening,  maybe 
coming  up  to  speed  In  this  new  lech- 
nology  isn't  as  impossible  as  self -de- 
feated people  alibi.  When  solid-state 
electronics  cam©  afor>g  in  the  1950s 
many  of  the  old  tube  people  gave  up 
and  didnl  even  try  to  keep  up.  Tran- 
sistors turned  into  ICs.  which  got  ever 
more  complex.  In  an  effort  to  build  a 
universal  controller  chip,  Intel  came 
out  with  the  4004.  This  was  upgraded 
to  the  S008.  the  first  8-bit  chip.  Hobby- 
ists took  one  look  and  decided  they 
could  lurn  this  oonlroHer  chtp  into  the 
heart  of  a  microcomputer  by  adding 
appropriate  software.  That  was  the 
beginnings  of  the  microcompuler  revo- 
lution, intet  upgraded  to  the  S060  chip, 
which  Ed  Roberts,  a  computer  hobby- 
ist, used  as  the  heart  of  his  Altair 
8800.  This  product  came  just  in  lime 
to  save  f^lTS-  They  had  bet  the  farm 
on  sol^d- slate  calculators,  which  they 
were  selling  for  S 130.  Just  as  cak:ula- 
tof  prices  dropped  by  about  90%  Ed 
announced  the  Altair  and  got  over  $5 
million  In  orders  rn  197&. 

So  t  had  lo  start  over  and  leam 
how  computers  worked.  It  wasn't  easy 
at  that  time  because  there  weren't  any 
textbooks  worth  a  damn. 

Now  Tm  teaming  about  palladium 


loaded  with  hydrogen.  Again  there 
are  no  textbooks  to  help.  I'm  learning 
about  nickel  and  hydrogen.  aixJ  so  on. 
And  Tm  not  doing  one  single  thing 
that  you  couldn't  do.  if  you  had  the 
interest.  I'm  leamirg  about  deuterium, 
tritium,  neutrons,  gamma  rays,  and 
so  on.  It's  exciting.  I'm  almost  begin- 
ning to  understand  the  arcane  lan- 
guage of  the  scientists  working  willl 
this  sluff . 

And  like  almost  everything  else  IVe 
tackJed,  I've  found  that  ft  ^sn't  a  ques- 
tion of  brains,  ifs  just  one  of  persever- 
ance. Edison  pointed  out  that  genius 
ES  99%  perspiration  and  I  have  no  rea- 
son to  question  him  on  it. 

Oh,  Ft  does  help  to  keep  an  open 
mind  and  absolutely  refuse  to  ignore 
anomalies.  Pretty  soon  you  find  that 
things  Start  fitttng  together  and  making 
sense. 

No,  no  one  yet  fvas  a  good  theory 
for  how  the  cold  fusion  effect  works, 
Bui  then  we  don't  have  a  theory  we 
agree  on  yet  for  electricity,  gravity  and 
even  Inertia.  Many  scientists  are  going 
back  lo  the  concept  of  *'ether*  as  a 
medium  in  which  radio  and  tight 
*waves"  travel,  if  you  read  much,  you'll 
be  reading  about  all  that 

As  you  get  into  all  this  yoult  find 
there  are  a  mass  of  newsletters  and 
departments  on  CompuServe  and  the 
Inlefnel  dedicated  to  discussing  these 
ideas.  What  there  isn't  is  any  guide  to 
ail  this.  And  don't  ask  me  to  volunteer 
for  that  one  .  .  .  I've  got  my  hands  fulj 
witli  cold  fusion. 


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Special  events 


Ham  Doings  Around  the  World 


JULY  4 

HARRISBURGt  PA  A  Hamfest  will  be 
held  toy  the  Harrisburg  RAC,  8  AM-2  PM 
(Set-up  at  6  AM).  Location:  Bressler  Picnic 
Grounds.  Contact  Steve  Gobat  KA3PDQ, 
f&OC  an  Tmii  Hd,  Eners  PA  17319;  (7t7) 

JULYS-IO 

GANDER,  NF.  CANADA  The  ARC  of 
Central  Newfoundland  (ARCON)  will  host 
a  Hamfest  at  Hoi  el  Gander.  Flea  Market, 
Seminars,  Banquet.  Contact  ARCON.  P.O, 
Box 281.  Gander.  NF,  Canada  AlV  m§. 

JULYS 

SOUTH  MILWAUKEE.  Wl  Tfw  South  Mil- 
waukee ARC  Inc.  will  l^ol^  its  25tli  annua! 
"SWAPFESr  at  the  American  Legion  Posl 
#434  grounds,  at  9327  S.  Shepard  Ave., 
Oak  Creek  Wl  Irom  7  AM-2  PM  GDI  TaJk- 
in  on  146,52  WA9TXB9  or  phof^  (4t4} 
762-3235. 

JULY  ^10 

INDIANAPOLIS,  In  The  mdianapolis 
Ham^esl  Assn.  will  host  the  ARRL  Central 
Div,  Convention  at  the  Marlon  County  Fair 
Grounds.  Flea  Market.  Exhibits.  Foaims. 
Banquet.  T-Hunts.  Contact  tndmnapolis 
HamfBSt  Assfi.,  RO.  Box  U776,  tndi- 
mmpolfS  IN  4^01.  Tei.  {3t  7)  251-4407. 


JULY  10 

BALTIhlORE,  MD  The  Maryland  Ham- 

fest/Comp titer  Fesi  will  be  held  at  Tlmoni- 
urn  Fairgrounds  on  York  Rd.  Set-up  2  PM 
Sat,  July  9th.  Tailgating  area  opens  at  6 
AM  Sun..  July  tOlh:  buiCdmgs  open  at  8 
AM.  VE  Exams  will  be  given  at  1 0  AM  only. 
PTB-regisl ration  is  required.  Call  Les  Mc- 
Ctum  W3GXT,  (410)  833-S667\c  pre-iBg- 
isler.  Tatk'in  will  tm  m  147.03  and  224.96 
MHz  Rptrs.  For  Hamtest  info,  call  (410} 
467-4634:  or  write  BRATS  Hamfest,  P.O. 
Box  5915,  BaHimore  MD  21208. 
PITTSBURGH,  PA  The  9th  a/inual  Ham- 
fest  o(  the  North  hlilis  ARC  wiU  be  held  3 
AM^3  PM  at  NoflhlarKi  Public  Library.  300 
Cumb^riaml  Rd.  Rea  Market,  Seminars. 
Silent  Key  Estate  Sale.  Tatk*in  on 
147.69/.09.  Contact  Don  Jackson  N3LAZ, 
915  Dale  Ave.,  Bramofd  Woods  PA  15015. 
TeL  (412)  935^3343. 

JULY  16 

lAI^CASTER,  PA  A  Computer  aixf  Em- 
Ironies  Show,  sponsored  by  Red  Rose  Re- 
pealer A^sn.,  will  be  held  9  AM-3  PM  at 
McCaskey  H.S.  Set-up  at  7  AM.  Talk-in  on 
1 47.015+.  Vendors  conlad  LBfry  Harman, 
Box  1S2,  Leola  PA  17540.  TeL  (717}  656- 
0129.  Fax  (717}  €5&3474, 

JULY  17 

VAN  WERT,  OH   The  Van  Wert  County 


Listings  am  tee  of  charge  as  space  permits  P^^se  send  us  your  Speciat  Event 
two  months  in  advaryce  of  the  issue  you  vifanf  it  to  appear  in.  For  examplB.  if  yau 
want  it  to  appear  in  the  January  issue,  we  shouid  receive  it  by  October  3t  Provide 
a  clear,  concise  summary  of  the  essentiat  details  about  your  Special  Event  Checii 
Special  Events  Fife  Area  mi  on  our  BBS  (603^924-93431  for  fistings  that  were 
too  late  to  get  into  publication. 


Fairgrounds  Commeiclal  8ldg.  will  be  tie 
location  lor  a  Hamfesl  sponsored  by  Van 
Wart  ARC  (WSFY).  Time:  8  AM-4  PM. 
Talk-in  on  146.850.  VE  Exams,  pre-regis- 
ttr  by  July  101  h:  Contad  Bob  HIgt}  KABfAF. 
12B38  Tomiinson  Rd.,  Rocktord  OH 
45862:  Tei.  (419)  79&57B3  (befon^  5  P/ML 
T-Hynt.  Hamfest.  For  info,  call:  Bob 
WD8LFY,  (419)  238-1877,  aim  5  PM. 

JULY  24 

QUEENS,  NY  The  Hall  Of  Science  ARC 
Hamfest  win  be  held  at  the  New  York  Hall 
of  Science  parking  lot.  Flushing  Meadow 
Paik,  47^)1  111th  Si  Doors  open  9  AM. 
Set4ip  al  7:30  AM.  Contact  (at  night  oniy), 
CtiBftas  Becker  WA2JM  (516)  $94-3955: 
or  Amie  Smffman  WB2yXB,  (718}  343- 
0J72.  Tatk-in  m  444 .200  WB2Z20/R,  or 
146.52  simplex. 

STICKNEY,  IL  Hamfesl  '94,  sponsored  by 
the  Dupage  ARC,  wiil  be  held  at 
Hawtt>orrve  Race  Course.  3500  South  Ci- 
cero  Ave  Flea  MarlteL  VE  Exams  and  CW 
leslfng  9  AM- 12  noon,.  waJk-ins  welcoaie. 
Please  have  your  orlgGrtaJ  Itoense.  a  pholo 
copy  anif  a  photo  ID.  For  labfe  into,  call 
(708}  985-9256.  For  advance  tickets^  send 
SASE  and  a  cheok  payable  to  DARC  to 
Hamtest  '94,  75 It  Walnut  Ave., 
WoodTi(^  tL  60517. 

JULY  30 

ASHEVtLLE.  NC  TTie  19lh  amwa?  West- 


em  Carolina  Hamfest  (ARRL  sarnSioned) 
wm  be  he«d  e  AM-4  PM  al  Haywood  Coun- 
ty Fair  Grounds  (near  Wayne svi lie  and 
Lake  Junaluska).  For  Dealer  and  Flea 
Market  info,  contact  Miriam  Smith  KB4C, 
(704)  683-4251.  Get  general  info  from  Oic*r 
Cfitcheit  KY2Y,  (704)  299-7356.  Ttckel 
contact  is  Ftay  Cra^jftiu  WBIHGO,  (704) 
298-7289:  Of  mail  an  SASE  to  WCARS, 
PO.  Box  1468.  Asheviile  NC  2880Z 

JULY  31 

SUGAR  GROVE,  IL  TT>e  Fox  River  Radio 
League  will  hold  its  annual  Hamfest  at 
Waubonsae  Comiruiwty  CoHege,  Route  47 
at  Harler  Rd.  Opeci  to  ihe  pubric  al  8  AM. 
Set'Up  Sal.  July  30lh  at  7  PM,  and  Sun. 
July  31st.  6  AM-8  AM.  VE  Exams  at  10 
AM,  Talk-in  on  145.470  (-600).  Contad  Bil! 
Schaben  WA9AUW,  (708)  2O3-4370:  or 
Mark  Hougaard  KB9FCC,  (708)  979- 1 71 7. 

AUG1 

DOYI^STOWN,  PA  Tbe  Wyndmoor  AR 
Repealer  Club  of  Doylestown  will  meet  at 
tfw  Doylestown  Towrtship  Skig,  Communi- 
ty Room  on  Wells  Road,  at  7:30  PM.  Inter- 
ested persons  may  call  Bob  Agans,  (215) 
348-7366.  The  Club  features  speakers  and 
videotapes  on  topics  concerning  amateur 
racfio.  and  tt>e¥  get  togethef  to  study  for  li- 
cense tests,  etc.  They  often  schedule 
weekend  exajrsions  to  ham  radio  events 


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The  POWER  STATION  is  a  12V  x  6.5  AmpHr  gel^eli 
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which  always  charge  the  battery  a  full  cycle,  this  damages  their  battery 
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THE  HAM  CONTACT 


P.O.  Box  3624,  Dept.  73 
Long  Beach,  CA  90803. 


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7S   73  Amateur  Radio  Today  •  July,  1 994 


AUG  S*7 

VERNON.  SO,  CANADA  The  3rd  annual 
Sky  High  Hamfesl  wtH  be  hdd  by  the  Nofth 
Oka/iagan  RAC.  at  Silvef  Siar  Mt.  Resort. 
Bea  MarkeL  Dimer  &  Dance.  HF  Station. 
More.  Contact  North  Okansgan  ARC,  P.O. 
Box  1706,  Vernon  BC  V1J  BC3,  Canada. 
For  hotel  reservations,  calf  h&0Q*663- 
4431 

AUG  6 

tNDtANAPOLIS,  IH  The  annual  WA9SNT 
Kamfesi  will  be  befd  at  ITT  Tecti,  insl. 
9511  Angola  Q.,  from  8  AM-3  PM.  Sel-up 
at  6  AM.  This  event  is  sponsored  by  the 
ITT  Radro  Club.  Talk-in  wi  145.25-.  Con- 
tact Dave  Jotmsion  K9HDQ,  (317}  875- 

VALPAHAISO.  IN  The  Poder  County 
Hainfsst  and  CompLrter  Show,  sponsored 
by  the  Porter  County  ARC  in  co-operation 
with  The  Porter  County  Tourism  Bureau, 
will  be  held  at  Porter  County  Expo  Center. 
Doors  open  at  B  AM  (set-up  at  6  AM).  VE 
Exams  9  AM- 12  Noon  Talk-in  on 
146.775/-6kc  131.8  PL  and  146  520  Sim- 
plex, Contact  Rich  N9Q10,  (219)  7&2- 
8701:  or  s^kJ  SASE  to  PCARC  HamFest, 
PC  Box  t78Z  Vai^mmso  fN  46384'1782, 

AUG  6-7 

JACKSONVIU-E,  FL  The  Greater  Jack- 
sonville Amateur  Rarfio/Compulef 
Show/ARRL  Northern  Rori<ia  Section  Con- 
vention, will  be  held  at  Osbom  Convention 
Center  in  downtown  Jacksonville.  Flea 
MarVei.  Hours:  9  AM-S  PM  Sal:  9  AM-3 
PM  Sun.  Set-up  at  2  PM-6  PM  Fri.  and  7 
AM-9  AM  Sat  VE  EKams  Sun.  at  9  AM. 
Contact  Greater  JacksonvUle  Ham f est 
Assn.^  P.O.  Box  27033,  Jacksonvitte  PL 
I  Tel.  (904)  350-9m. 


AUG? 

CROOKED  LAKE.  ANGOLA  IN  The  An^ 

nuai  Land  ot  Lakes  Angola  Hamfest.  spon- 
sored by  the  Lana  ot  Lakes  ARC.  wi  be 
held  6  AM-2  PM  at  Steuben  County  4-H 
Fairgrounds,  comer  o*  200 W  &  200  H.  VE 
Exams  tor  all  dasses.  Talk-in  on  147.180^ 
145.090  packet,  444.350  131.8  tone, 
444. 900/.  100,  224,94,  53.050,  Contact 
Sharon  Brown  WD9DSP,  905  WPkwy.  Dr., 
Pleasant  Lake  iN  45779.  m  (219)  475* 
5&97. 

MARSHFiELD,  Wl  Ihe  Marshfield  Area 
ARS  will  hold  Iheir  3fd  annual  Rcnic,  in 
WiWwood  Park,  beginning  around  11  AM- 
This  is  a  PotluckySwaptest,  Talk^in  on 
147,180,  Contact  Guy  A.  Boucher 
KB9GPJ,  W7  West  Thtrd  St..  Marshfi&fd 
Wi  54449.  T0L  (715}  384-4323-  PACK* 
En:KB$GPJ  ^  W$tHW.Wl.USANA. 

NORTH  TARBYTOWN,  NY  The  WestCh^ 
ester  Emergency  Comm.  Assn.  (WECA) 
will  hold  their  "WECA  Summerfest  1994*^  at 
Westchester  County  Center,  Junction  ot 
Rte  119  and  Bronjt  River  Pkwy.  Talk  in  on 
l47.06/,66.  Vendors.  Forums,  VE  Exams, 
and  more.  Contact  Jeanne  Ratfae^,  ($U} 
962*9666. 

PEOTONE,  IL  The  60th  annual  Ham- 
test/Computer  Festival,  sponsoreii  by 
Hamtesters  Radio  Club,  tnc.,  wilt  be  held 
at  Will  County  Fairgrounds  6  AM-3  PM. 
Rea  Market.  Set-up  Sal.  Aug.  6lh  at  6  PM- 
12  midnight.  Talk-in  on  146.52  simplex, 
146.64  (-)  (courtesy  of  STARS);  146,94  (-) 
{courtesy  ot  KARS).  For  info,  call  (708) 
535-AHAM.  Get  advance  tickets  (SASE 
and  check  by  July  20lh)  from  Dsvid  F, 
Braset  NF9N,  €933  W.  HO  SL,  Worth  IL 
60482,  let.  (708)  448*0560. 


SPECIAL  EVENT  STATIONS 

JULY  3 

RUSSIAVILLE,  tN  The  KokOmo  ARC  wi 
sponsor  a  Special  Events  Station  honoring, 
the  SesquEcentenniat  celebration  of 
Howard  County.  Operation  will  be  on  BO, 
40.  and  20  meters  in  the  bottom  25  kHz  of 
the  General  class  bands,  and  in  the  15 
and  10  meter  Novice  ctass  bands.  The  sta- 
tion wiJI  be  on  the  air  at  1400  UTC  and  will 
continue  tor  12  hours.  Please  QSL 
w/SASE  to  Dick  Elliot  N9iPA,  PO.  Box 
128.  Ri^siaviSe  tN4$9m 

JULY  4 

COEBURN,  VA  The  Lonesome  Pine  ARS 
will  operate  0^OZ-22O0Z  to  commemo- 
rate Coebum's  lOCfh  Centenfual  Celebra- 
tion. Operation  win  be  SSB  in  the  General 
phone  portions  of  10,  20,  and  40  meters. 
For  a  certificate,  please  send  a  9*  x  12' 
SASE  to  the  lonesome  Pine  ARS,  RO^ 
Box  2955.  Wise  VA  24293, 

JULY  4-5 

PLEASANTON,  CA  Uvemiore  ARK  wllJ 
(^rate  N5F0O  1700Z  Jiiy  4ih-0i00Z  Ju- 
ly 5tfi*  to  commemorate  the  Centennial  An- 
niversary ol  the  City  of  Pleasanton  The 
station  will  operate  from  the  Alameda 
County  Fairgrounds.  Frequencies:  CW 
7,125;  p*ione  14.250  and  28  485.  For  a 
QSL.  send  your  QSL  and  SASE  to  OfOl 
Ross  WABPYH/AG,  7005  Corinth  CL, 
Dublin  CA  94568, 

WILLIAMSBURG,  VA  The  Williamsburg 
Area  ARC  will  operate  W4TMN  1200Z  July 
4t?i-01002  July  5th,  to  celebrate  the  218th 
Anniversary  of  the  signing  ol  ttie  Dedara- 
lion  of  Independance.  F^'equencies; 
146.58.  28.350.  24.950.  21350.  18.150, 


14  270.  7.270  and  3.870.  For  an  unfolded 
certificate,  send  OSL  and  a  9"  x  12^  SASE 
to  Hershel  KfBi$  KE4GWV.  U5  Sand  m 
fid.  mimm^Hsrg  VA23i88. 

JULY  4-10 

AUSTIN.  TX  Amaiteurs  affiliated  with  the 
American  Sunbathing  Assn.,  the  Naturtst 
Soc.,  and  the  Federation  of  Canadian  Na* 
turists.  will  observe  the  19th  annual  North 
American  Nude  Awareness  Celebration  by 
operating  a  Special  Event  Station  near 
14265.  21.365.  and  28.465  W-  QBM.  For 
a  certiticate,  please  send  QSL  and  a  §*  x 
12"  SASE  to  Bob  Redootey  KF5KE  RO. 
Box  2008 1Z  Austin  TX  78720. 

JULY? 

BUTLEDGE,  GA  Attanfa  Chapter  49. 
QCWA,  wiil  demonstrate  arnateur  radio  on 
HF/VHF  starting  at  2  PM-9  PM,  EDSt  in 
supporj  of  Ihe  National  Kidney  Foundation 
of  Georgia's  annual  "Camp  Indepen- 
dence/' for  young  transplant  ellgibles  at 
Camp  Twin  Lakes.  It  allows  young  people 
to  see  and  participate  in  amateur  radio 
commumcations.  Frequencies:  7250, 
14250.  and  21,250  +/•  QRM.  using 
W4NZJ.  Alt  contacts  welcomed  and  invito 
ed.  For  a  special  oSL  card,  please  send 
your  contact  info  and  QSL  card  w/SASE  to 
Judson  F  Whathy  W4NZJ.  2t56  Wrndsor 
Dr.,  Snetivitle  GA  3027&, 

JULY  7-9 

PITTSBURGH.  PA  Station  WA3BAK  wilt 
be  on  the  air  Thurs.,  Fri.,  and  Sat.,  July 
7th-9lh,  09:00  to  23:00  hours,  En  conjunc- 
tion with  the  56th  annual  Soc.  tor  Preser- 
vation  and  Encouragement  of  Barter  Shop 
Quartet  Singing  in  America  (SPEBSQSA) 
Intem'l  Convention.  Frequencies:  20  me- 


»*•  Al 


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73  Amateur  Radio  Today  •  July,  1 994  79 


ters  ■  14  235/245  MHz;  15  meters  ■ 
21,300/320  MHz.  10  meters  -  28.300/320 
MHz;  2  ffietef^  -  146.610  -BOO  kHz;  220 
MHz  band.  224.00  -1.60:  440  MHz  baiKS, 
440.000  -5  MHz.  PackeL  W3HID 
e  W3IXR,#SWPA.PA.IJSA.NA.  Bob 
Schiesinger  is  Afwhor  Operator  All  OSOs 
wii!  be  coflltrmed  by  a  spedat  commemo- 
rative QSL  card*  courtesy  oi  Yaesu.  USA 
DSl  carets  ar@  available  to  WA3V3AK 
SWL's  who  $end  a  SASE  to  Bamer  Snop 
Binger$,  4952  Esther  Dr.,  San  Jose  CA 
$5124  USA 

JULY  9 

EAST  GREENWICH,  Rl  Ihe  Bd^  ARC 
will  operate  Kl  NOG  from  13002  to  18002, 
to  coindde  witti  the  annual  Yankee  Tune 
Up  at  the  New  England  Wireless  and 
Steam  Museum.  Operation  will  be; 
Phone — lower  portion  ot  the  20  meter 
General  subtand:  CW^Novice  portion  ot 
the  40  meter  band.  For  a  certificate,  send 
QSL  and  SASE  to  Bob  Hm  NE1E,  RO. 
Box  t68,  3  LOWSt  CU  Fiskevilte  Rt  02823. 
EASTON,  PA  The  Delaware-Lehigh  ARC 
will  operate  W30K  12002-24002  from 
the  Canal  FestlvaL  Operation  will  be 
on  3  96S.  7,265,  14.265.  21.366,  and 
2B.36S  MHz.  For  a  special  QSL,  send 
QSL,  Conlaet  number,  and  SASE  to 
DOM?  RD  4.  Greysione  Bidg..  Nazareth 
PA  18064, 

JULY  9-10 

raomi,  NY  station  KY27  wiU  be  opemt- 
ed  12O0Z'210O2  each  day  from  the  Sp*rtl 
of  Central  New  York  Hot  Air  Bafloon  Festi- 
val  and  Air  Show  at  the  Oswego  County 
Airport.  Sponsor  The  Oswego  AR  Emer- 
ger^cy  Service.   Operation  will  tie  in  the 


middle  of  the  General  80.  40,  20,  15  and 
10  meter  phone  bands;  the  Novice  portion 
of  10  meters,  and  t47.75/,15  MHz  For  a 
ceitiflcate.  s^nd  your  QSL  card  and  a  large 
SASE  to  Fred  SwrntOr^^i  KY2F.  RO,  Box 
5^7,  Oswego  NY  t3l2B. 
St  LOUIS,  MO  The  Monsanto  ARA  wM 
Operate  WBOBBN  from  1300  UTC'0300 
lire  (both  days),  to  commemorate  the  St. 
Loyts  Gateway  to  the  Gold  1994  Olympjc 
Fesltval  dosing.  Operation  will  be  in  the 
GenerBi  portion  ol  40,  20.  and  i5  meters, 
the  Movice  portion  of  10  meters.  147  36+. 
224.98%  and  443.55+.  For  a  special  OSL, 
ptease  send  a  9'  at  12'  SASE  tor  an  ufi- 
folded  OSL»  or  a  legal  siz^  SASE  for  a 
folded  QSL.  to  M.A.R4.,  PQ  Bqx  1596. 
Maryland  Heights  MO  63043. 

JULY  21-30 
EDMONTON,  ALBERTA,  CANADA   The 

Radio  Amateur  Educational  Society  will 
operate  VE6KDA  during  the  annuai 
Klondike  Days  Exposition.  Frequencies: 
1.870  when  conditions  permit,  3.750  0200 
UTC*0500  UTC;  7.2000  2300  UTC-0200 
UTC;  U.165,  21,220.  28.300,  and  14.050 
(CW)  when  conditions  permit.  For  a  QSL, 
send  QSL  and  SASE  to  RAES.  Ritchie 
Postal  Oomt  Box  75038,  Edmonton  AB 
T6E6K1,  Canada. 

JULY  2^-24 

PEHANG,  MALAYSIA  The  Malaysian  AR 
Transmitter  Soc.  will  sponsor  a  CW  Corv 
test  00012  Sat.  Jdy  23rd^23592  Sun.  Ju(y 
24th.  as  part  of  an  invitation  Jor  hams  to 
visrt  Malaysia  and  attend  the  "SEANET  94" 
Convention  in  hJovember  Operation  wiH  be 
on  160,  BO.  40.  20, 15,  arxl  10  meters  (no 
WARC  bands).  The  Contest  call  is  'CO 


SEA."  Contact  Seanet  Contesi  Manager 
1994,  Eshes  Razak  9M2FK,  PC  Box  13. 
10700  Penang,  Maiaysia. 
STRATFORD,  NY  The  Fuflon  County 
Mahlon  Loom  is  Committee  will  operate 
W2ZZJ  fmm  13002-20002  on  the  Ger^raf 
class  phone  portion  of  40.  20^  and  15 
melefs.  arxf  on  the  Novice  10  meter  phone 
band,  to  celebrate  the  163th  Anniversary 
of  the  birth  of  Or,  Mahlon  Loomis, 
the  American  wireless  telegraphy  pioneer. 
For  iterature  m(^  a  certificate,  send  OSL 
contact  number,  and  a  #10  SASE  10 
W2ZZJ,  5738  SmWY  29A,  Stratford  NY 
t3470. 

JULY  25-31 

CANTON,  OH  The  Canton  ARC  will  oper- 
ate W6AL  to  celebrate  the  Pro  Football 
Hall  of  Fame  Greatest  Weekend.  Time: 
14O0  UTC'020€  UTC  Frequencies:  SSB  - 
28.350,  24,950,  21.350,  18.150.  14.270, 
7,270h  and  3.670  MHz;  CW  ^  2$,125, 
24,910,  21.125,  18.080,  14.050,  10,120, 
7.125.  and  3.700  +/-  QRM.  There  will  also 
be  RTTY,  Pacl<et,  AMTOR,  Salellite.  2-me- 
ter and  6-meter  FM/SSB.  SWLs  are  wel- 
come. For  an  unfolded  certificate,  send 
your  QSL  witli  contact  number  and  a  9'  k 
12'  SASE,  with  two  units  of  first-class 
postage.  For  a  QSL  or  a  folded  certificate, 
send  your  QSL  with  conlad  #  and  a  #10 
{business  size)  SASE  to  Randy  Phelps 
KD8JN.  1226  Deiveme  Ave,  SW,  Canton 
QH447tO-1306. 

JULY  30-31 

DANBURY,  CT  The  Candl0«OOd  ARA 
ai^d  lis  members  will  sponsor  the  1994 
Connecticut  QSO  Party  from  20002  July 
30^-20002  July  31st.  with  a  rest  period 


D4002-12002  Get  details  from  Frank  Et- 
2lerN8WJ<Q,  (203)350-3523. 

AUG  5-7 

IIILWAUKEE,  Wl  Members  of  the  Mil- 
waultse  ABES  will  operate  Station  VV9WK 
to  ceiebfBie  ttw  4th  annual  'Picnic  Ham* 
held  at  Menomonee  ParK  in  Lannon  Wl. 
Operation  wiB  be  in  the  Gerwral  phone  and 
CW  bands  on  75,  40,  20.  15  aivJ  10  me- 
lers.  For  a  cerlificale,  send  OSL  and  a  9"  at 
12"  ifivQlopt  (wtth  2  tHitts  of  postage)  to 
WaWK  c/o  John  Leekty  757  N  Broadway, 
SiMte  306,  mwmikee  Wt  5320Z 

AUG  6-7 

BWNEGAT  UGHT,  NJ  The  Old  Barney 
ARC  wfti  opemie  W20B  from  "OLD  BAR- 
NEY," ihe  Barnegat  Lighthouse  (Long 
Beach  Island  IOTA  NA-111).  to  coin- 
memorate  National  Lightl^ouse  Day.  Time: 
3000  UTG-OOOO  UTC  each  day,  Frequen- 
des:  Look  in  Itie  lower  25  kHz  of  the  Gen- 
eral phone  bands;  40,  20,  15,  and  10  me- 
ters, plus  146-52  simplex,  146.835  Rptr, 
and  other  local  Rptrs.  For  a  special  QSL, 
send  a  9"  jc  12*  SASE  with  2  units  of 
postage f  via  NU2F.  For  more  info,  contact 
QSl  W20B  v/a  NU2f,  Joe  Retshlnger  Sr., 
75  Joshi;a  Or.,  ManAhawkm  NJ  QB050 
USA 

AUG  7-1 3 

POTTS VILLE,  PA  The  Schuylldl  ARAn* 
Operate  N3ILC  M^  Tlh-Aug  I3th,  to  j^le- 
brate  the  SchuyikJB  Coun^  Fair  Operation 
wii  be  both  CW  and  phone  on  the  General 
and  Novice  subbands.  For  a  certificate, 
send  QSL  and  SASE  !o  Bd  Brennan 
N31LC,  520  Spnng  Garden  St.,  PattsvIKe 
PA}790Ur651. 


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Random  output 

Continued  from  page  8$ 

got  a  big  laugh  around  the  office,  stno©  Tm  80 
conservative  I  make  Rush  Limbaugh  look  like  a 
'New  Dealer").  I  also  got  accused  ot  being  a  fas- 
cist One  angry  gent  who  didn't  have  the  courage 
to  give  his  return  address  wrote  to  Wayne  instead 
of  me  and  said  I  must  be  a  new  ham,  since  I  didn't 
know  the  first  thing  about  radio  or  regulations,  and 
that  I  should  not  be  allowed  to  write  any  more 
columns  (for  the  record.  I've  been  licensed  for  21 
years).  Go  figure. 

At  the  very  teast,  I  expect  the  san^e  respect 
fmm  you  as  1  give.  I  do  not  write  down  lo  you.  nor 
do  I  assume  that  you  are  all  ignorant.  I  do  no!  ^m 
how  long  youVe  been  a  ham,  rur  do  I  assign  any 
prestige  or  instant  authodiy  to  any  partJcular  class 
of  license.  If  you're  going  to  bother  to  write  to  me. 
please  have  a  rittJe  respect  for  yourself  am/  me. 
We  can  disagree.  l>ut  let's  fem ember  to  use  logic 
to  make  our  points,  not  insults 

All  I  did  was  suggest  that  we  give  some 
thought  to  why  we  fmd  it  necessary  to  carry 
around  radios  capable  ol  transmitting  on  poHce 
and  other  public  sendee  h'equencies.  1  wanted  you 
folks  to  mink  alxiut  it.  If  you  feel  threatened  by 
that,  then  I  suggest  you  probably  need  to  do  a  lot 
more  self-examination  on  this  Issue  than  the  rest 
of  us. 

As  always,  I  appreciate  every  single  letter  that 
comes  in.  I  don't  care  if  you  agree  with  my  opinion 
as  long  as  you  actually  have  one.  Having  an  opin- 
ion  means  more  than  just  a  knee-jerk  reaction  to 
something  that  offends  or  threatens  your  belief 
systems,  it  means  taking  all  of  the  available  input 
and  fomiing  your  own  ideas.  It's  not  difficult  arKl 
ygu  don't  have  to  be  a  college  graduate  to  do  it. 
but  it  does  take  effort.  Mental  effort. 


&0  73  Amateur  Radio  Today  •  Jufy.  1 994 


■^^  Number  26  on  ) 

Barter  w  buy 


your  Feedback  card 


Turn  ycyr  old  ham  ancf  computer  gear  rnto  cash  now.  Sure,  you  can  wait  for  a  hamfest 
to  try  and  dump  ji,  but  you  know  you'fl  get  a  far  mors  realistic  price  if  you  have  it  out  where 
100.000  active  ham  potential  buyers  can  see  it  than  the  few  hundred  local  hams  who  come 
by  a  flea  market  table.  Check  your  attic,  garage,  ceilar  and  closet  shelves  and  get  cash  for 
your  ham  and  computer  gear  before  it's  too  old  to  sell.  You  know  you're  not  going  to  use  it 
again,  so  why  leave  it  for  your  widow  to  throw  out?  That  stuff  isn't  getting  any  youngerl 

The  73  Flea  Market,  Barter  'n'  Buy,  costs  you  peanuts  (aimostj^comes  to  35  cents  a 
word  for  individual  (noncommercial)  ads  and  $^.00  a  wofd  for  commercial  ads.  Don't  plan 
on  telling  a  long  story.  Use  abbreviations,  cram  rt  in.  But  be  honest  There  are  plenty  of 
hams  who  love  to  fix  things,  so  if  it  doesn't  work,  say  so. 

Make  your  list,  count  the  words,  including  your  call.,  address  and  phone  number.  Include 
a  check  or  your  credit  card  number  and  expiration.  If  you're  placing  a  commercial  ad,  in- 
clude aa  additional  phone  number  separate  from  your  ad. 

This  is  a  monthly  magazine,  not  a  daily  newspaper,  so  figure  a  couple  months  before 
the  action  starts;  then  be  pre  pared  ►  If  you  get  too  many  cails,  you  priced  it  low,  If  you  don't 
get  many  caKs,  too  higii. 

So  get  busy.  BEow  the  dust  off,  check  everythcng  out,  make  sure  it  still  works  fight  and 
funebe  yoo  can  help  make  a  ham  sure  it  still  works  right  and  junefae  you  can  help  make  a 
ham  newcomer  or  retired  old  timer  happy  with  that  rig  you're  not  usirQ  now,  Or  you  might 
get  busy  on  your  computer  and  put  together  a  list  of  smaii  gear/parts  to  send  to  those  inter- 
ested? 

Send  your  ads  and  payment  to  the  Barter  'r'  Suy,  Judy  Walker,  70  Rt,  202 N,  Peterbor- 
ough  NH  0S45a  and  get  set  for  the  phone  calls. 


The  deadline  lor  the  August  classi- 
fied ad  section  is  June  9, 1394. 

ALL  ABOLFT  CRYSTAL  SETS.  Tiieo^ 
ry  and  constructton  of  crystal  set  ra- 
dios. $9,95  each,  ppd  USA.  Send  to: 
ALLABOUT  BOOKS.  Dept,  S.  P.O. 
Box  22366,  San  Diego  CA  921 92. 

BNB200 

CUSTOM  MADE-HAND  TOOLED 
leather  products  with  your  initials, 
name,  call  ietters.  Photo's  &  estimates 
available.  Key  rings,  wallets,  belts, 
purses,  hanging  signs,  specialty  items. 
GREAT  GIFT.  LEATHER  &  WEST,  67 
Causeway  Rd..  West  Swanzey  NH 
03469.  (603)352'6256-  9-4  pm.  M-F 
ET  BNB215 

SELL;  NOG  15m  QRP  transceiver, 
used  ittle,  A1  condition,  $200,00.  av. 
Couch,  2029  JoAnn,  Newton  KS 
67114.  BNB220 

QSL  SAMPLES-  50  cents.  SAM- 
CARDS,  48  Monte  Carlo  Dr.,  Pitts- 
burgh PA  15239.  BNB275 

ATTENTION  HAMS!  Subscribe  to  6- 
50  Worldwide  for  Six  Meter  Enthust- 
astSt  OX  Digest  for  DX  Chasers,  or 
The  Novice/Tech  Report.  Call 
(817)694^4047  or  FAX  (817)694-2522. 

Br^B292 

COMMODORE  64  REPAIR,  Fast  turn 
around.  SOUTHERN  TECHNOLGIES 
AMATEUR  RADIO,  10715  SW  190th 

Street  #9.  Miami  FL  33157,  (305)238- 
3327.  BHB29S 

KIT  BUJLDERS^Announcing  a  NEW. 
SYNTHESIZED  qrp  Transmitter/ 
Transceiver,  the  ARK4.  Get  on  the  afr 
for  only  $99.95f  {Transmitter  Kit  only) 
Buy  as  little  or  as  much  as  you  want 
Full  Transceiver  Kit  w/case  only 
$199.95.  One  board,  no  wiring,  top 
quality  components  &  PCB.  GUARAN- 
TEED TO  WORK.  For  Info  send 
SASE;  Call/Write  10  order:  S  &  S  EN- 
GINEERING, 14102  Brown  Road. 
Smithsburg  MD  217S3;  (301)416- 
0661 .  BNB304 


WANTED:  Electron  Tubes,  ICS,  Semi- 
conductors. ASTRAL,  P.O.  Box 
707ST,  Linden  NJ  07036.  Call 
{800)666-8467.  BNB307 

KENWOOD  AUTHORIZED  REPAIR, 

Also  ICOM,  Yaesu.  GROTON  ELEC^ 
TRONICS,  Box  379,  Qroton  MA 
01450.  (508)448-3322.  BNB310 

RCI-2950  OWNERS:  New  modifica- 
tion manual  including  Power  increase. 
Clarifier  modification.  Modulation  in- 
crease. Operating  hints,  and  more- 
Parts  included.  Only  S20.00  ppd  in 
U-S^  (Missouri  residents  add  $1.15 
tax).  SCOTT,  P.O.  Sox  510408,  St., 
Louis  MO  63151-0403.  (314)846- 
0252.  Money  Orders  or  COD. 

8NB340 

HR2510,  RCI2950,  CONNEX  3300, 
COBRA  148,  GALAXY  SATURN,  plus 

many  more  kits  to  increase  your  mod- 
ulation, $19.95.  (800)536-0109. 

B.NB350 

KIT  BUILDIRSI  Complete  itst  of  165+ 

kit  vendors.  #10  SASE  4-  $3.00  USD 
to;  RUTENBEB  ENGINEERING, 
38045  10th  St.  E.  #H75-AR,  Palmdaie 
CA  93550.  BNB365 

QSL  CARDS  —  Standard  and  cus- 
tom. Your  ideas  or  ours.  Excellent 
quality  Foil  stamping  avail alDle,  Many 
designs  and  type  styles.  Catalog  and 
samples  $1,00  refundable.  WILKINS, 
Dept.  A,  Box  787,  Atascadero  CA 
9342a  BNB370 

MANUALS  KW940  Owner  and  Shop 
manual  with  schematic,  $20.00;  also 
Heathkit  SB220-1  manual  and 
schematic,  $20.00;  also  NEW  3-500Z, 
$85.00.  (21 0)435-6190.  BIMB381 

NEW  NN1G  CW  SUPER-'HET  SIN- 
GLE BAND  TRANSCEIVER   KIT. 

Available  in  20M,  30M,  40M,  80M. 
$59.95  plus  $3.75  S/H.  (Catalog-2 
Stamps).  DAN'S  SMALL  PARTS  & 
KITS,  1935  South  3rd  West  #1,  IVIis- 
soulaMT59S0l.  BNB385 

Continued  on  page  83 


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versus  time  s£6rt-up  thorQcteristic-even  radios  of  the 
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the  abusers  Oft  your  repeateri  Or  help  you  keep  tracfi 
oF  the  number  or  radios  per  Qccdunt  on  commerciol 
repeoterspO  decoding^  os uuell  ds 

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CIRCLE  248  PN  READER  SERVICE  CARD 


PERFORMANCE 
AND  VALUE 

WITHOUT  COMPROMISE 


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Voice  Mail  Systems 


CIRCLE  144  ON  READElt  SERVtCE  CARD 

73  Amateur  Radio  Today  •  July,  1 994  81 


New  products 


Number  27  on  your  Feedback  carrf 


Com  pi  fed  by  Charles  Warrington  WAIRZW 


HAMTRONICS 

Hamtronics  has  announced  the 
new  COR-6  module — a  voice  ID  re- 
peater CO rtrolEer  combining  COR  cir- 
cuits and  a  real-voice  ID  on  one 
board.  I!  can  be  used  with  transmitter 
and  receiver  modules  Ip  iTiake  ^  sim- 
ple, low-cost  repeater 

A  digital  IC  records  up  to  20  sec- 
onds of  your  voice,  using  audio  from 
the  repeater  receiver  The  un(t  in- 
clucies  tail  and  lime-oul  timers,  cour- 
tesy beep,  and  a  soiid-stale  relay  to 
key  the  transmitter, 

The  kit  price  is  $99;  or  the  unit  is 
available  wired  and  tested  for  $149.  A 
catalog  is  aiso  availabie.  For  more  in- 


formation contact  Hamtronics,  Inc., 
65-F  Mout  Rd.,  Hiiton,  NY  U4S3- 
9535:  (716)  392^9430,  FAX  (718)  392* 
9420.  Or  circle  Reader  Ser./[ce  No. 
202. 


B+K  PRECISION 

B+K  has  introduced  their  first  digital 


mufti  meter  that  is  truiy  pocket-sized — 
the  instrument  is  only  4.4 "  x  2.2"  x  0.4' 
and  weighs  only  3.5  ounces  with  bat- 
teries. The  Model  2700  DMM  mea- 
sures AC  and  DC  volts  and  resistance, 
wtth  data  hold,  range  hold,  audtbfe 
continuity  lest,  diode  test,  bar  graph, 
and  3200  coy nt  LCD  display. 

Data  hold  freezes  the  display  to 
hold  a  reading.  Range  hold  allows  the 
user  to  defeat  autoranging  and  select 
one  specific  voltage  or  resistance 
range  for  ail  measurements.  This  is  the 
only  pocket  DMIVI  to  olTer  ail  these  fea- 
tures. 

For  more  information,  visit  your  fa- 
vorite dealer  or  cont^t  Bi-K  Precision, 
6470  W.  Courtfand  St,  Chicago,  ii 
60635;  (312)  889-1448,  FAX  (312) 
794-9740.  Or  Circle  Reader  Service 
No.  204. 


SINCLAIR  RADIO  LABS 


Sinclair  Radto  Labs  has  introduced 

Bn  intelligent  site  monitor  for  remote  RF 
transmitters  and  associated  antenna 
equipment  The  AMV-6A  measures  RF 
power  from  1  to  990  watts  in  both  the 
fonrt/ard  and  reflected  mode  simultane- 
ously, allowing  for  easy  VSWR  calcula- 
tions. 

Near  Intuitive  setup  and  program- 
itiing  make  this  power  monitor  simple  to 


use,  and  no  computer  or  other  ancillary 
equipment  is  required  for  irtstailation. 
The  unit  allows  system  power  and 
VSWR  tests  without  disconnecting  coax 
lines. 

For  more  informalion  contact  Sinctair 
Radio  Laboratories,  inc.,  675  Ensminger 
Rd,  Tonawanda,  NY  74150;  (716)  874- 
3682,  (BOO)  288-2763,  FAX  (716)  874- 
3682.  Or  circle  Reader  service  No.  206. 


PACIFIC  SCIENTIFIC 

The  same  commercial  duty  reliabiti- 
ly  found  In  Redi-Llne  mobile  electric 
generators  Is  now  available  in  an  elec- 
tronic inverter  to  meet  your  portable 
power  needs.  The  Hedi-Line  model 
DA1 21-24000  solid-state  inverter  op- 
erates from  12  VDC  vehicle  batteries 
to  run  120  VAC,  60  Hz  equipment 


wherever  commercial  power  is  not 
conveniently  available. 

The  new  Redl-Line  inverter  will  op- 
erate sensitive  electronic  equipment 
requiring  a  regulated  output,  including 
personal  computers,  and  Is  ideal  for 
equipment  requiring  up  to  2000  watts 
(continuous),  2400  watts  (for  up  to  15 
minutes),  and  surge  output  of  up  to 
5900  wafts,  for  loads  like  heavy-duty 
power  tools  with  high  starting  currents. 
Power  conversion  efficiency  is  be- 
tween 85-93%. 

A  brochure  with  specifications  and 
other  practical  Information  is  available 
for  $4  to  cover  shipping  and  handling. 
For  more  information  contact  Pacific 
Scientific,  inquiry  Handling  Depart- 
ment 1084  Oid  Colony  Road,  Laite 
Forest,  IL  60045;  (815)  226-3100,  FAX 
(815)  226-3080.  Or  circle  Reader  Ser- 
vice No.  201 . 


TIARE  PUBLICATIONS 

Work  the  world  with  1  watt!  Make 
contacts  of  over  a  thousand  miles  us- 
ing just  milliwatts!  Thafs  just  a  sample 
of  the  fascinating  fun  you  can  have 
with  the  new  book  Low  Power  Commu- 
nications -  Votume  2  -  Advanced  QRP 
Operating. 

Conceived,  coordinated,  and  edited 
by  Richard  H.  Arland  K7YHA.  the 
book's  eight  chapters  were  written  by 
some  well-known  QRPers,  including 
73*s  own  Mike  Bryce  WB8VGE.  Chap- 
ters cover;  QRP  DXing»  contesting, 
satellites,  antennas,  solar  power,  mi- 
cro- and  ml  Hi -watting,  and  DXpedition- 


ing  on  a  QRP 
budgeL 

The  book  is 
illustrated,  and 
is  priced  at 
$19.95.  (t  is 
available  from 
your  favorite 
dealer,  or  order 
direct  from  Tiare 
(add  $2  USA,  $3  elsewhere  for  S  &  H). 
For  more  information  contact  Tiare 
Pubiications.  P.O.  Box  493.  Lat<e 
Geneva,  Wi  53147;  (800)  420-0579, 
(414)  248-4845.  Or  circle  Reader  Ser- 
vice No.  203. 


KANGAROO  TABOR 
SOFTWARE 

Kangaroo  Tabor  Software  has  an- 
nounced the  new  CARMAN  2.0  com- 
puter-assisted prediction  manger.  This 
is  a  professional-quality  ION  CAP  pack- 
age that  allows  anyone  to  use  the  most 
advanced  propagation  routine  interfac- 
ing with  the  ELNEC  and  MINI  NEC  an- 
tenna analysis  gatn  patterns. 

CAPMAfsl  is  the  versatile  menu-driv- 
en skyway  analysis  package  devel- 
oped by  Kangaroo  Tabor  Software  and 
the  prime  author  of  lONCAP.  CAPMAM 
delivers  lONCAP  input  file  constnjction 
and  management^  two  integrated  exe- 
cute functions:  the  ability  to  view  and 
manipulate  huge  output  files,  and 


graph  teal  display  of  output  parameters 
for  multiple  target  locations  and  time 
periods. 

This  product  contains  a  full-featured 
location  database  and  can  be  easily 
customized.  The  CARMAN  package 
requires  a  386  or  better  PC  or  compati- 
ble. The  lONCAP  program  Is  included 
in  the  CARMAN  package^  which  is 
priced  at  $89  ppd.  in  the  USA  (else- 
where add  $3.50  S  ^  H).  For  more  in- 
formation contact  LUCAS  Radio/Kan- 
garooTabor  Software,  2900  Vaimont 
Hd.,  Suite  H,  Boutder,  CO  80301;  (303) 
494-4647,  FAX  (303)  494-0937.  Or  Cir- 
cle Reader  service  No.  205. 


Aclypse  Corporation  has  an- 
nounced the  ADR-1  Robot  Kit,  a  little 
something  different  for  the  ham  who 
has  everything.  The  robot  is  27"  tall  x 
14"  in  diameter  and  weighs  16 
pounds.  The  complete  kit  has  an  on- 
board computer  system  that  features 
voice  recognition  capabilities.  English 


ACLYPSE  CORPORATION 

speech  output,  power  motor  drive,  and 
a  battery  with  monitoring  and  recharge 
system. 

No  electronics  or  advanced  com- 
puter experience  Is  required.  Con- 
struction takes  two  to  six  hours  and 
requires  no  special  tools.  The  robot 
has  its  own  operating  system  and 


a  BASIC  programming  language  is 
built  in.  The  complete  kit  Is  priced  at 
$299. 

For  more  Information  contact 
Aciypse  Corporation,  RL  2.  Box213H, 
Worthington.  iN  47471;  (812)  875- 
2852,  BBS  (312)  875-2836.  Or  circle 
Reader  Service  No.  207. 


82  73  Amateur  Radio  Today*  July,  1 994 


^  *i  «   * 


Barter  'n'  buy 

Cofitinued  from  page  81 

SERVICE MOMTORS WANTED 

SERVICE MONITORS  . , .  - .  WANTED 

Any  tate  mode) Test  Equipment. 

CaJI.  {408)241-7376.  BNB390 

irS  BACK!  The  return  of  the  HW-8  Haudbookl 
Second  printing.  Modifications  for  the  Healfi  QRP 
rigs.  First  diass  maii  $11.  DX  add  $4  for  air  mail 
shipping.  Mike  Bryce,  WBBVGE,  2225  Mayflower 
IMW.  Massillon  OH  44647.  BNS404 

MAHLON  Looms,  INVENTOR  OF  RADIO; 
(patented  1872)  by  Thomas  Appleby.  (Copyrighl 
1967).  Available  from  JOHAN  K,V.  SVANHOLM, 
N3RFt  SVANHOLM  RESEARCH  LABORA- 
TORIES, RO.  Box  81,  Washingion  DC  20044. 
pjease  semi  $25.00  donation  with  S5.00  for  S&H. 

BNB420 

BROWNIES  QSL  CARDS  SINCE  1939.  Catalog  & 
samples  $1  (fefundable  with  order).  3035  Lehigh 
Street,  Allentown  PA  1 81 03.  BNB430 

QSL  CARDSIll  Customize  one  of  26  standard 
formats,  or  create  your  own  design.  FREE  info- 
packet  (75  cent  stamp  appreciated).  CHESTER 
QSL's,  Dept.  A,  2  South  Commercial,  Emporia  KS 
66801.  (316)342-^792,  FAX  (316)342-4705. 

BNB434 

BUTTERNUT  ANTENNAS.  NEW— in  box.  C2)HF6- 
VX,  $125.00:  (2)HF5B,  $200  00;  {2}HF2V.  $110.00: 
(1  )HF7VX.  St50.CX3.  (210)435-6190.  BNB435 

RADIO  DOCTOR  VJDEOS  for  Repair  f^nd  Align* 
meni  ol  HF  Trans ceivers.  Reviewed  by  Gordon 
West,  January — 73  Magazine.  Videos  for  popular 
KENWOOD.  YAESli.  and  tCOM.  ORDERS: 
(800)788^1416  MC/VISA.  Catalog:  SASE  (2 
stamps):  RADIO  DOCTOR,  710  Teague  Or,  Ken- 
nesaw  GA  30144.  BN3442 

FREE  ,  .  .  Ham  Radio  DX  Gospel  Tracts,  SASE: 
N1GDP,  RAR-QFC,  RO.  Box  8.  Harmony  ME 
04942.  BNB443 

RSPEATER  PROGRAMMING  SDPTWARE.-Use 
yCHlf  PC  and  modem  to  generate  DTMF  tones. 
Send  SASE  to  KM9S.  Box  771 .  Franklin  JN  46131 . 

BNB460 

GOOD  DX  LOCATION  on  the  second  highest  hill 
on  Ihe  East  Coast.  Four  bedroom  yellow  brick 
house,  overlooking  Sandy  Hook  Bay.  65'  military 
type  tower.  Call  (304)462-5575.  BNB505 

CRYSTALS;  High  quality  for  your  VHF/UHF 
and  SHF  iransverter  projects.  SASE.  WA3IAC, 
7148  Montague  St.  Philadelphia  PA  19135. 

BNB515 

CELLULAR  PHONE  PROGRAMMING  PACK- 
AGE! Program/Reprogram  cellular  phone  (s^ 
Change  ESN  and  NAM.  Change  or  Clone  ALL. 
$200.00  Complete.  Call  (419)351  ^7713.      BNB520 

CDROM-94  MAM  RADIO  CALLSIGN  DATA  BASE 
Ham  Radio  Callsign  Database  with  hundreds  of 
PC  Compatible  programs,  radio  mods,  TCP/IP 
Usenet.  Ham  Radio  Archives.  FCC  Rutes  &  Regu- 
lations.  cun^enl  exam  question  pools,  and  Canadi- 
an Call  Signs.  Only  524.95.  with  Windows/TX)S  In- 
terface, tncludes  shipping!  Send  check  (o: 
CDROM.  2348  Karen  Dr,,  #6.  Santa  Clara  CA 
95050  or  call  {408 J 241  -7376  with  your  Visa  or  MC, 

BNB540 


-  BUY  *  SELL  -  TRADE 

ALL  BRAN[)SOF 
2 -WAV  RADIOS  & 
ACCESSORIES 

CstJ  or  Write  for 
a  Cuaant 
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Billings,  MTS9 102 

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CIRCLE  2Q  ON  READER  SEI^VJCE  CARD 


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Wflai  v^ttiuJIlI  W(if   till  in  thj^  ci'n^io?  I  IncJ  ilv 
utup  L>a  3  £kii  ^tkS  Ilk'  Klidp  m  ttk:  iLindiiiL 
Willi  ^  ^-miai  tmi  Onh  iOk  T^"  in  Uk  ik:xi 

t^irfj   S**  1  fm  tint"  ufi  tkjTtri';;  thj  Stfix^Bii-nl 

nlvtt  jli  ilx*  rwiyhhi'r\  ucfij  bavy.  fcd  li  wiih  coax,  Ni»w  I  m  paling 

2\}m    S5*      -film   S79      75orSlhii   S99      IfiOm     St  3^ 

An  ten  nan  West  Or^^  i^uio^^J'™^ 

CIRCLE  363  ON  HEADER  SERVICE  CARD 


Small  Talk        w 

MICRO  1.2  8  2B  VOICE  RECORDEIt  IDENIfflEftS  !■ 


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HHaOPHORE,  SWITCHES  WO  FUli  OOCyHEHTATOI 


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tm 


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SHUSZE 


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8  Om  SP&UEI  CMTTFUT 

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TO OltDERiCALL  l-(800}-588-4300 IISIKS'"'' 


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CIRCLE  281  ON  REAPER  SERVICE  CARD 


Sell  Your  New  &  Used  Gear  In  BARTER  'N'  BUT 

Classified  Ads  Work[  Call  Judy  Walker  today.  1-800-274-7373 


1691  MHz  Weather 
Satellite  System 


1691  MHz  Pre-amp. 
model  TS-1691-P.  Amp 

1691  MHz  Receiver 
model  TS'1 691 'Recvr 

Decoder  Board  &  Software 
model  TS-VGA-SAT4 


$250 


$450 


S349 


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SI 


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ItfE  AfilH^  ES  QAP  TiCHMlMOl'V  •T>4t  AMS A  f  » IS  C4P  TfOlHOlOC Y 


Jill  Airtemi  wUi  No  Earih  Uss? 


1feS.«.  the  answer  Is  GAP'S 


llACKrABD 


}f  you're  looking  lor  an  anten- 
na that  can  o^jt  perKxin  the 
otlier^  m^  givt  you  the  edge, 
you  re  lookfnQ  \x»  i  GAP.  TTie 
Chdilenoer  OX-Vltl  ts  the 
TTvoliiicnafy  design  Ih^ 
9P5MF5  yotf  tfmtantk  ^ 
lasAMand  opafiiNMi  ind 
omoled  eftioency  wtmkMr 

thai  ifnivafts  Evth  Loss. 
fiAP  dEHws  trm  m  «bf]H 
4M  ^eur  pMer  dpesit 
dtsapfKar  mo  tsms  grounl  Put 
t  up.  Tum  It  on.  No  tymng.  Nfl 
frustration.  GAP  d«livsrs 
evQrylhing  bul  ti^  ha^e^. 
And  —  GAP  delivers  ai  a 
fractioa  of  Ihe  cost  Qt  tfie 
'so-called"  competliyon. 


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73  Amateur  Radio  Today  •  July,  1 994  83 


Where's  the  Fun? 

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73  Amateur  Radio  Today  July,  1994  87 


■^ 


Ham 


9  § 


Nuinber  2d  on  your  Feedback  card 

M  OUTPUT 


David  Cassidy  NIGPH 


Vm  Back! 

You  though  I  you'd  gotten  rid  of  me. 
dWn't  you?  You  ihought,  "Cassidy  has 
finally  slopped  beating  his  head 
against  the  wall  and  given  up."  didn't 
you?  Ha,  Ha  Ha ...  No  such  IlcW 

Actually,  an  overw helming  nu miser 
of  readers  called  or  wrote,  demanding 
that  J  break  the  setf-imposed  silence 
and  resume  writing  this  column  {OK. 
OK.  it  was  only  12  lettefs).  To  that 
brave  dozen  go  my  heartfelt  thanks.  It 
you're  wondering  why  i  took  a  few 
months  off.  It's  simple.  Orie.  1  was  try- 
irtg  to  put  together  the  Amaleur  Radio 
Child  Search  organiZ3ti<Ki  thai  I  wrote 
about  back  in  Febn^ary  (more  on  this 
later).  Second.  I  stmply  ran  out  of 
things  to  say.  Sure.  I  could  have  put 
together  a  coupie  of  puff  pieces  to  gel 
me  over  the  last  few  months>  but 
frankly  t  have  more  respect  for  you 
than  IhaL  Judging  froiti  my  mail,  most 
of  you  who  read  '"Random  Output"  at 
least  have  a  pulse.  Many  of  you  can 
actually  write  a  decent  letter  and  form 
a  logical  argument,  either  agreeing 
with  me  or  disagree irg  with  me  (more 
on  this  later,  too).  I  figured  you  would 
be  able  to  tell  thai  i  was  spinnnirvg  my 
wheels  so,  unlike  many  of  the  writers 
in  this  field  (no  names  mentioned, 
please),  I  simply  decided  to  say  noth* 
Ing,  since  f  had  nothing  to  say, 

I  don't  write  this  cotumn  to  feed  my 
ego  (corttrary  to  what  some  of  my  cfft- 
ics  say),  r  write  this  column  because  I 
think  ham  radio  ought  to  be  more  than 
chasing  DX  and  giving  out  signal  re* 
pofts.  I  think  hams  should  be  involved 
and  concerned  atx>ut  their  hobby  and 
about  the  world  ancHjnd  them.  I  try  to 
send  out  sparks  in  this  column,  and 
hope  that  at  least  one  person  will  give 
some  thought  to  whatever  topic  I  bring 
up.  I  don't  wan  I  you  to  agree  with  me. 
but  I  do  want  you  to  think  and  develop 
youf  own  opinion  aiiKXlt  tJ^ngs.  Jt  noth* 
ing  else,  I  hope  my  column  can  pro* 
vide  something  to  talk  about  during  a 
QSO,  other  than  the  make  and  model 
of  your  store*bought  rig. 

Amateur  Radio  Child  Search 

To  pick  up  where  we  ieft  off  a  few 
months  ago,  you'll  recall  that  I  re- 
quested those  of  you  who  were  Inter- 
ested in  assisting  in  the  formation  of 
Amateur  Radio  Child  Search  to  drop 
me  a  note  so  I  could  gauge  whether  or 
not  the  idea  could  get  off  the  ground. 

I  received  three  letters  telling  me 
why  \  shouldn't  even  try  to  do  this.  } 
think  you  can  figure  out  where  I  told 
those  naysayers  to  go.  I  received  a 
phone  call  at  my  home  on  a  Sunday 
affernoon,  and  the  caller  got  angry 
with  me  when  t  suggested  that  it 
would  be  more  appropriate  if  he  con- 
tacted me  during  business  hours  at 
my  office.  I  even  received  a  call  from  a 


high-level  employee  of  a  well-known 
national  service  organization,  outlining 
a  possible  funding  source  \  asked  him 
to  send  me  some  info  so  that  t  couki 
prepare  a  proposal  for  his  or^niza- 
tion,  but  he  never  did.  t  don't  have  this 
gentleman's  phone  number  (I  know, 
that's  my  fault),  so  that  avenue  turned 
imo  a  dead  ertd  (at  least  so  far).  TT^t 
was  disappointing,  because  a  single 
source  of  funding  would  have  made 
this  idea  an  Immediate  reatityH  I  was 
{and  am)  willing  to  do  all  the  organiz- 
ing worit,  travel,  and  whatever  else  it 
takes  to  get  this  going,  but  a  commit- 
ment o(  funding  from  a  major  organi- 
zation sura  wouHd  make  tl  a  lot  easier. 

When  you  take  out  the  flakes. 
kooKs  and  nuts,  I  received  approxi- 
mately 60  responses  from  people  all 
across  the  country,  pledging  their  sup- 
port. Over  100.000  people  cast  their 
eyes  upon  these  pages  every  mkonth 
(if  you  believe  the  research  that  Shows 
most  magazines  are  read  by  at  feast 
two  people).  Even  if  you  only  take  our 
paid  circulation  figures,  at  least 
50.000+  people  had  the  magazine  in 
their  hands.  Sixty  responses  out  of 
50.000  p&(^ie  is  not  what  I  woukj  caJt 
an  overwhelming  outpouring  of  sup- 
port. In  fact,  I'd  call  it  downright  em- 
barassing. 

To  those  who  responded,  I  regret  to 
telt  you  that  il  doesn't  look  like  thfs 
idea  is  going  to  get  off  the  ground.  I 
would  urge  you  to  think  about  formirig 
a  local  group,  or  making  it  a  club  ser- 
vice project  to  contact  local  law  en- 
forcement and  set  up  something  like 
what  I  suggested-  You  don't  have  to 
make  it  fancy.  Just  be  prepared  to  pn> 
Vkte  an  organized  ar>d  trained  search 
group  for  whenever  your  local  law  en- 
forcement agency  needs  it.  If  you 
need  my  help,  give  me  a  call  (at  my 
office,  please).  I  am  keeping  a 
database  o{  all  of  you  who  wrote  to 
me.  If  a  funding  source  does  present 
itsetf.  t'lf  be  in  touch. 

Out-of-Band  Radios 

My  column  on  the  use  and  owner- 
ship of  radios  capable  of  out-of-faand 
transmissions  generated  the  most  re- 
sponse of  anything  I've  written  in  the 
last  threfi*and-a-ha]f  years.  Unfortu- 
nately, the  reading  comprehension 
level  Of  some  people  isn't  what  it 
should  be.  Either  thai  or  many  of  you 
didn't  bother  to  read  the  whole  artJde 
(the  lact  that  the  dosing  parngraph  of 
my  original  text  got  chopped  off  with- 
out my  knowledge  didn1  help,  either)- 

Many  of  you  sighted  the  regulations 
giving  us  permission  to  use  any 
means  at  our  disposal  to  save  life  or 
property.  Many  of  you  simply  thought  I 
was  trying  to  confiscate  your  radios,  f 
got  accused  of  being  a  socialist  (which 


Continued  on  page  80 


Propagation 


Humber  29  on  your  fewtoack  card 


Jim  Gray  WIXU 

210  East  Chateau  Circle 

Payson  A?  8554 1 

As  I  write  these  words  (late  April),  the 
month  of  July  does  not  k>ok  partk^ulaity 
good  for  HF  band  propagatton.  There 
are  several  reasons  for  this:  generally 
declining  sunspoi  activity;  htgher  daytime 
absorption  of  signals  during  the  summer: 
probable  violent  magnetic  field  storms 
which  would  adversely  affect  the  iono- 
sphere, hence  Hf  band  propagation  dur- 
ing several  days  surrounding  the  10th. 
16!h,  and  29th;  and  possible  other  geo- 
physical events  such  as  hurricanes,  vol- 
canic eruptions  and  earthquakes.  That  is 
not  to  say  they  iv/W  occur,  or  that— if  they 
do — they  will  happen  in  the  U-S.A.  How- 
even  my  records  taken  over  a  perkxl  of 
ahout  1 6  yea  rs  indicate  a  very  high  prob- 
ability ol  such  events  taking  place  when 
the  sun*s  disturbances  cause  strong 
magnetic  field  disruptions  on  earth. 

On  the  positive  side  of  the  ledger,  it  is 
interesting  to  note  tl^t  when  HF  bands 
are  the  poorest  it^  VHF  bands  are  often 
the  t>est  ,  .  .  and  that  can  happen  durtng 
this  TTx>nth.  Theie  will  be  meteor  shower 
propagation  (delta  Aquahds  peaking  on 
the  29ih),  and  a  possibility  of 
strong  auroral  and  sporadic  E 
ionization  on  or  around  the  dates 
given  above.  Sporadic  E  propa- 
gation via  fast- moving  ion  clouds 
often  results  in  sfiort  contacts  on 
10,  6  or  2  meters  with  very  k?w 
path  loss  and  high  signal  tevets. 

The  band-by-band  situation 
looks  very  much  like  last  month's 
forecast. 


Jim  Gray  WIXU 

30  and  40  Meter  Bands 

fsiighttime  DX  between  local  sunset 
and  sunrise  ought  to  be  good- to-excel- 
lent on  days  marked  Good  (G)  on  the 
chart,  and  often  on  Fair  {f]  days.  Thun- 
derstorm activity  usually  abates  several 
hours  after  sunset,  but  QRN  will  ob- 
scure weak  signals.  Day  and  night  shori 
skip  will  occur  on  many  days,  with  day- 
time skip  averaging  up  to  1,000  miles 
and  nighttime  skip  up  to  2,000  miles. 
Beware  of  high  absorption  levels  around 
k^catnooa 

SO  and  160  Me^BtfKJs 

Forget  any  daytirrte  activity,  but  when 
conditions  are  Good  (G)  you  may  well 
discover  occasional  DX  at  night,  espe* 
cially  when  QRN  from  thunderstorms 
isn't  present.  There  will  be  few.  H  any, 
really  good  OX  contacts  on  160  or  aO 
during  July.  Shofi  skip  at  night,  however, 
can  be  pretty  good  out  to  about  1^000 
miles  or  so, 

Always  listen  to  WWV  arxJ  the  propa- 
gation forecasts  at  16  minutes  after  any 
hour,  when  up*!o-date  reports  of  Boul- 
der K  and  A  indexes  are  given  along 
with  solar  flux  readings. 


10  arKi  12  Meter  Bands 

Sporadic  E  during  daylight 
hours  on  many  Good  days  (G), 
with  strong  skip  signals  from  500 
to  1 .500  miles,  and  with  abrupt 
tefmir^ation  of  contact  as  the  ion 
doud  moves  out  ol  range. 

IS  and  17  Meter  Sands 

Good  sporadic  E  contacts  be- 
tween 300  and  1,300  miles  on 
most  Good  (G)  days.  Also,  you 
may  find  trans-equatorial  skip  in- 
to the  Southern  Hemisphere, 
with  decent  but  not  outstanding 
signal  strength. 

20  Meter  Sand 

Consistent  DX  to  most  parts 
of  the  world  on  Good  (G)  days 
during  daylight  hours,  and 
on  particularty  favorable  days, 
often  until  midnight  local  time. 
This  band  will  be  your  DX 
workhorse . 


EASTERN  UNITED  STATES  TO: 

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88  73  Amateur  Radio  Today*  July,  1^B4 


/ 


"What  a  great  fiefd  radio. 
Mobile,  too!  I  couldn't  afford     ^. 
an  HF rig  until  now," 


<m 


''What  a  great  price! 
Terrific  features,  high 
performance  -  and 
within  nny  budget." 


**Yaesu  did  it  again!" 


ii 


FT-840 

Compact  HF 
■fransceiver 

•  Direct  Digital  Synthesis 
{ODS) 

•  Frequency  coverage: 
RX:  100kH7-30MH2 
TX:  160-10  m 

•  IF  Shift 

•  1 00  Memorv  Channels 
(independent  TX/RX  per 
memory) 

•  Twin  Band  Stacking  VFOs 

•  FM*'  Repeater  Operation 
Automatic  10-Meter 
Repealer  Offset 
w/Selectab(e  CTCSS 
Encode 

•  CW  Reverse  Feature 

•  Choice  of  Two  Qptionai 
Antenna  Tuners: 

FC-10  Matching  Externa) 
Antenna  Tuner 

FC-800  External  Remote 
Antenna  Tuner 

•  Accessaries: 
Contact  your  Dealer  for 
full  detaJIs. 

•  Optional 


W10* 


MEtefl 


f  a  -p 


rffl*** 


vfo-* 


STAfiT 


SCAIJ 


CLAf 


^*» 


pbwt 


PHONES 


rjtic  ^^  pwfl 


Ml"? 


I    / 


sse 


cW/** 


aw^ 


iqcv. 


CL>" 


FI|KCTI0« 


—ZT      tfFOi^w 


•^^Q/W 


fAST 


M^VFO 


SH^Ft 


bano 


OOSW^ 


'■';3^'i^- 


,f  yoLiVe  trading  up  from  an  older 
rig,  but  have  a  budget,  you  want  the 
most  you  can  afford  in  top-notch  HE 

'     Tlien  the  FT-S40  is  for  yoiL  It's  right  on 
the  money!  Considering  a  mobile  HF  or 

4     fteld  radio  and  doubt  the  quality  and 
features  of  tiny  WV  rigs?  Then  the  FT- 
840  is  for  you.  It  won't  disappoint  you! 

Built  to  handle  rigorous  field 
operatioOt  the  new  intense  LCD  dbplay 
affords  sharp  \'isibility  in  bright  sun- 


light Die-cast  heat  sink  and  internal 
thermally  switched  fan  keep  the  IT-840 
running  cooL  iVIoduIar  design  circuit 
boards  ensure  operating  efificiency  — 
manufacturing  excellence  youd  expect 
in  much  higher  priced  radios. 

For  high  performance,  the  FT-840 
features  a  low  noise  front  end  that  uses 
the  latest  in  PliT  RF  amplifier  design. 
Two  DDSs  and  magnetic  encoder  for 
silent,  smooth  tuning  and  fast  switch- 
ing. Tv¥in  band-stacking  \TOs.  And. 


automatic  M-m  FM  (optional)  repealer 
offeet  with  selectable  CTCS&  Even  two 
optional  external  antenna  tuners  to 
customi;se  your  rig, 

Tbp  of  the  line  quality  and  features 
at  a  remarkably  tow  price.  Just  what 
youil  expect  from  Yaesu!  For  high-tech 
performance,  and  a  wealth  of  features 
that  won't  break  your  budget  ask  your 
dealer  about  the  n^-840. 


Performance  without  corfiprvmise. 


sv 


©  1993  Yaesu  USA.  17210  Eti wards  Road,  Cerritos,  CA  90701  (310)  404-2/00 

Sc^ciTicatlons  siibji^ct  to  change  without  notice.  Specif fcaUons  guaranieed  only  wilhin  amateur  bands,  Soirte  accessories  and/or  opllurs  are  standard  in  c&naln  areas,  ChecN' with  your  tocai  Yaesu  deafer  for  specific  details. 


NWOOD 


Spend  this  summer  vacation  with  the  radio  you  always  wante< 


Q 


TS-950SDX 


TS-850S 


□ 
□ 


TS-450S 


TS-50S 


Q 


TM-241A 
TM-733A 


Q 

□ 


TM-742A 


TH^22AT 
TH-42AT 


TH78A 


r 


with  great  deals  from  KenwoodI 


An  industry  first!  50-voft  MOS  FET  final  amplffier  and  DSP  for  superior 
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•  Optional  modules  for  28, 50. 220,  or  1200  MHz  •  Remote-mountabTe  front  panel 

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TOOUf  Ctl^JF^erS  PRESCTT  THE  COMPlETtO  COUPON  AT  THE  IlME  OF 
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HAJyg 

ADDRESS 


~l 


Please  check  model  purchased  &  discount 

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Coupon  offer  valid  May  20  throDgh  July  20, 1994 


KENWOOD  COMMUNICATIONS  CORPORATION 

Amateur  Radio  Products  Group 

P.O.  Box  22745. 2201  E.  Dominguez  Street 

Long  Beach,  California  90801-5745 

eCopfffglt  1994  KEnwoocT  Communications  Corpcmtiofi 
AH  ngfrts  rtservod 

94AIUH3&I7 


J