Ham Radio/Ham Radio CD-ROM (Emerald Software) (1995).ISO/news/inham07/925

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Subject: INFO-HAMS Digest V89 #925
To: [e-mail]

INFO-HAMS Digest            Thu, 23 Nov 89       Volume 89 : Issue 925

Today's Topics:
             ARRL  (Was Re: No more amateur radio fees?)
      From junk to a jewel - how I monitor while away from home
                     Mobile VHF (almost) Kilowatt
                           Planes and HT's.
----------------------------------------------------------------------

Date: 23 Nov 89 15:49:58 GMT
From: cs.utexas.edu!uwm.edu!ux1.cso.uiuc.edu!tank!eecae!cps3xx![e-mail]  (Usenet file owner)
Subject: ARRL  (Was Re: No more amateur radio fees?)

                                                             I wish the
                                 ARRL would
                                 use the
                                 whole line
                                 for their
                                 posts,
                                 instead of
                                 just using
                                 the right
                                 hand side
                                 of the
                                 screen.
                                 But who am
                                 I to
                                 question a
                                 bunch of
                                 bureaucrats
                                 who send
                                 form
                                 letters to
                                 their
                                 constituents
                                 that don't
                                 address the
                                 issues
                                 which said
                                 constituents
                                 raise.
                                 73.

In the rare case that original ideas   Kenneth J. Hendrickson    N8DGN
are found here, I am responsible.      Owen W328, E. Lansing, MI 48825
Internet: [e-mail]   UUCP: ...!uunet!frith!hendrick

------------------------------

Date: 23 Nov 89 14:46:19 GMT
From: att!cbnewsc![e-mail]  (Bob Parnass, AJ9S)
Subject: From junk to a jewel - how I monitor while away from home

x
                     FROM JUNK TO A JEWEL
           or How I Listen to My Home Radio Receiver
                     While Away From Home

                     by Bob Parnass, AJ9S

   One Saturday morning a few years ago, my wife Pam, N9HRZ,
   brought home 3 large gray steel relay boxes from a garage
   sale.  She didn't know what they were, but was sure  they
   were a "steal" at $5 apiece.

   My examination  brought  disappointment.   These  35  lb.
   "boat  anchors"  appeared to be something ripped out of a
   factory control system.  The outsides  were  filthy,  and
   someone had spilled oil inside of them.

   Pam sensed my unhappiness with her find, so  she  offered
   to  ask  her dad, KA9CAI, to sell these boat anchors at a
   hamfest so we could get back some of the $15.

   For a year, one box sat in my garage, and the other boxes
   two sat in my father-in-law's garage.


                        Junk Reexamined

   Each box had a large hinged door, protected  against  the
   weather  by  a  gasket.   On the inside was a thick steel
   panel with about 8 DPDT relays, a time delay  relay,  and
   several toggle switches.

   All relays were made by Potter & Brumfield, a  top  relay
   manufacturer.   Each had a 117 VAC coil, 10 amp contacts,
   and was in a high  quality  Amphenol  socket.   The  DPDT
   relays  were  enclosed  in clear plastic dust covers, and
   had neon bulbs and resistors wired  across  their  coils,
   which provided a visual indication of relay activation.

   Components were wired together neatly to 2 large Bakelite
   barrier (terminal) strips.  All interconnecting wires had
   terminals crimped on at the ends, so  a  screwdriver  was
   the only tool necessary to service the unit.

   Now for the challenge:

      - I wanted a way to listen to my home radio  receivers
        while  I  was  away from home.  Could this "junk" be
        converted into a remote receiver controller?

   I dreamed up a remote receiver scheme when  back  when  I
   was  presiding  over our club at Bell Labs which operated
   on a poverty level budget.  When the club telephone  line
   rings, our controller:

    1.  Grabs the phone line by placing a resistor across it
    2.  Starts a timer
    3.  Connects the audio output  of  the  remote  2  meter
        receiver  to  the  phone  line  through an old phone
        patch

   After the timer times out, the controller drops the phone
   line.

   We  had  originally  thought  of  modifying  a  telephone
   answering machine to serve as a controller, but our home-
   built controller proved cheaper and more reliable.


                       Time Delay Relay

   The plug in time delay relay was  a  DPDT  configuration,
   enclosed  in a yellow cover.  Instructions printed on the
   side revealed that the delay time was between 0.1 and  10
   seconds,  and  was determined by the value of an external
   resistor.

   Older delay relays use a thermal switch, which  heats  up
   over  time,  making  or breaking contact after reaching a
   given temperature.  Fortunately, my delay relay  employed
   more  modern  circuitry.   Inside  was  a printed circuit
   board with an actual  solid  state  timer.   The  current
   Newark catalog lists this relay at $45, socket extra.

   I wanted a delay adjustable between a few seconds and  an
   60  minutes.   Not  having  a  schematic  of the timer, I
   applied 117 VAC to the coil and probed the circuit with a
   voltmeter.   I  found  the capacitor that, along with the
   external resistor, determined the delay time.

   A much larger capacitor was needed for long  delays,  but
   wouldn't fit within the relay case.  I removed the origi-
   nal timing capacitor, and ran 2 wires from its old  loca-
   tion  to  an  external  220  ufd capacitor through a hole
   drilled in the case.


                   A Controller Takes Shape

   I rewired the relays, and mounted a rheostat to  set  the
   timeout  delay.  The addition of pilot lights, 1/4" phone
   jacks, and modular telephone jacks complete the construc-
   tion.

   The remote receiver controller at IHARC requires  use  of
   an  external phone patch to connect the telephone line to
   the receiver audio.  We currently use a deluxe patch made
   by Waters.

   Not wanting to tie up a phone  patch  for  my  home  con-
   troller,  I brewed up an interface to feed the audio out-
   put of a receiver to the phone line.  It used a capacitor
   and  600  ohm  transformer  salvaged  from a discarded PC
   board, and a varistor cut out from a  telephone  handset.
   The  varistor  clips  residual  voltage spikes that could
   appear on the telephone line  from  ringing  voltage  and
   damage the receiver.

   The 35 lb. receiver  controller  works  well.   The  only
   problem  to  date  is that the timer was unstable.  Some-
   times it timed out after 10 minutes, sometimes  after  20
   minutes,  sometimes ....  I replaced the timing capacitor
   with a better grade component.

   I use the setup to listen to a  home  scanner  while  I'm
   away from home.  The scanner is powered from an AC outlet
   which becomes live when the controller  answers  a  phone
   call.

   The controller also came in handy for monitoring the NASA
   frequencies on shortwave during Shuttle missions.  I con-
   nected the  controller  to  my  Japan  Radio  NRD-525  HF
   receiver and called it up from my office at work.

   During Hurricane Hugo, I set up the controller to monitor
   the  Hurricane  Net  on  20  meters and gave out my phone
   number to coworkers with relatives living in the affected
   area.   They  could call my home and listen to 15 minutes
   of hurricane news more  current  than  reports  available
   from the press.

   The "Junk to a Jewel" controller is  connected  to  spare
   phone  line.   I wouldn't connect it to my main telephone
   line without adding a  circuit  that  waits  for  several
   rings before grabbing the line.
--
============================================================================
Bob Parnass, AJ9S - AT&T Bell Laboratories - att!ihuxz!parnass [phone]

------------------------------

Date: Thu, 23 Nov 89 12:29:38 GMT
From: [e-mail] (Pat Davis kd9uu)
Subject: Mobile VHF (almost) Kilowatt

FYI.. I'm sure you've seen the adds for:

CCI, Communication Concepts, INC.
508 Millstone Dr.
Xenia, OH 45385

PH# [phone]   MC/Visa

They have parts/kits for a 300W VHF amp.. Not sure if it runs on 12V
or 24/28 volts.  Hey what's a few Db among friends??
I can't tell you if it's class C or quasi-linear.
I have nothing to gain by revealing this "secret"..  I DO NOT know the
people..  I have never built one.  I know, it's just not the same.
You want REAL POWER so you can stall all those new-fangled computer brain-box
controlled vehicles you are around, possibly your OWN :-)->--< .

KD9UU, [e-mail] 128.104.198.10



------------------------------

Date: Thu, 23 Nov 89 14:27:47 GMT
From: Pete Lucas 0793-411613 <[e-mail]>
Subject: Planes and HT's.

A metal-bodied airframe will act as a faraday shield, hence any RF radiated
outside the airframe will tend not to make it to the inside except by passing
through any non-metallic holes (windows, cockpit glazing).  The internal
avionics are therefore screened from much of the RF fields found outside the
airframe. However, any RF generated INSIDE the plane is confined, and cannot
radiate freely into space, so it hangs around trying to upset things!

Bear in mind that typical HF SSB airplane radios are able to put out
several hundred watts. I dont know how efficient the antennas on a plane are,
or how well they are matched, but i guess a fair amount of the RF actually
gets radiated. However, hoping that the avionics are RF-proof, and using
a HT/cellular phone is IMHO a risk. Electromagnetic compatibility and
RFI-proofing doesnt come cheap, and we all live in a world where cost-cutting
is a fact of life.  RFI-filters are often the first to be omitted when
building to a budget...!
                                  11111000             de G6WBJ

Please use the following addresses for reply:         +     \/Natural
                                                      +    \/\Environment
JANET: [e-mail]               +   \/\/Research
ARPA : [e-mail]             +  \/\/\Council
EARN : PJML%UK.AC.NWL.IA@UKACRL                       +  NERC Computer Services
AX25 : G6WBJ       {144.650MHz}                       +  Holbrook House
SPAN : STAR::"[e-mail]"     +  Station Road
PHONE: [phone]                                 +  SWINDON SN1 1DE
FAX  : [phone]                                 +  GREAT BRITAIN

------------------------------

End of INFO-HAMS Digest V89 Issue #925
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