[Milsurplus] Conelrad

[Dick]

WOW!  CONELRAD really takes me back!!!

It's an acronym for CONtrol of ELectromagnetic RADiation.

Where I grew up, it was tested every other month.  Modulation was
an audio tone (I forget the frequency) and you could hear clicks on
the 640 and 1240 KHz frequencies as the signal emanated from one
XMTR after another.  The concern was that AM broadcast stations
are fixed in one location and could be used as homing beacons by
an attacking bomber force (at that time, the Soviets were the main 
concern).  The lower XMT power also reduced the useful range of
the stations that might be used as homing beacons.

Following the development of reasonably accurate inertial navigation
gear, it was generally thought that CONELRAD was no longer useful
as a defense system and it was decommissioned.  Then came the EBS
and, later, the current EAN systems.

Ah, those were the days...when lots of people worried about "The
Bomb" and built shelters in their basements.

73,

Dick W1NMZ

----- Original Message ----- 
From: "Ray Fantini" <RAFANTINI at salisbury.edu>
To: <milsurplus at mailman.qth.net>
Sent: 01 December, 2005 06:49
Subject: [Milsurplus] Conelrad


This is not exactly mil radio related but it is radio. For the last
several years I have worked part time for Clearchannel radio as a
transmitter engineer. over that time I have had to rebuild three
different AM sites and this included replacing old Gates ( Harris)
transmitters of the BC-5 (5Kw) and BC-1 (1Kw) series. all of these
transmitters were from the late forties and early fifties and were
equipped with the dual crystal selector for the second "Conelrad"
crystal. Asked a couple of the old timers around here and no one
remembers for certain if their were any occasions where they actually
tested the system, their is some speculation that once a year or so they
would do a national test and everyone would switch to that channel then
but that would be a test with no audio, but the question I have is if
you had to operate on the Conelrad channel don't think you would have
much output unless your regular broadcast channel was close to the
Conelrad channel. The narrow tuning range of the transmitters and
antenna tuning networks would probably give you only twenty or thirty
watts or so, and all the old transmitters I have seen have no provisions
for a second set of networks for Conelrad. Its amazing how almost all
the people working in broadcasting now have no idea that this system
ever existed, many don't remember the EBS system and the red
authenticating envelope or how you were not allowed under penalty of law
to open the envelope before it expired. and last but not least everyone
has heard the story of how the Japanese were able to receive the AM
broadcast from Hawaii and possibly use that for tracking towards Pearl
Harbor, but is their any evidence that the Russians twenty years later
would have used commercial broadcasting for target location? would have
thought they had systems more advanced then that?
Ray Fantini KA3EKH
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