"Jon Teske" wrote in message
...
On 25 Jan 2009 12:50:41 -0500, (Scott
Dorsey) wrote:
George McLeod wrote:
Would anyone have a circuit, or know where to find one,
for the Conelrad
device as marketed by Motorola and Heathkit.
What is this device? Does it automatically tune the radio
to a CONELRAD
frequency?
--scott
I lived in this era. Back in the 1950's there was a
program called
CONtrol of ELectromagnetic RADiation. Subtitled CONELRAD.
All AM
radios (FM was in its commercial infancy, we only had
Public Stations
in the FM band) had little triangles with the Civil
Defense logo at
640 Kcs and 1240 Kcs. [Kilocycles (per second) here is not
accidental,
Hertz, as a term to mean cycles per second, was not
adopted until the
mid-1960's.] In the event of an emergency, usually
interpreted to be
an attack upon us by the Russians (this WAS the McCarthy
era after
all) you were supposed to tune your AM radio to one of
those two
frequencies for information on what to do. Inplicit in
that was that
all other radiostations would get off the air so that they
could not
be used as homing devices for attacking aircraft. The
fact that there
were other methods to navigate was blithely ignored.
About 1957, CONELRAD was expanded to include amateur radio
stations
and all stations were obliged by the FCC to have a
CONELRAD monitor
which would tell you that an emergency was declared, that
you were to
get your own station off the air, and like the rest of the
population
tune to 640 or 1240 AM.
This ruling was more observed in the breach than the
observance. And
few amateur stations did anything about it. [My
response...I was a
teenager then...was to look for a mushroom cloud. If I saw
one, I'd
get off the air. :-)
A few companies built add-on CONELRAD monitors. If I
remember
correctly, you attached the device to an ordinary AM radio
which was
already and always tuned to 640 or 1240 Kcs. (1240Kcs.
actually
happened to be the frequency for the station in my own
hometown in
Wisconsin.) When some keying signal came on, the CONELRAD
monitor
would alarm and then you were to get off the air. It
didn't retune any
radio to anything, it just told an alert went off as
broadcast on one
of those two frequencies...at least that was all a ham
version did.
In theory, you could just have a small radio playing in
the background
which supposedly would tell you the same thing.
In actual tests, which were conducted from time to time,
just as
Emergency Service Tests are occasionally heard now. All of
a regions
stations got on one of those two frequencies (to confound
the enemy's
direction finders) and they had some sort of switching so
that they
all broadcast the same message from "Big Brother" but
broadcast them
in some sort of rotation. The few tests that I actually
heard knocked
our local station off the air, but the "emergency"
broadcast itself
was total gibberish because there were too few stations in
our rural
part of Wisconsin by day, and nighttime propagation was
too screwy to
provide any responsible path.
I don't remember when CONELRAD died as I went off to
college in 1960
and wasn't on the air very much and not at all when I was
in school.
It was dead when I got back on the air with any regularity
after I had
graduated..
Heathkit did indeed built such a monitoring kit. It was in
the same
size box as their famous QF-1 Q mulitiplier or their
earliest SWR
in-line monitor, one of the first with a Monimatch
architecture. It
cost somewhere between $10 and $20 as a kit IIRC, but that
was too
much allowance money for me to spend. Even as a teen, I
had a keen
sense for Governmental BS (which paid off well later as I
was a career
Federal Employee for 35 years in the intelligence world.
You needed a
steep skirted BS filter to work in that environment.)
CONELRAD was one of the biggest governmental flops ever in
the
communications arena.
Jon W3JT (K9CAH back then.)
CONELRAD was inspired by the supposed fact that the
Japanese aircraft that attacked Pearl Harbor used a Honolulu
broadcast station to home on the target. Conelrad required
all broadcast stations to leave the air during an alert and
certain stations switched to 640 or 1240 Khz, depending on
which was closer to its normal frequency, and operated with
low power. All ham stations were supposed to leave the air.
The stations switched among a group to cause RDFs to become
confused, at least that was the idea. All stations were fed
with the same audio, which originated at the key station of
the group via a telephone network. My memory is that all
stations had monitors tuned to the key station which were
tripped by a tone of some sort. In Los Angeles KFI was the
key station with KMPC (710) acting as back-up when KFI was
off the air. Because of its function as the key station KFI
began broadcasting twenty-four hours a day except for a few
hours on Sunday nights for maintenance, during which KMPC
stayed on the air.
There was, I think, only one nationwide test, and a few
local tests. It was quite possible to identify some of the
individual stations by their sound and the key station could
be identified by the higher audio quality. The system was a
failure but contributed to the general panic about a
possible Russian neucular attack. A lot of people were
convinced that a Russian attack was inevitable and there was
quite a scam going at the time among contractors who offered
to build bomb shelters in your back yard. I wonder how many
of those bomb shelters still exist.
I did a Google search after writing all this and found a
couple of good sites:
http://en.wikipedia.org/wiki/CONELRAD
http://www.oldradio.com/current/bc_conel.htm
--
--
Richard Knoppow
Los Angeles
WB6KBL