[Milsurplus] VHF frequencies, AN/ARC-3

[jhaynes@alumni.uark.edu]

While we're on the subject, might as well mention that the ARC-3 had
a couple of derivatives.  ARC-36 is a 16-channel model and ARC-49 is a
48 channel model.  In these the basic 8-channel structure was preserved,
but you could have two or six crystals in each of the 8 channel positions.
(which meant that the two or six channels had to be pretty close together
in frequency, since there were only 8 tuning settings).

There was a period of time when the military prohibited acquiring any
new VHF equipment, as a way of accelerating the conversion of all
aircraft to UHF.  In the U.S. this meant equipping all the FAA flight
service stations with UHF equipment so that military aircraft could talk
to the air traffic control system.

It was a fairly boneheaded prohibition.  I was at Edwards AFB during the
time.  We had lots of civilian contractors flying in and out of the base.
All their aircraft were VHF equipped.  So we had a bunch of ARC-3 sets
with AC power supplies to enable us to provide air/ground communication
with the civilian aircraft.  There was also a military mission that came
up occasionally that involved flying all over Europe.  For this we had a
suitcase full of ARC-3 crystals.  Whenever they needed to change
frequencies from the eight channels already set up somebody would have to
change crystals in the radio, in flight.

I was pleased to see recently that the AF now has nice little radios that
cover all the VHF and UHF aviation frequencies.