[ARC5] AN/ARC-3 ?

[Michael Clarson]

Jim: I don't know about the ARC-3 rcvr, but the transmitter autotune would
retune the entire transmitter. All stages were ganged together, motor
driven and tracked, and there was a relay that sensed a TUNED condition.
--Mike, WV2ZOW

On Fri, Jan 22, 2016 at 1:13 PM, Jim Haynes <jhhaynes at earthlink.net> wrote:

> Some old war stories...
>
> In addition to the ARC-36 (16 channels) and ARC-49 (48 channels) the
> C.A.A. had a version with 24 channels.  All this was done by crystal
> switching, so I guess the multiple channels had to be close in frequency
> so that one tuning setting would do for all the channels in one crystal
> position.
>
> I believe the original aircraft VHF set was the English equivalent of
> the SCR-522.  And then the SCR-522 was a U.S. redesign but plug compatible
> with the English sets.  Four channels, as also the ARC-4 had, and
> early civilian VHF sets.  And the VHF sets in the ARC-5 family.
> Four channels gave you one for emergency 121.5, one for control towers,
> one for flight service stations, and one left over for some other purpose.
> Evidently there was seen to be a need for more frequencies, but not many
> more, by the time the ARC-3 was developed.
>
> Then the military was allocated the 225-400 MHz band, and were expected
> to clear out of the 108-136 MHz civilian aviation band.  The military
> had to furnish GRC-27 UHF equipment to the CAA/FAA so that the air
> traffic control system could communicate with military aircraft.  And
> the military was forbidden for a time from acquiring any new VHF equipment.
>
> I was at Edwards AFB 1960-1963, during that period.  I believe at that
> base at least we had got rid of the BC-640 transmitter and BC-639
> receiver that were the mainstay of WW-II ground stations.  We had a
> bunch of ARC-3 sets with third-pary AC power supplies to meet the
> ongoing need for VHF communication.  Part of the need was that we had
> a lot of contractor aircraft flying in and out, and they were civilian
> and thus carred only VHF equipment.  Another need was for emergencies -
> sometimes airliners make emergency landings at Edwards to take advantage
> of the long runway extension provided by the dry lake bed.  So we
> had quite a number of these 15 year old ARC-3 sets in daily use as
> ground stations.
>
> There was also some mission that required flying around Europe from time
> to time.  By then the standard civilian VHF equipment was frequency-
> synthesized and could operate on hundreds of frequencies at the turn
> of a dial.  And ground stations had set up on frequencies all over the
> civilian band - every tower having a different frequency, every other
> kind of communication facility using lots of frequencies (as they do
> today).  Since the only VHF equipment we were allowed to put in the
> airplanes was ARC-3 or worse, we had a big suitcase of crystals that
> we kept in the frequency manager's office.  The flight crew would check
> them out when they had to fly to Europe and check them back in at the
> end of the mission.  I guess they had to carry someone in the plane who
> could retune the ARC-3 when they needed to change frequencies - or maybe
> they carried multiple ARC-3 sets to get more pre-tuned frequencies.  I
> wasn't in on that part of the operation.
>
>
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