[Milsurplus] AN/ARC-38 and AN/ARR-41
antqradio at juno.com
antqradio at juno.com
Sat May 13 21:36:46 EDT 2006
> Jack wrote:
> I like these cold war sets. Although not nearly as large and heavy
> and oddly-constructed as the USAF's RCA-made AN/ARC-21 and AN/ARR-36
> combo from the same era, I think these USN Collins-made systems
> would give the RCA stuff some good performance competition. I
> wonder how RCA won the contract to convert the Collins RT-311/ARC-38
> to the Collins/RCA RT-594/ARC-38A. RCA must have gained the
> necessary expertise when it came up with the design converting the
> 145-pound barrel-shaped AM RT-128A/ARC-21 to the USB RT-400/ARC-65.
>
> Mike / KK5F
Mike
I think there is a lot more to this question and of course, there is no
simple answer.
First, the obvious goal of the design was to eliminate the radio
operator. All that would be required of the pilot is to throw a switch
or two, wait a few minutes and talk. The big bombers were traveling from
one theater of operations to another. Since crystal control of frequency
requires re-tuning by a skilled electronics technician, a new approach
was needed.
The ARC-21 was the first synthesized HF multi-channel AM radio that I am
aware of. No one had designed anything like this before, so there was no
heritage to guide the design. It was unexplored territory. Also, the
contract for the ARC-21 must have been very early. Either during or just
after World War Two. It is the 21st ARC designated radio just as the
first Collins synthesized radio to cover the same frequencies is the 38th
in the line.
Just like the UHF ARC-27, the HF ARC-21 is in a pressurized case. This
must have been a contract requirement. I am pretty certain that the RCA
designers didn't take a vote on this! The same can be said for all of
the 28 VDC motors in the ARC-21. No 115 VAC 400 cycle power was
specified in the contract.
The guys at Collins had the benefit of knowing all that didn't work to
specification and, most likely, another 5 or so years to develop another
approach. As you are aware, the later move to SSB made both designs
obsolete.
It is interesting that the upgrade of the ARC-38 to SSB was done by RCA
and not by Collins. I can only guess that since RCA was a larger company
then Collins, they had the manpower to do the design and rework required.
Collins might have had enough to do with the contracts they already had.
As for the expertise, I would think that both companies had the best
engineers that money could buy. As for designing on the technical
cutting edge, I believe that the ARC-21 is the first radio to use the
mechanical filter. I think it has at least two in the IF!
Regards from Arkansas,
Jim
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