[MRCA] [Milsurplus] [MMRCG] Speculations on ground radios of the fifties

Wed Apr 29 19:53:09 EDT 2026

Interesting procurement history here on ARC-21, ARC-38, etc.

https://books.google.com/books?id=I3NaEkHwo6MC&pg=RA100-PA20&dq=%22an/arc-38%22&hl=en&newbks=1&newbks_redir=0&source=gb_mobile_search&sa=X&ved=2ahUKEwiZ1K24npSUAxXIKVkFHUYzLTAQ6AF6BAgLEAM#v=onepage&q=%22an%2Farc-38%22&f=false

Nick England K4NYW
Chapel Hill NC
www.navy-radio.com

On Wed, Apr 29, 2026 at 7:08 PM Jim Whartenby via Milsurplus <
milsurplus at mailman.qth.net> wrote:

> Nick
> I have the feeling that the 1951 contract date is way too early for
> production so it must be a contract let for R&D.  This would eventually
> deliver the first article for specification and environmental testing.  The
> 1956 date would be for actual ARC-38 start of production as I have a
> Collins ARC-38 preliminary service manual printed by Collins which is also
> dated 1956.
>
> I looked for the AN/ARC-38 in the Collins Signal and found nothing but the
> 618S-1 is listed.
>
> Looked in the Electronics Equipment Index, NAVSHIPS 92563B, circa 1963 and
> the ARC-38 is not listed.
>
> My gut feeling is that the SMO took much longer to develop which delayed
> the ARC-38 so the 618S-1 was sold commercially.
>
> Thoughts?
> Jim
>
> Logic: Method used to arrive at the wrong conclusion, with confidence.
> Murphy
>
>
> On Wednesday, April 29, 2026 at 04:06:40 PM CDT, Nick England <
> navy.radio at gmail.com> wrote:
>
>
> FWIW, ARC-38 is listed in the Navy Supply Office catalog with 1951 and
> 1956 contract dates. Navy BurAer listed as design cognizance.
> https://www.navy-radio.com/manuals/94200/94200.1a_9-5.pdf
>
>
> Nick England K4NYW
> www.navy-radio.com
>
>
> On Wed, Apr 29, 2026 at 4:32 PM Jim Whartenby via groups.io <old_radio=
> aol.com at groups.io> wrote:
>
> Ray
> The first airborne synthesized, fully automatically tuned, HF transceiver
> would be the ARC-21, made by RCA.  It is an AM transceiver or "double
> sideband" as RCA would describe it which was also capable of CW operation.
> It also used RCA designed mechanical filters, two as IF filters and one as
> the BFO oscillator for CW operation.  Perhaps this is the first use of
> mechanical filters in a military radio?  It does not use 400 cycle power
> as all of the servo tuning systems are DC powered.  It is capable of 100
> watts RF output over the frequency range of 2 to 24 mc with 500 cycle
> increments over all frequencies.  It was designed for the first jet bomber,
> the B-47 and it's support aircraft.
>
> Some five years or so later, SSB became the main mode for communications
> so in order to recoup the investment in equipment already on hand, the
> ARC-65 was developed.  This modification was done by replacing the
> modulator, power amplifier and reference oscillator with most of the other
> modules of the ARC-21 remaining with appropriate modifications.  With this
> successful experience, RCA was tasked with doing the same for the ARC-38.
>
> The ARC-21 is listed in JANAP-161 as is the 618S-1 but not the ARC-38.
> I'm not sure why this is so as it is my understanding that the ARC-38 was
> in development before the release of the 618S-1.  Perhaps the ARC-38 was
> only used by the Navy so it was not listed in JANAP 161?  Both are wired to
> accept the SMO, servo amplifier and 500ks oscillator, IIRC, so I suspect
> that both were in development concurrently by Collins.
>
> As for the Army not converting to SSB, weren't they more impressed with
> VHF FM?
> Regards,
> Jim
>
> Logic: Method used to arrive at the wrong conclusion, with confidence.
> Murphy
>
>
> On Wednesday, April 29, 2026 at 10:05:12 AM CDT, Ray Fantini via groups.io
> <rafantini=salisbury.edu at groups.io> wrote:
>
>
> Want to Thank Nick for posting the info on the R-808 and GRC-14, over the
> years have owned a couple of radios but never any of the GRC-14 family of
> components. Would assume that it's somehow a competitor of the GRC-19,
> R-392/T-195 but never as successful. The ARC-38, 618, T-195 and T-631 are
> all using the dual winding servo tuning systems along with 400 cycle
> Chopper / Discriminator systems for PA and Antenna tuning, maybe the first
> true Autotune system developed. Remember that allegedly autotune radios
> like the ART-13 and the like are only radios with mechanical presets where
> the servo radios like the ARC-38 have a true automatic tuning system that
> thru the use of discriminators can arrive at a solution for   PA and
> antenna resonance.
> Spent many hours learning the ways of the ARC-38 and 180 L tuners, dealing
> with phase relationships and mechanical conversions of small DC voltages to
> high AC voltage to drive system. Similar system on the T-195 and the 618
> family of SSB transceivers. The GRC-106 amplifier employes the same idea of
> discriminators and resonance balance but relies on the operator to be the
> motor.
> A weird quirk of the T-195 was that they pushed the capability of the
> autotune a little too far maybe and occasionally the radio would not
> achieve a tuning solution, I always suspected that this was a result  of
> attempting to do both PA and Antenna match in one stage. Don't know if
> that's the case or not. But looking at the design of the GRC-14, they may
> have resolved that issue. It's going to annoy and aggravate a bunch of
> people out there but just looking at the manual have to say that although I
> never worked on or used the GRC-14 it may be a superior set to the Collins
> GRC-19, but at least the GRC-19 is lighter than a GRC-14 and smaller too.
> GRC-19 sets were everywhere, least until the death of AM and still held
> out in RTTY ops until the GRC-106 came along but the GRC-14 appear to only
> have limited use and were quickly phased out as soon as SSB was adapted as
> a standard. Too bad no one ever reverse engineered the GRC-14 sets for SSB
> like the ARC-38A
> Another question would be why the ARC-38A happened ?  The basic ARC-38 was
> a groundbreaking autotune transceiver with its self-tuning , variable IF
> and mechanical filters. It was years ahead of anything else out at the
> time. But by the sixties everyone knew SSB was the way HF communications
> were going, and the 618T was still in development, so how did it happen
> that someone decided to do the huge conversion from AM to SSB? And why when
> it was a Collins design, did RCA get the job? I like how RCA would also
> paint over the front cover, so you would no longer see the big Collins logo
> or name.
> Also have to wonder why there was no attempt to re fit the R-392/T-195
> (GRC-19) for SSB? Once again just looking at the book think it would have
> been easy to re-work the GRC-14 stuff then deal with how densely things
> were stuffed into the GRC-19
>
>
> Ray F/KA3EKH
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