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

Thu Apr 30 09:52:58 EDT 2026

Jim,

The ARC-21 in the B-47 was installed on station 861 that is right after the rear wheel well.  In the first prototypes, it was installed at about station 1166.  The radio and the dynos where moved to station 861, but the coupler stayed at station 1166. 

Best, Francesco

From: milsurplus-bounces at mailman.qth.net <milsurplus-bounces at mailman.qth.net> On Behalf Of Jim Whartenby via Milsurplus
Sent: Thursday, April 30, 2026 2:18 AM
Cc: mrca at mailman.qth.net; milsurplus at mailman.qth.net
Subject: Re: [Milsurplus] [MMRCG] Speculations on ground radios of the fifties

Nick

Yes, I have the same report which is dated 29 July 1954.  Per the report on page 20, the ARC-26 program was cancelled in 1952 and a new contract for the ARC-38 was then awarded.  So I don't understand the ARC-38 first contract with a date of 1951.  It couldn't have been for production or even a study program since the ARC-26 contact was still valid at that time.  This is why I said that the 1951 date was too early.  Of course all of the testimony made in the congressional report could have been from memory of events that happened about three years previously.  Don't really know, I wasn't there.

There are misunderstandings on page 4 which mentions approximately the same information as that on page 20.  It mentions that the 618S-1 was being procured in lieu of the ARC-21.  I don't see that as a possibility since the 618S-1 does not have the ability to operate at 50k feet or have the frequency synthesis to allow more then 144 channels.  The 618S-1 could have been used for a time on support aircraft for refueling in flight to free up additional ARC-21s to be installed in the B-47.

I think that most of the bad press and reliability issues about the ARC-21 has to do with it's location in the B-47.  It was mounted in a rear compartment at about where the vertical stabilizer leaves the airframe body after the rear landing gear.  In this location. the temperature can go from 100 degrees on the tarmac to -55 in at 55k feet a matter of a few minutes.  Not to mention the shake, rattle and roll of being in a compartment exposed to jet engine noise.

Regrds,

Jim

Logic: Method used to arrive at the wrong conclusion, with confidence.  Murphy

On Wednesday, April 29, 2026 at 06:53:25 PM CDT, Nick England <nick at navy-radio.com <mailto:nick at navy-radio.com> > wrote: 

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

https://books.google.com/books?id=I3NaEkHwo6MC <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> &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 <http://www.navy-radio.com> 

On Wed, Apr 29, 2026 at 7:08 PM Jim Whartenby via Milsurplus <milsurplus at mailman.qth.net <mailto: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 <mailto: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 <http://www.navy-radio.com> 

On Wed, Apr 29, 2026 at 4:32 PM Jim Whartenby via groups.io <http://groups.io>  <old_radio=aol.com at groups.io <mailto: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 <http://groups.io>  <rafantini=salisbury.edu at groups.io <mailto: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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