[Milsurplus] ARC 65

[boeing377 at aol.com]

I used to have three of these ARC 65 beasts. Got one working on receive only using a CQ article written by Gordon Elliott White as I recall. It?had a great rcvr, very sensitive and quiet. AM CW and USB only. It had a huge mech filter for SSB. The aircraft control head only had 20 pre selected freqs using moveable pins for each channel. Interestingly, the TEST SET control head had full range direct frequency selection without codes (ARC 38 used codes). You could select any freq directly from rotary decade dials. I once saw an ARC 65 with the full freq test set control box installed in an aircraft. it was?at a museum, the USAF Museum in Dayton as I recall. If my memory is correct it was a Presidential VC 118 (DC 6). The big barrel xcvr was still in the plane too all cabled up and ready to go.



Ready to go is a misnomer. My ARC 65 was always having problems. Tarnished contacts on rotary switches was a constant problem, probably made worse by the fact that I did not pressurize my RT 400 ARC 65 xcvr?"beer keg"?with dry nitrogen as per USAF spec. It had a master mechanical power "buss" a shaft that wound its way through everything. Various modules tapped into the "mech power buss" as needed by means of 28 VDC clutches. It also had a lot of small gear motors doing various tasks, all 28 VDC. It was ALMOST a pure DC xcvr (no selsyns, no AC motors) except for one exception, it needed a tiny amount of 400 hz power for a bias xfmr. Very odd.



I spoke with someone who flew on KC 97 tankers that had ARC 65s. He said they were very good radios when working, but had a lot of down time.? The ERA antenna couplers, however, ?were?more reliable. I always wondered why the couplers (made by UNIVAC) didnt have a standard nomenclature, they were just labeled ERA.



Somewhere buried deep in my archives I still have an ARC 65 and ARC 21 tech manual, ARR 36 and ERA manuals too. I kept the ERA, it is such a beauty inside and possibly could be restored to operation with a modern HF xcvr using? 100 VAC 400 hz power for the ERA coupler.



I used to work for Hughes Aircraft. We got a USAF RTTY evaluation contract which allowed us to?compare the performance of the ARC 58 and the ARC 65 for airborne RTTY. Hughes?used a USAF C 131 (Convair 340) that flew all over the western hemisphere for the tests. It had both the ARC 58 and ARC 65 installed. The ARC 65?consistently ?beat the ARC 58 on all counts. The Collins folks wont like this but the RCA ARC 65 had a better rcvr than the ARC 58. Hughes made the RTTY modem.



There is a very complete tech article on the ARC 21 to ARC 65 conversion in one of the old IEEE (or IRE) journals. It was written by an RCA engineer.



73,

AF6IM