[Milsurplus] Re: ARC 65 tidbits

[BOEING377 at aol.com]

In a message dated 11/19/2004 4:31:19 PM Pacific Standard Time, 
milsurplus-request at mailman.qth.net writes:

> The ARC-65 was 
> basically a "throw everything out from the ARC-21 except the case and 
> stuff it with a new radio set."  My case still has the ARC-21 
> nomenclature plate on it.
> 

There was an article in the IRE (predecessor of the IEEE?) Journal about the 
ARC 21 AM to ARC 65 SSB conversion. There was a LOT in common between the two 
sets, some modules were apparently not touched at all. The ARC 65 used a BIG 
mech filter for SSB, more than twice the size of what Collins used in their 
sets of comparable vintage.
One odd design quirk, the ARC 65 transceiver was 99.999% DC, just HV LV and 
28 VDC except for one tiny bias transformer that took 400 hz. None of the many 
motors were AC, no selsyns or synchros, just that one transformer requiring 
AC. Frequency selection switching was done by using motors to match resistances 
between the control head switch positions and the on board counterparts in the 
transceiver. They used a big wire wound precision resistor on each switch, 
tapped for each switch position. The ARC 65 transceiver had a vibrator on one of 
the modules so some chopping was being done. The UNIVAC ERA antenna coupler 
is a physically beautiful unit on the inside, gleaming silver varicoils, copper 
vacuum variable, lots of 400 hz AC servo motors and synchros. 1950s 
electromech engineering at its best. No AN ARC anything, just ERA on the coupler, what 
numbering system does that fit into?

As far as output power, I always thought the ARC 65 beat the 58, but perhaps 
I was wrong. I think the 65 put out 400 watts PEP using two 4CX250Fs. 

Mark