[Milsurplus] ARC 21 ARC 65

[boeing377 at aol.com]

"I have seen a few ARC-21 transceivers.
Some had a vacuum variable in the PA, others had 
a open vane variable enclosed in a plastic container, oil filled.
The tuning was done by upsetting a balanced bridge.
When a new frequency was selected, the bridge 
would be rebalanced by 400 cps servos.

Could have been a servicing nightmare.

73
Glenn
WB4UIV"

I never saw an ARC 21 but my ARC 65 had no 400 Hz servo motors. Not one. Everything that moved was 28 VDC. 

There was a 28 VDC vibrator chopper to give chopped DC where needed for servoing. 

Was the 21 that different from the 65?

The 65 had one curious 400 Hz component inside the RT barrel. It was a small bias transformer. But for that xfmr you could have run everything from 28 VDC using the dynamotor set. 

The ERA coupler had all 400 Hz servo motors. I gave away my RT 400 ARC 65s but still have the coupler. It is a beautiful thing to look at when taken out of the pressure housing. One of these days after I retire I might get the coupler running just for fun. 

73
Mark
AF6IM
www.parachutemobile.org