[ARC5] Info for VHF Transmitter

[Mike Morrow]

I have no documentation on the T-21, but I know some things about it.

It is nothing more than a T-11A 116 to 132 MHz transmjtter with an auxiliary shelf inserted at the back that plugs into the T-11A five crystal sockets.  On this shelf are two banks of five crytal sockets and one relay that selects between banks.  Two wires run from this relay to power and to an existing front panel connsctor pin.  This shelf therefore doubles the T-11A five channels to the T-21 ten channels.

It should be trivial to find the pin connection that must be grounded to switch crystal banks.  Every other part of the circuit will be identical to the T-11A.

The A.R.C. Type 12 gear first appeared for military and commercial markets in 1947, and is unrelated to the AN/ARC-5 except for some borrowed but highly-modified receiver designs.  Some stayed in service on secondary aircraft for a long tjme, like the sets on T-34B trajning aircraft at NAS Corpus Christie in 1972.  The T-21 would have been sold to commercial markets in the mid-1950s through early 1960s.

Good luck.

Mike / KK5F

-----Original Message-----
From: Cliff Miller 
Sent: Jul 1, 2017 12:20 PM

Just bought an A.R.C. VHF transmitter marked T-21.  There is no mention of "ARC-5" on the label.  It has four 5763 tubes so must be similar in design to the T-13A of the Type 12 radio set except it has 10 crystals instead of 5.
Any info or assistance in identifying this radio would be appreciated.  I haven't found any manual or schematic or article on a transmitter with this designation.
My application for this is to pair it with an R-508 I have running.  I have that cabled up to an old control box using information on the R-19 from my Type 12 manual.  That works fine to monitor air traffic passing by, LOL.
My theory is that both of these are 50s radios rather than WW2, that these may have been civilian service products.  
Another orphan I've adopted is a single receiver C-22A control box for which I've found no information, either.  It worked with the R-508 in a fashion, except the volume control worked backwards (counter-clockwise = louder).
Thanks!

-- 
Cliff Miller W4HGR
cliff52 at gmail.com