{Collins} WTB, and general info needed re: 75A-3



Hello all,

I'm new to this list, and will be new to the CCA shortly.

I recently re-discovered an old Collins 75A-3 receiver that I purchased
when I was 12 at a Hamfest, and am getting back into ham radio (Need to
re-apply for my expired license).  Anyway, I have a good lead on a KWS-1
transmitter, and I already have the 75A-3, which I have replaced all of
the tubes, and it is in perfect working order.  As far as I can tell, the
only piece missing in order to have the complete setup is the SC-101.
Does anybody have an extra hanging out in their garage they would be
willing to part with?

Also, there was a modification to my 75A-3 that I am trying to identify.
On the front panel, a phone jack was added just above and to the left of
the CW limiter, and a small two position toggle switch was added between
the meter and the frequency scale.  The switch seems to connect to the
CW-AM-FM switch, and a board with 7 capacitors on it.  The switch reverses
the polarity of the capacitors in the circuit.  I'm not sure where the
wires go from there, because I haven't removed the front panel yet, but
there is also a BNC plug on the back that has been labeled "455KC IF
Output" and the screw connector normally labeled "P" (Next to the audio
connectors labeled "G" and "4") has been labeled "Detector."  Last but not
least, there is a UHF female connector under the serial number labeled
"455KC IF Input."

Any ideas on what the modification is, and if I should remove it and
return the receiver to its original schematic?

Thank you,

Justin A. Kraft
Sponsored by the Collins Collectors Association http://www.collinsradio.org
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