[Milsurplus] RE: Nutso (RE: WW2 B-29 VHF radio?)

[aGEnuine ham]

Robert:
I got the drift that Marty was specifically refering to the use of
separate mixers (and rf) for the guard channel.  IIRC, and it has been a
long time, the later receivers either used a simpler, but less sensitive
technique, or a whole separate receiver.  Your reference to the
schematics will save us there.

I should remember the exact reason that the dual mixer scheme has a
better noise figure than other methods of dumping 2 channels into a
common IF, but it has been too many years.  When I was at GE Mobile radio
over 40 years ago, we produced a version of the 25-50 MHz receiver dubbed
"Simultaneous Monitoring", which used the dual mixer technique to produce
a receiver which listened to two different rf channels with the same
sensitivity as individual receivers.  Something to do with phase
incoherence of the noise into the IF.

George W5VPQ
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