[Collins] [AMRadio] 75A2 SSB ??

[Dr.Gerald Johnson]

I have a little box much like that described. Has a plug in mechanical 
filter. Built by W0PFP. I can't ask him about it, he's not talking. I didn't 
find anything about it in his files. I'm sure I could make a schematic of it 
in an evening if I set down to it.

To find such published, I'd look in Bill Orr's Editors and Engineers Radio 
Handbook dating from say 1950 through 1965. Then I'd look through 
QST and CQ, as well as 73 and ham radio magazines for that same 
era.

Basically the circuit should include probably one IF stage to make up 
for the filter loss, a product detector, BFO, and audio stage, probably 
some audio derived AC. The BFO can be arranged to switch from one 
side to the other, though it can be a mixer to another IF frequency 
with mixing frequencies selected to put either USB or LSB as USB at the 
product detector with a fixed BFO.

At the same time, converting the BFO stage in the radio to a product 
detector has been documented for the A line, 51J, and R-388 and 
R390(a). That depends on the IF of the radio providing adequate 
selectivity for SSB which can be helped by adding a mechanical filter.

73, Jerry, K0CQ, Technical Advisor to the CRA
-- 
Entire content copyright Dr. Gerald N. Johnson, electrical engineer.
Reproduction by permission only.