TerryJ wrote:

I am considering adding a product detector to my S40A. Has anyone used a
6SN7 to replace the 6J5 BFO and feed the IF signal to the grid of the second
triode with the cathodes tied together? The original oscillator circuitry
would be wired to the first triode. Audio from the plate resistor of the
second triode (after IF filtering).

I'm sure its been done but the question is why would you want to?
Ok, its fairly deaf on 20 SSB and really deaf and getting quite unstable
for SSB on 15. Forget 10. Its more than adequate on 40 and 80 if you
ride the controls the way you should. I don't see where a product could
offer any improvement.

-Bill