[Hammarlund] Update on SP 600 JX-17 BFO problem

[Bob Kulow]

I had the same situation and eventually gave up on trying to use the
original circuit.

What I did was taking a feed from the IF output on the rear panel,
padding it way down and sending it to an IC product detector
followed by an IC op-amp to bring the output level up to match
the diode detector's.  I took power for both chips from the cathode
of the 6V6.

I also replaced the BFO switch with a 3PDT toggle switch to switch
the audio from the diode to the op-amp.

It works quite well.  SSB is as good as any other receiver I've heard.
The existing long AGC time constant works well for SSB.

Yes, I know it's not hollow-state.  But, the chips don't show and it
meant a lot fewer under chassis modifications.  This setup can be
removed in an hour or less to make it original.

If you want a schematic, I never drew one and I'll have to pull it out
of the rack & draw it out.  Might take a while.

73
Bob WA2UEH