[R-390] Lankford AGC Mod ?

[Roger L Ruszkowski]

I understand the Lankford AGC mod to be two diodes in the AGC
circuit and a cap change to allow more BFO insertion into the
detector.

I understand what happens when we inject more BFO
into the mixer (detector) circuit.

I do not understand how the diode mod causes the
difference we do hear in single side bans signals.

How does that circuit work?
What is the difference in AGC action of the circuit?
Why does SSB sound better with the change?
What caps should we experiment with to give better time constances?
What would be some target values for those caps?

Other than exceeding the PIV or forward current load of
the diodes does the choice of diode make a difference?

Is diode linearity critical for this circuit?

Is diode switching time critical for this circuit?

I know this is all available some where.
Does some one have it handy and can you
send me some clues.

Thanks

Roger KC6TRU