[Collins] E. F. Johnson T/R switch

[Smith Bradford]

Has anyone tried to incorporate the E. F. Johnson T/R switch into the 
Collins S Line series 3?  The goal is having true break in keying. In 
experimenting  with the idea I have run into a problem with hearing the 
tone oscillator until  K1 drops out. The result, is after you let off 
the cw key, you hear the tone generator at low level, then the K1 drops 
out and you hear the receiver audio.

I currently don't see any practical way to prevent this. I have no 
intension's of making major modifications to the S Line. And the tone 
generator is doing what it is suppose to do in cw, that is key the K1 
relay via the attached triode and provide cw sidetone. I removed the cw 
sidetone cable from the receiver but the tone generator is still audible.

I am curious how the 750 cps tone generator is making it's way into the 
audio path to the speaker. I defeat the receiver mute by place the 
receiver function switch in the operate position instead of the normally 
used standby position. The only other path I see is the tone generator 
going into the balanced modulator. But during cw operation the rf signal 
doesn't pass through the balanced modulator.

Smith Bradford
W9HAK