[R-390] break-in question, 390A and 390

[frankshughes at aim.com]

Hi,
I am seeking advice on break-in function and troubleshooting audio.


I have a Collins 32S-3 transmitter, and am trying to use either a 390A or 390
to receive.


I have deduced that the relay logic for the 32S-3 (Open w/ PTT) had to be reversed 
to work with the "break in" contact on the 390A and 390 terminal strip (N.O.)


So I put a relay in the circuit between the 32S-3 and 390, works great. 


The ohm meter shows that when I PTT the 32S-3, the 390A and the 390
antenna input center pin goes to ground, and the audio also squelches to full quiet.


However, I get lots of audio output from the 390A and the 390 when I speak into the mic!!! 


So even though the antenna input is grounded, both the 390A and the 390 are still getting 
signal input. 


The audio is also present from the 390 and 390A if I disconnect the antenna and activate break in
while keying the 32S-3. 


Is the 32S-3 bleeding RF into the shack the 390 and 390A can pick up even with the antenna disconnected? 
(How can these things be so sensitive to tiny RF levels...oh, wait....)


If so, building a Faraday cage around my transmitting position would be ....crazy.....OK, plan "B" is to
put a relay into the audio circuit to open the input to the speaker at the same time PTT is activating
break-in. 


Or what else can I do????


Thanks,
Frank
KJ4OLL