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

[David C. Hallam]

The break in relay on the R-390 only grounds the antenna input and does 
not mute the receiver.  What you have to do is open the RF gain 
connection on the back panel strip.  I did it with a relay.  On transmit 
you ground the R-390 break in relay and open the relay in the RF gain 
circuit.

David
KW4DH

On 7/24/2011 10:42 AM, frankshughes at aim.com wrote:
>
> 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
>
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