[R-390] Break In

[Flowertime01 at wmconnect.com]

Collin,

Break-in opens the antenna input relay and opens a circuit in the audio path 
some where after the diode load.

It depends on how much RF the transmitter radiates around the shack to the 
receiver and how much RF is radiated across the open relay contacts in the 
receiver.

Also you now have the external amp subject to RF exposure.

You should be able to operate the receiver break-in relay from the 
transmitter keying circuits.

The receiver audio as heard in the speakers should then be reduced to just 
the noise of the receiver and amplifier. The RF from the transmitter should be 
at a low level that does not radiate into the receiver and amplifier to cause 
sonic howls. If the transmitter when keyed is causing more audio output than 
just the noise level you have if you short the break-in terminal on the receiver 
to ground then you need to get some shielding between the transmitter and the 
rest of the equipment.

If you want the audio to mute when you go to break-in, then you will need a 
relay between the Diode Load output and the external amplifier. You will need 
to devise your own power source and keying circuit for that extra relay. Once 
you get that taken care of you then have to consider how badly the audio pops 
as the relay goes from passing audio, to open circuit, to grounded input as the 
relay switches. There will be another pop as the relay comes out of break-in. 
Many audio circuit things to think about as you make improvements to you 
stations operation.

But then it is winter and time to work on these problems as you hug your warm 
glowing equipment.

Roger AI4NI   </HTML>