[Milsurplus] scr-287 integration question

[Jack Antonio]

Mike Morrow wrote:

> 
> 
> The sidetone output of the BC-375 is simply connected in parallel with the audio output of the BC-348.


When I did this, the feedback was severe, almost like the receiver was 
actually modulating the transmitter.


> coming out of the BC-375 on transmit would cover whatever audio was coming out of the BC-348, 


This is what I initially assumed, this is how the ATB and ARB works, 
there is no muting at all of the ARB, the sidetone from the transmitter
swamps out the audio from the receiver.

I will try the setting of the sidetone switch in the BC-375, I didn't 
think that would be an issue as with the receiver off, the sidetone 
level I was hearing was actually a little on the weak side.

> There should also be in the BC-348/BC-375 interconnection circuits a "NORMAL-MONITOR" DPST switch, 

Thanks for the details on the monitor switch, I wasn't aware of the 
sidetone connection.  Where is that information located?

On my SCR-274N setups, I do include a monitor switch, that opens the key
line to the receiver rack.  Not entirely stock, but makes operation a 
little easier, still have to turn the gain down quite a bit, and on some
frequencies the antenna lead needs to be disconnected from the receiver
to prevent overloading.

At this point, I'm going to swap another BC-348 into the set, and see if
I still have the same problem. This BC-348R is a de-converted set, and 
maybe I missed something in the de-conversion.


> Do you use the NORMAL-MONITOR switch in your set up,


When I tried this, it really didn't accomplish much, given the
problem above.

  is the BC-348 connected through the BC-375 such that its antenna is 
grounded on transmit,

Yes, but disconnecting the antenna from the BC-348 made no difference.

Thanks for the help

Jack

Jack Antonio WA7DIA
scr287 at sbcglobal.net