[R-390] Collins R-390 muting

[Roy Morgan]

On May 13, 2009, at 9:42 PM, Patrick wrote:

> David, thanks for your response, but grunding pin 9, only picks the  
> antenna
> relay on the R-390, but does no mute it. How do I mute the receiver y
> addition to removing the antenna input from it?? .... Pat

Grounding pin 9 should do two things:

- operate the antenna relay (or de-energize it, I can't remember  
which). I THOUGHT that this would disconnect the antenna input coils  
from the rear panel connector and ground them, but the schematic I  
have from TM-11-5820-35 shows that it only grounds the antenna  
connection. This may be less than fully effective if the relay is not  
making good contact.

- operate the braak-in relay which grounds the first audio amplifier  
output to both line and local audio sections. THIS should "mute" the  
receiver, though the whole receiver is still operating with the  
antenna connections grounded and the audio signal grounded.

The RF/IF gain line is brought out to a rear terminal strip  
connection:  TB-102 terminal 1.  Normally this is jumpered to terminal  
2 which is the "top" end of the RF gain control.  If you break that  
connection with floating relay contacts, the radio will mute.  If you  
insert an additional potentiometer (5K should do), you can adjust the  
"muted" gain of the receiver to a convenient level so you can monitor  
your own signal.



Roy

Roy Morgan
k1lky at earthlink.net
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Groton NY, 13073
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