[R-390] 390A Audio Deck ?

[Roy Morgan]

At 11:15 AM 4/25/2005, you wrote:
>As I recall from old posts -- it was for an optional squelch.

Barry,

That is correct.

The function switch has the needed extra position and the wireing harness 
has the needed wires to install the squelch.

There have been reports of R-390A's with the squelch installed (though I 
don't have one). It could be done by a field change involving a relay, the 
tube socket and tube and a few components.  If I remember correctly, it 
used the existing relay in the audio deck that grounds the audio signal, in 
addition to the added relay and a new marking plate for the Function 
switch. I would suspect that the added relay was a 10 milliampere type 
arranged in the plate circuit of a 12AU7/5814.  See the R-390/URR schematic 
for the details.

Roy

- Roy Morgan, K1LKY since 1959 - Keep 'em Glowing!
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