[AMRadio] Muting the R390 on transmit

Jerry K w5kp at hughes.net
Wed Dec 2 08:33:20 EST 2009

Greetings, John... 
I noted you said you didn't have a manual or schematic for this 
receiver. Before you do anything else, do yourself a giant favor and go 
to these two websites:

R-390A FAQ Page <http://www.r-390a.net/faq-refs.htm>
An exhaustive list of carefully gleaned technical references on this 
fine receiver, in downloadable PDF format.

R-390A Y2K Manual (Release 3) <http://www.r-390a.net/Y2K-R3/index.htm>
A complete annotated and updated version of the R-390A Technical Manual. 
This manual has been painstakingly compiled, rewritten for clarity and 
accuracy, and is kept updated by a large group of experienced techs who 
own and have worked on the R-390A for many years. Downloadable (PDF 
files) by chapter, or as one massive file.

Just about anything you need to know is available on these two web 
pages. I have only rebuilt five of these great receivers over the years, 
and I have a complete set of the original military versions of the 
R-390A manuals, but like most of us R-390A nuts the "Y2K" manual is my 
working bible for this receiver. It is much easier and faster to use 
than the original military versions. You will benefit (at no charge, no 
less!) from the hundreds of hours invested in updates, corrections, and 
clear, easy to follow troubleshooting information contained in the 
latest release of the Y2K Manual. These guys have invented the wheel for 
you, don't waste time reinventing it. :)

Have fun, Jerry W5KP

John King wrote:
> Thanks for the reply, Grant. My R 390 doesn't mute when terminal 9 is grounded. I have connected an alligator clip lead to terminal 9 and then connected the other end of the clip lead to terminal 16 which is ground and there is no effect. I can't figure out why there is no effect when terminal 9 is grounded. What do you think, Grant? I do not have a manual or schematic for the R390. 73, John, K5PGW

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