[R-390] R390A AGC Troubleshooting technique.

[Bill Riches]

Check R546 - 180k off pin 1 of V509 and R 506 - 220k of pin 2 of V506.  I
have had them change value higher and kill agc operation

73,

Bill, WA2DVU
Cape May, NJ

-----Original Message-----
From: R-390 [mailto:r-390-bounces at mailman.qth.net] On Behalf Of Alan Victor
Sent: Thursday, October 02, 2014 8:01 PM
To: r-390 at mailman.qth.net
Subject: [R-390] R390A AGC Troubleshooting technique.

Currently in the process of troubleshooting the AGC in the R390A. The
sensitivity on all bands is about 5 uV some bands better than 1 uV. The unit
needs alignment. However, the AGC is clearly absent. The largest negative
AGC voltage seen is about -5 V at 3-4 terminal. I will be looking at all the
known documented causes from mechanical filters to leaky caps, open xmfr's,
bad tubes and so on.


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