Jul - The R-390A Frequently Asked Questions Page

caps", but so far has not done the operation. With all the experiance out there, i am shure somebody has
had similar=20 encounters. By the way thank you guys for all the first class info, my printer is running
red hot. Regards Ivan Heimdal
From djmerz@3-cities.com Wed Jul 17 19:31:21 2002
Subject: [R-390] AGC problems
Ivan, I'm sure you'll get plenty of advice on this - I'm a relatively new guy to R-390a and the solution to
this problem for me for ssb reception was: put in the two diodes that improves the agc response for ssb -
discussed plenty in the R-390a archives improve the audio amp - first I used an external audio amp on
the diode load connection out the back - this was excellent. second I built a modified internal audio amp
using 6360 tubes ala Electric Radio article - this wasn't quite as good as the external amp but still very
good and is what I use because I don't need any external equipment. Dan.
From twleiper@juno.com Wed Jul 17 20:09:07 2002
Subject: [R-390] R-390A Y2K-R2 - in ONE BIG FILE!
writes: ... > snicker, > snicker. One of the few perks for working at a university.
"working at a university" Is that not a contradiction in terms? snicker snicker
By the way, my GoogleBit connection finished the download before the sound of my mouse click even
reached my ears. Twit Hammarlund
From w9wis@charter.net Wed Jul 17 20:19:33 2002
Subject: [R-390] AGC problems
Your problem sounds very much like the one that plagued my R-390A. The cause of my problem was
eventually found to be an intermitant short in the 4 Kc filter.
My 390A would start out with good audio and agc but when it warmed up the audio would distort until
I turned down the rf gain... obviously no agc action was present. I also found the agc voltage to swing
way low when this occurred. Sometimes after some minutes audio would improve and agc would
return to normal. It was discovered that when the filter heated up as the radio was on it's internal
components would expand/contract and short to the case of the filter grounding the agc voltage.
Since all the filteres are, I believe in this circuit, it could be any filter that is bad. The usual suspect
seems to be the 4 Kc filter as I'm told it was generally the most fatigued due to use. Mike, W9WIS
From twleiper@juno.com Wed Jul 17 20:20:03 2002
Subject: [R-390] AGC problems
writes: > Can somebody tell me what the problem could be on my R-390-A, that i > just > bought.
Strong stations completely overrides my AGC, i have to back > off on > the RF-Gain to get a
reasonably readable signal. I figure there must > be a fault > somewhere.
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