Well, the R390 could certainly use an HVAC system... :-) Barry - N4BUQ
----- Original Message ----- > From: "David Wise" <[email protected]> > To: "Cecil acuff" <[email protected]> > Cc: "R-390 Mailing List" <[email protected]> > Sent: Tuesday, March 12, 2024 1:09:34 PM > Subject: Re: [R-390] AGC Troubleshooting > Oops AGC. It said that at first, and then auto corrupt changed it to HVAC. > Good > times. > > Dave Wise > >> On Mar 12, 2024, at 9:56 AM, Cecil acuff <[email protected]> wrote: >> >> It’s been my standard practice to replace all paper caps in the “A” model >> radio. >> You may be able to find the single culprit but next week, or month there >> will >> be another. I would just bite the. Bullet and replace them all! >> >> Cecil >> >> Sent from my iPhone >> >>> On Mar 11, 2024, at 5:44 PM, [email protected] wrote: >>> >>> I followed Charles Steinmetz's troubleshooting procedure for AGC issues and >>> the following resulted after tuning to a very strong BCB station: >>> >>> >>> >>> Voltage Terminal 3 & 4: -0.37V - not good >>> >>> >>> >>> Then step 2: >>> >>> >>> >>> Resistance Terminal 3: 460k - maybe passable >>> >>> Resistance Terminal 4: 24.6k - horribly off spec >>> >>> >>> >>> So, my problem is most likely in "any of the several dozen bypass caps on >>> the AGC line in the IF and RF sections, or leakage to ground in one or more >>> of the mechanical filters". >>> >>> >>> >>> Now my ignorance shows up. How do I identify what are bypass capacitors? I >>> assume that these are capacitors that go to ground? >>> >>> >>> >>> I also note that, on the very strong BCB station, I get no sound output >>> until the RF gain is up to 8, if that helps narrow down where I should start >>> searching. >>> >>> >>> >>> Thanks in advance for any help. >>> >>> >>> >>> Regards, >>> >>> >>> >>> ______________________________________________________________ >>> R-390 mailing list >>> Home: http://mailman.qth.net/mailman/listinfo/r-390 >>> Help: http://mailman.qth.net/mmfaq.htm >>> Post: mailto:[email protected] >>> >>> This list hosted by: http://www.qsl.net >>> Please help support this email list: http://www.qsl.net/donate.html >> ______________________________________________________________ >> R-390 mailing list >> Home: http://mailman.qth.net/mailman/listinfo/r-390 >> Help: http://mailman.qth.net/mmfaq.htm >> Post: mailto:[email protected] >> >> This list hosted by: http://www.qsl.net >> Please help support this email list: http://www.qsl.net/donate.html > ______________________________________________________________ > R-390 mailing list > Home: http://mailman.qth.net/mailman/listinfo/r-390 > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[email protected] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html ______________________________________________________________ R-390 mailing list Home: http://mailman.qth.net/mailman/listinfo/r-390 Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
