For sufficiently small values of HVAC, several R390s have had HVAC installed!
Dave Wise > On Mar 12, 2024, at 11:11 AM, Barry <[email protected]> wrote: > > 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
