Garey and Dennis, thanks agian for the inputs. Regarding tubes, I have replaced those afected by AVC/1 and AVC/2. Nothing changed. Maybe I will need to try to redo this based on what Garey wrote. I will get special attention to the 6BA6 which is driven by AVC/1.
These are some effects that I would like to line up and make sure you have the details - After 10-15 minutes Smeter goes to S1. If I turn the radio off and on it will do again, but journey is shorter. The S-meter will come from S4 to S1 in 5-6 minutes. - During the journey to S1, after start up, if I am in Fast AVC and switch to Slow (introducing the 1uf capacitor), the S meter's needle deeps to the left and gets up again. I hear the RX background noise to pulse too. It does that once. - In any circusntance there is a slight S meter difference when I switch from SAVC to FastAVC and vice-versa. In SAVC it reads about half S unit more (to the right). - I have realized that when th BFO is on, the S-Meter moves a bit do the left. Normally I would answer to someone that would have posted something similar to it that the AVC discharge path is malfunctioning. I have checked the resistors in this path. I have also checked the time constant capacitor in the AV/2 and AV/1 circuits. I will have time to check spurios oscillation and/or grid leak whan I get back home. I will be away until year's eve or so. Please send any ideas that are very much welcome. Best regards Fred On Fri, 26 Dec 2008 04:19:24 -0200, Garey Barrell <k4...@mindspring.com> wrote: > Fred - > > I have been traveling and missed some of this thread. Try subbing tubes > in the AVC stages. Often an IF tube will be gassy, and the grid will > "lose control" after 5-20 minutes of warmup. The 12BA6 is particularly > susceptible to this problem, even in "New Old Stock" tubes. You > sometimes have to try three or four before finding a "good" one. The > AVC circuit is so hi-z that it takes very little grid current to upset it. > > 73, Garey - K4OAH > Glen Allen, VA > > Drake 2-B, 4-B, C-Line & TR-4/C Service Supplement CDs > <www.k4oah.com> > > > > py...@integral.com.br wrote: >> >> Dennis, merry xmas to you and yours, firts of all. >> >> >> >> Thanks for the input. I don not know if I my explanation was clear >> enough. The long S-meter journey to S1 just occurs after power the >> unit up and for 10 or so minutes. After that the behaivor is normal. >> Yes my first shot was a opened path to discharge the AVC circuitry. >> Unfortunately I have not found anything to blame. Did you consider >> that after the initial pb the behaivor seems to be normal ? Regards Fred >> > > _______________________________________________ > Drakelist mailing list > Drakelist@zerobeat.net > http://mailman.zerobeat.net/mailman/listinfo/drakelist _______________________________________________ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
