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
>>
> 
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