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Antique Radio Technical Forum
Silvertone 6136 AVC & Cathode Bias

Posted by Thomas Dermody on 09/20/2005 22:52

Have you checked your AVC resistors as well as the 1 meg resistor in the socket of the eye tube? If the socket resistor drifts high, the eye will tend to stay open. If the AVC resistors drift high, the eye may simply not function well. If you haven't replaced the AVC condensers (you say you replaced all paper condensers), leakage in these will cause the eye to stay open.

My Crosley 1117 had this lack of sensitivity in the eye even with all components replaced. I slightly redesigned the eye circuit. You can see the oddness of the original circuit and can note how its being linked to the radio's negative bias would tend to not allow the circuit to fluctuate on its own. I did not change this at all, but did a different modification. However, modifying the radio to a standard AVC circuit (found in most radios with the 2.2 meg resistor, etc.) would also solve the problem. The circuit which my radio posesses, though, actually boosts quiet stations and mutes loud ones, which is why I left it somewhat original.

Thomas



Silvertone 6136 AVC & Cathode Bias 
Mack Stanley 09/20/2005 00:19 
rghines1 09/20/2005 13:44 
Norm Leal 09/20/2005 18:23 
Thomas Dermody 09/20/2005 22:52 
Mack Stanley 09/23/2005 14:06 
Thomas Dermody 09/23/2005 22:44 
Mack Stanley 09/25/2005 18:35 
Thomas Dermody 09/27/2005 21:01 

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