[Kenwood] TS-820 ALC more yet

[Steve]

At 06:40 PM 3/11/2012, Kenneth G. Gordon wrote:
>According to my calculations, it will take 26 minutes for the ALC to 
>leak off to zero with no
>audio input as it now is.
>
>Sounds like an open resistor to me...

In the glorious good ole ancient days of Heathkit, The 
SB100-SB101-SB102 series transceivers suffered a very similar 
symptom, except it affected AGC. After transmitting, when the radio 
went back to receive, the S-meter would peg and the sensitivity 
wouldn't come back until the capacitor that was charged by the leaky 
diode had discharged, just as if the RF gain was turned all the way 
down; usually took up to 15 seconds to fully recover. IIRC, it was 
usually a diode in the ALC circuit that had become leaky, I believe 
associated with the final's' screen grid power source. IIRC, the 
condition of the final tubes seemed to contribute, in that new, 
non-leaky tubes would appear to alleviate the problem. But pretty 
soon, the new tubes would "wear in", causing the problem to re-occur 
and gradually become worse.

Steve, K0XP 



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