[Amps] 3-500Z grid short question

Steve g8gsq at f2s.com
Tue Feb 9 08:14:38 PST 2010


I'm looking at a TL922 for a friend. One tube has a grid - filament 
short, the same tube has an overheated filament pin. The solder has 
obviously reflowed at some point but hasn't totally run out of the pin.

Might there be a link between the two? I can't think of anything  obvious.

Friend didn't notice anything specific happen - he tuned up normally on 
20m, then next time he came to transmit there was no rf out and 
continuous standing current. He's had the amp for many years and uses it 
occasionally rather than continuously. Years ago one of the original 
Eimac tubes went with a bang and took out one grid choke. After repair, 
Chinese tubes went in. This time there's no sign of any damaged 
components and the grid chokes are intact.

I know this amp and this problem has occupied a lot of space here (I've 
been a subscriber long enough to have seen plenty of it). Please, let's 
not reignite any old wars.

Steve  G8GSQ


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