[Paul Philco322]

Well I have been listening to tube sets a long time, occasionally have had sound fade on a set as a tube fades. Today I am off work and was listening to a local and I heard a pop and then nothing on my RCA.

So being lazy I turned it around and felt the tube for heat, 12SA7 cooler than rest but pilot light was on and had a hum in set.
I had a spare 12SA7 and yes that was the culprit, have you just had a tube go poof? I was of the impression that they may go weak and then just the set fades, should I be concerned my radio has a voltage problem or just resign myself to the fact that a 70 year old tube cant just cut it any longer? Amazing they last so long I guess. Who knows how long the one that popped was in service, from the graphics on tube I would say it was from late forties.

Paul

[David]

Had the same thing happen years ago so replaced the tube the new one lasted about 30 seconds and it went pop. So starting checking all caps and resistors connected to the tube socket found a bad cap. The set had been recapped about 6 years before.

[Paul Philco322]

Yeah this one was done several years ago, I played it for another hour or so after the swap, so hoping just tube, will see I guess, sometimes you just get old like the tube, who knows how many hours it had on it. Paul

[RodB]

Paul, your 12SA7 has two sections and one is for the oscillator. When the oscillator quits you may hear some static or hum but no stations. It seems that is what happened to yours.

[Paul Philco322]

Thanks RodB, common enough tube and I have some similar 6 tube sets so I pick some up now and then to have on hand, easy fix and I like those kind of fixes. Paul