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In Reply to: RE: These here tubes can be tricky little buggers! posted by vinnie2 on September 28, 2016 at 03:26:25
"why would the tube drawing more current cause a hum?"
You said anode voltage was much higher than the other tube. That would indicate it was drawing less current. A number of things could cause that, including misalignment of the grid (as someone else mentioned) or a defect in the filament. If the filament is AC heated, all bets are off. :)
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Buy Chinese. Bury freedom.
Follow Ups:
All bets are off then. Forgot to mention that all though the 845 has dc on the filaments, I left the 26's ac.
Any ideas what might cause it with ac heated filaments?
Edits: 09/28/16
It's difficult to guess, almost anything that unbalances the filament-grid relationship could do it. Did you happen to check it for shorts in a tester? Could still be bad if that shows OK, but not likely vice-versa.
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Buy Chinese. Bury freedom.
NO, I just tossed it once I saw that it was causing the hum problem. It was a used pull from a hamfest, so the odds are there was something wrong with it.
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