> You have me curious about something. I recently fired up my old Heath
> SB-1000 after it sat idle for about six years. It was fine when put in
> storage, but when powered up, the 3-500Z lit up like one of those Radio
> Shack globes with the "lightning" effect. I replaced it and all was well.
>
> My question is, has this tube gone permanently bad or could it be
> revived with carefully controlled "gettering"? I have a suspicion if
> there is that much gas in there, it's gone for good. Any one have
> experience of this sort?
If you can heat the anode by running the tube at low anode voltage
and forward grid bias, and let it cook, sometimes they will getter
out the gas.
I've been successful quite a few times doing that with old 3-500Z's
that weren't too badly gassed.
Another way to getter the tube is through a current limited arc.
Sometimes that's done with new tubes. I haven't tried that myself.
73, Tom W8JI
w8ji@contesting.com
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