>
>On Tue, 17 Oct 2000 16:57:11 -0400, Tom Rauch wrote:
>
>>Eimac and other large power grid tube manufacturers use gettering
>>materials activated by filament heat or anode heat.
>>
>>Without that, the tubes eventually gas up and fail.
>______________________________________________________________
>
>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?
>
I have never seen a tube with a leaky seal Get better with use. I have
never seen a tube with good seals gas up in storage. Tom's gettering
tales were the result of trying to explain the fact that tubes which had
sustained a big-bang very rarely showed gas. There was:
1. no sign of gas when tested on a high-pot.
2. a greatly increased value of R-supp. with no sign of having been too
hot.
Mr. Rauch claimed that the 3-500Z was re-rated from 400mA to over 500mA
by Eimac and that he posesses an authorization letter to that effect, He
has never published such a letter.
end
end
- Rich..., 805.386.3734, www.vcnet.com/measures.
end
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