>
>Ian,
>
>>There are two ways gas can get into a vacuum tube. One is through a faulty
>seal, as Rich said. But even if a tube has perfect seals, the inside
>surfaces of the tube can very slowly release gas.
>
>Ok, that makes sense. I suppose an inverted way of looking at it
>is that if the tube -didn't- emit any gas internally, there would
>be no need for a getter.
>
>One of the reasons I asked was based on experience. After pulling
>a new 3CX400 from storage, (probably 5 years or so) it immediately
>glitched when B+ was applied. ...
This is yet another reason to have a hi-pot tester. I used to test
''tetrodes with handles'' in the Plywood Box amplifier. If a tube showed
substiantial gas on the hi-pot, plugging it into the amplifier was out of
the question.
- R. L. Measures, 805.386.3734,AG6K, www.vcnet.com/measures.
end
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