[Boatanchors] Smart People: Gassy Tubes Reversable?

[Jim Wilhite]

I don't think it would be practical Dave and would take a very long time. 
If the tube is leaking, which all do to some very minor extent,  air is 
entering which is a greater threat than the gas already in the envelope, the 
filament cannot survive in the presence of air.

You won't have just the "gas" migrating into the envelope.  Somewhere around 
here I have a document explaining how to reinvigorate tubes that have been 
stored for an extended time.  I also have a document somewhere explaining 
about the amount of gas present, which is minimal unless the manufacturing 
process was faulty.

What are the symptoms you are seeing in those tubes?

Jim
W5JO

----- Original Message ----- 

> Some otherwise valuable tubes have taken-in variable
> amounts of gas over the decades.   NOS transmitting tubes like the 211 are 
> often gassy out of the box and cannot be readily "de-gassed" like some 
> large Eimacs.  Even some NOS 1625 and 807 are starting to show signs of 
> gas.
>
> Question:  If a batch of such tubes were put into a large
> vacuum chamber, pumped-down hard and left there for an extended time- even 
> a year or more- would the gas
> in those tubes migrate back out?