tubes getting gassy over long term storage

Since there is an issue of 3-500 and other type tubes getting gassy over long term storage. Why did they not put them in sealed cans with the same gas that was in the tubes. I am sure the cans would over time have oxygen invade them like the tube. but I think that would gave the tube a much longer tube life. Maybe adding at least 20 to 30 years.

 

There is not supposed to be any "gas" in a tube. Just a vacuum (absence of any gas) or as close to it. Over time air from the ambient atmosphere leaks past the seal between the pins and the glass. Possibly out gassing of the tubes internals may account for this also. Maybee possible to store tubes in a vacuum chamber that you could periodically pump down to keep them good!??

 

KM1H s'plained the problem w/ some Eimac 3-500Zs here (link):

"Eimacs 86-89 had bad seals and welds all due to QC problems at the new SLC plant; the welds were due to trying to save money by using only 3 spot welds.
I dont have the actual date code groups handy."​

IIRC, there was also concern that early Chinese-made 3-500Zs weren't pumped down as far, and wouldn't hi-pot as high as early US-made 3-500Zs. The pair that came to me in 1975 (in my Heath SB-220) lasted 'til cockpit error caused a failure, about 30 years later. The next (new) pair from China lasted only 6 years before one arced.

 

Tubes should be vacuum packed.

 

I think he was pulling thyne leg.

TOM K8ERV Montrose Colo

 

Problem with the Chinese tubes is I'm hungry again an hour later.

 

BTW, the date code looks like this:

(click for bigly image)

 

When I was a kid Got a chance to pop several tubes "old TV's in a barn". So what was the smell? I thought it was a argon gas or something.

 

Probably the gettering material that was fired to remove excess gas during manufacture.

 

And gassy.