[Milsurplus] [Boatanchors] Smart People: Gassy Tubes Reversable?

[C.Whitaker]

de WB2CPN
My experience with gas inside vacuum tubes is that it leached
out of the metal in the tube.  Used to be that the manufacturer
expected some gas to be produced during and after the tube
was made.  So, a small thing called a Getter is placed into the
tube.  It absorbes any gas found there.
Large transmitter tubes often show a light blue glow when
under high voltage pressure.  Of course, mercury vapor tubes
are supposed to do that.  The better tube checkers will indicate
if the tube shows any gas.
Your idea will work if the vacuum chamber is good enough.
It should replace any floating gas molecules with nothing.
NOTHING:  "A footless sock with no leg."
73  Clete
++++++++++++++++++++++++++++++++++++++++++++++++




On 12/3/2013 3:07 AM, hwhall at compuserve.com wrote:
> Theoretically....but it wouldn't all come out, and it may take a very long time to get out. Seems to me that it would work better when there is a lot of gas. The less gas, the longer it will take for gas molecules to 'find' the leak that let them in and then wander out. In a near-vacuum, there's a lot of empty space between gas molecules, they won't effectively drive molecules out of the leak because the molecules bump into each other so seldom.? I imagine it would be more practical to set up a glassworking shop to open the tubes, install new getters, pump them down and fire the getters. When one has that technology, one might also even investigate a way to treat or repace spent cathodes.
>       
>
>   Wayne
> WB4OGM
>
> -----Original Message-----
> From: David Stinson <arc5 at ix.netcom.com>
> To: milsurplus <milsurplus at mailman.qth.net>; boatanchors <boatanchors at mailman.qth.net>
> Sent: Mon, Dec 2, 2013 10:42 pm
> Subject: [Boatanchors] Smart People:  Gassy Tubes Reversable?
>
>   
>   
>   
> 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?
>   
>   
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