[Milsurplus] Tube storage?

[Scott Johnson]

As a practitioner of hi and ultra high vacuum techniques, my position is 
that this would be impractical from an economic standpoint. A good vacuum 
sytem capable of maintaining a 10-7 torr pressure is still very expensive, 
and even more expensive to operate.  Glass tubes , properly manufactured, 
and with reasonable care in storage should last 100+ years, if it were 
neccesary, it would probably be easier to re-pump them at some later time. 
I have not noted a "shelf life problem in any NOS tubes, with the exception 
of ceramic-metal types(which have a much higher diffusion rate).  They 
should be rotated into service periodically to clean them up. Ceramic metal 
and some Eimac glass types have tantalum and titanium components , which 
exhibit good gettering action at elevated temperatures(as in operation).
regards,
Scott
----- Original Message ----- 
From: "Peter Gottlieb" <nerd at verizon.net>
To: <gl4d21a at juno.com>
Cc: <kargo_cult at msn.com>; <milsurplus at mailman.qth.net>
Sent: Thursday, March 16, 2006 10:44 PM
Subject: Re: [Milsurplus] Tube storage?


> Before becomming concerned I would like to see a real analysis done to see 
> if this is an issue or not.
>
>
>
> gl4d21a at juno.com wrote:
>> Hue sent:
>> Another thing i think about is, these tubes ain't being made any more, 
>> and your
>> precious tubes will eventually crap out, even the new ones, because the 
>> glass is
>> not 100% impermeable. Possibly we will pass from the scene before all the 
>> tubes
>> will, but be assured, tubes will one day be only "look at" items for 
>> collectors. The
>> only exceptions i can see is some tubes still kept in manufacture for the 
>> tube
>> audio cultists, tubes such as 6L6 and a few others.
>>
>> Group:
>>
>> Has anyone considered storing their tubes in a high vacuum?  Hard vacuum 
>> is a lot easier to come by these days than it was historically, so that 
>> would be one way to preclude migration through the envelope.  Or is 
>> internal out gassing the real problem?
>>
>> 73,
>> George
>> W5VPQ
>>
>>
>>
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