[Milsurplus] Tube storage?

[gl4d21a at juno.com]

I threw the idea out to start this kind of discussion.  I suspected that either dry nitrogen storage, or reduced pressure storage might extend the shelf life.  Sounds like it might be something worth considering for the ceramic tubes.  Or maybe storage in some really heavy molecular weight gas (Freon?).  In any event, the storage container would not have to be at hard vacuum like the inside of the tube, just much lower than atmospheric pressure to reduce the diffusion rate through the glass.  I have no idea of the quantitative values, if the inside is at hard vacuum and the outside at 15 psia, would reducing that to 7.5 psia reduce the diffusion by half and double storage life?  I guess the calculations would have to be done for the partial pressure of the suspect gasses, but intuitively, even a rough vacuum outside should help.

I have heard that the acorn tubes had the poorest seals of that era.  Yet, my Measurements Grid Dipper still has 194x date coded acorn tube in it, and it is still good (or was last time I fired it up).

73,
George
W5VPQ


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