[Milsurplus] loooooong-term tube storage ...

[J. Forster]

Eric Jones wrote:

> de N4TGC Eric
>
> Storing tubes in an inert medium is easier than it sounds - but I'll start with
> a harder method, since that was proposed: a good air conditioning vacuum pump
> can achieve 29+ACI- of Hg, and it can be made from nothing more than a surplus
> refrigerator compressor  [snip]

If you are not trying to get the container down to high vacuum, the pumping task is much
easier, but the container problem is not. One atmosphere can put a lot of force onto a
container's walls, and if it buckles, any effort to preserve the tubes will likely be moot
very quickly. Also, getting a good reclosable seal is non trivial. Somehow, welding my tubes
into a tank and then having to cut it open to get one out seems a bit excessive.

If you do want to back fill the container with a gas such as N2 or CO2, it seems possible.
I've seen some military shipping containers that are steel drums with O ring seals and a
clamp band. If one were to take one of those and fit it with a valve or two, it could make a
suitable container.

For nitrogen, one would pump it down some, fill with N2, then pump again and repeat the
process several times. How far you pump it down would depend on the strength of the
container. You'll never get all the air out this way, but it might be enough.

With CO2, you could use the gas density to help. Again, it'll not completely eliminate the
air.

After sealing, the container will have to be stored in a temperature stable place or it may
leak as the pressure increases or decreases with the temperature.

All in all, I doubt it's worth the effort.

*****

Something just occurred to me....  : At flea markets, I've seen small ceramic transmitting
tubes stored in coffee can sized  mil shipping containers like I described above. Does
anyone know if they were filled with something OTHER THAN AIR ??

-John