Re: {Collins} Eimac 3-500Z tube value?

["Jim Monk" <jmonk1@xxxxxxxxxxxx>]

Concerning the problem of Oxygen Migration in PA tubes such as the 3-500Z as 
being currently discussed on this list....... has anyone had experience in
"re-establishing the getter" by energizing the filaments over an extended 
period of time and then later "ramping up" the HV to the plate utilizing a 
variac or similar device.

This procedure is reported to help avoid the "flashover" which can occur 
when the tube has "been on the shelf" for long periods of time and then 
energized with the normal HV, causing tube failure.

It is my understanding the initial vacuum as established in manufacture is 
frequently lost when the tube has been stored and unused for long periods.

I have two Military 3-500Z tubes still sealed in the original boxes and 
plastic packaging and would appreciate any thoughts on the effectiveness of 
the above procedure to avoid failure of the tubes, if and when I need to 
install one of them.

Comments would be welcome.

73/jim/W0JJL