[Milsurplus] 1625 expert needed

[sbjohnston at aol.com]

Light from what should be the vacuum space in a tube seems like it would have to be caused by gas.  Maybe something else is going on, but I do not know what it would be.
Gassy tubes usually do not perform well, but I suspect that can vary with the application and it may not make much difference in some circuits.
A related observation:
I have seen 807s and 1625s that show purple glow on the glass in a pattern that matches the inner structure of the tube.  In other words, when the tube was under power, stray electrons must have been spraying out of the cracks and crevices around the plate and when they hit the glass it caused a purple glow in the outline of the gaps in the structure.  I believe this is called fluorescence - a very cool effect.  
The first time I saw this I assumed it was a gassy tube, but upon closer inspection I could see it was only the glass itself that was lighting up - there was no glow at all in the vacuum space inside the tube or around the mount or metal elements inside.

Steve WD8DAS   

sbjohnston at aol.com   
http://www.wd8das.net/   http://af4k-crystals.com/   
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