[Amps] GS-35B Tubes Glow In The Dark

[Tony King - W4ZT]

Friends,

Recently I have worked on a friend's GS-35B two tube amp.  I replaced 
both tubes in it.  During the testing after the tube swap I noticed that 
by looking straight down through the anode cooler I could see a distinct 
glow. Interestingly enough, one tube was glowing BLUE and the other tube 
was glowing GREEN!

I recently completed building a tube tester to test the GS-35B 
<http://tester.gs35b.com> and had used it to determine the condition of 
the tubes we replaced in the amp above.  Today I tested four more new 
tubes specifically looking for that glow.  I replaced the opaque chimney 
with a Coleman lantern globe temporarily for these tests so I could see 
the ceramic. The pictures I have posted on this page are the results: 
<http://glow.gs35b.com>

I'd be interested in any pictures that any of you have taken or do take 
of your tubes glowing like these; and, with your permission, to post 
them on the page with the others.

We have already had some interesting discussions about how this glow is 
created and the best explanation we have come up with so far is electron 
bombardment of the ceramic causing trace elements to fluoresce.  If any 
of you have a better explanation (NOT that the tubes are gassy... 
they're not) I would love to hear about it.

73, Tony W4ZT
http://gs35b.com