[Amps] GS35B glowing ceramic TSPA

[John T. M. Lyles]

Thats fascinating work, Tony. Impressive tube tester also!

Your electron bombardment theory seems very plausable for that tube. 
It would be interesting to see innards of one, to try and understand 
this more. Maybe there is a space in the arrangement of the 
electrodes in there, which is allowing electron beaming to hit the 
ceramic. I would be curious if it is adding any heat load to that 
ceramic. That would require measuring the different tubes which some 
sort of non-conductive temperature sensor.

Did you have any sign of parasitic oscillation in your tester when 
you get up to 0.4 Amp Ip?
Was that one tube with the higher bias requirment a new tube or an old beater?

With 2.7 kV DC Ep, Xray production should be virtually nil.

73
John
K5PRO

>Message: 6
>Date: Fri, 24 Feb 2006 00:58:32 -0500
>From: Tony King - W4ZT <amps080605 at w4zt.com>
>Subject: [Amps] GS-35B Tubes Glow In The Dark
>To: amps at contesting.com
>Message-ID: <43FEA088.8040508 at w4zt.com>
>Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
>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