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Re: red 8 mm tubes :possible failure
re: 8mm red tubes
I had some tubes of 10mm showing the same effect. Possible jelly-beaning
when connected to the electronic transfo first.
The tube does not run too hot first, but slightly hotter than normal.
It takes several minutes to one hour before getting fully red again.
In my experience in making very small tubes, (down to 4mm) this is an effect
of improper glas heating during bombarding.
the smaller the tube, the worser the relationship volume/surface in the tube,
so you have much more surface per gas volume.
Surface emits impurities when not proper bombarded.
Start clear red tubes bombarding at a pressure as high as possible
(12 - 15mm dependent on length ans your bombarder)
Set bombarder to a very low current.
Start until your "thermometer paper" chars to dark brown color.
Decrease pressure and increase current.
When electrodes are hot, the paper should start burning (glowing).
.... But watch out when the glass gets soft!!!!
pump down and repeat this procedure at least 2 or 3 times.
Starting with such high pressure is only applicable to clear glass,
because the yound you hear when starting bombing stems from shock waves
inside the tube which will blow off any phosphor immediately.
Would be interested in your results.
Marcus Thielen
Student of physics at Duisburg University, Germany.
marcus@ttphysik.uni-duisburg.de
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