>>So then if all of the tube isn't evacuated, none of it is evacuated.
>>
>The evacuated space acts as one entity. The space is pretty well
>evacuated and sealed at manufacture. If a glass to metal seal has a
>microscopic imperfection, the vacuum fades as air invades.
>
Right. In other words, the entire tube inside the glass is "evacuated"
space. So the glow from the beams striking the glass envelope is in the
evacuated space. Other people have pointed out that if the tube is gassy
I would see the blue glow *inside* the anode assembly. In other words
look in between the holes in the plates and see if the blue glow is in
there. This explanation made the most sense to me.
So there is no difference between one area inside the tube and another in
terms of the vacuum. Either it's all gassy or it's got a good vacuum.
Perhaps we are saying the same thing and I am misunderstanding what you
were saying...
>>But you said that one blue glow is from electron beams striking the
>>envelope. The other is in the "evacuated space." How do I know which
>>from which?
>>
>By observation.
Well, since the glow from electrons hitting the envelope does occur
inside the evacuated space, it's kind of confusing by your definition. I
think what you are trying to say is that if the blue glow happens at the
surface of the glass envelope, then it's not a problem. If the blue glow
happens in the middle of the free space inside the tube, then it's gas.
73,
Jon
KE9NA
--------------------------------------------------------------------------
Jon Ogden
jono@webspun.com
www.qsl.net/ke9na
"A life lived in fear is a life half lived."
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