Quote:
Originally Posted by Boater Sam
I have seen power valves and rectifiers that have become plastic due to excessive heat and distorted that way.
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Yes I have seen that too.
In general though I agree that calling glass a super cooled liquid or thinking of it that way is wrong. Probably best called an amorphous solid.
So the question remains, if you have an 80 year or more old globe tube, but not a power tube that been heated, where the electrode structure has no upper mica support to the bulb, and it is badly bent over and the filament and grid are shorted or near shorted...how did it get that way?
If we propose it was manufactured that way, is that likely ?
One thing I have noticed about components from this era, there appears to have been a lot of pride in the appearance of them and the QC was reasonable. Everything was well done, right down to elaborate and colorful packaging. I don't think a customer would have accepted and paid for a valve in this obviously unusual condition. If it was seen at the factory it would have likely failed testing and been discarded. So I struggle to think this is likely.
(I'll attach a photo of one tonight).
So if the tube was "normal" when new, did it really slowly change over 80 years ? and if it did, was it gravitational force that caused it and if it was, did the glass support system move or not ?
One thing about the way the glass supports were done, they are actually very thin (a small fraction of typical window glass thickness) near the point where the support assembly joins the bulb. A very small change here would result in a larger position change much further away near the top of the anode assembly. But one thing here, it appears also that the relative positions of the wires crimped into the support assembly, which set the inter-electrode spacings, have moved (or were incorrectly placed initially) as well as the overall position of the support moving.
So I'm not really 100% convinced either way.