[Amps] "Tubes 201" - How Vacuum Tubes Really Work

[Peter Chadwick]

Rich said:
>I autopsy tubes, and I have no yet seen an arc mark in a kaput tube  
with a good vacuum.<
It's sad that G6JP is no longer alive. He spent his entire working life doing tube manufacture and applications at the M-O valve company, and he said that flashovers weren't uncommon. There's also the articles in the Journal of the IEE. My father in law tells me that they had flashovers in continously pumped tubes at the QRO point to point stations he worked at -although the biggest problem was when someone with greasy fingers touched the grid during re-assembly. That meant that they had a lot of pumping to do before the valve really got hard.
So Mr. Measures, the fact you've never seen what you take to be marks of a flashover in a  tube with good vacuum doesn't mean that it doesn't occur. But, of course, proving (or disproving) a negative is not easy, so either party can sit back in the warm glow of satisfaction that really, they're the ones who are right!
73
Peter G3RZP