[AMPS] parasitics

[Peter Chadwick]

Been out a couple of days.

Spectrum analysers - can lie worse than a Personnel manager, even more so
with a FET probe.

Thoriated filaments. Rich is quite right about the carburization business -
it's described in old editions of Terman. However, leading on from that, the
maximum emission when saturated from a 3-500Z filament (or any of the 5volt,
14.5Amp thoriated filaments is of the order of 60 to 70mA/watt.  That means
a maximum tube current, in saturation, as opposed to arc current, of around
4 to 5 amps dc. If that is going to bend filaments, why is there no warning
about running the filaments on dc? And will the grid bend at 5 amps? Maybe
someone can calculate the bending force. If that current is the result of a
parasitic, where does the plate get its current from?

This is why I have a problem with the parasitic theory.

73

Peter G3RZP

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