[AMPS] heating tubes....
Wed, 6 Sep 2000 19:26:22 -0400
> >€ I have tested many metal anode-cooler 3-500Z tubes that g/fil. shorted
> > after a big-bang. The majority had under 3uA of grid/anode leakage at
> >8000v. The subsequent autopsies revealed no arc marks on the grid.
> The reasons for observing low gas currents if you delay more than a few
> seconds after the event have been explained many times - "it's the
> gettering action".
Not only that Ian, 8000 volts is FAR too low for breakdown in a 3-
Normal peak voltages almost reach that amount, and any over-
driven or under-loaded operating conditions, even if a transient
condition, will cause that tube to fail.
A good 3-500Z will not break down at 11 kV. A bad one will often
stand-off 8000 volts or more.
73, Tom W8JI
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