[AMPS] heating tubes....

Tom Rauch W8JI@contesting.com
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-
500Z. 

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
w8ji@contesting.com

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