[Amps] A request from Portugal (Was: RE: testing 572 B tubes)

[Bill Turner]

ORIGINAL MESSAGE:

At 01:04 PM 3/4/2006, Ian White GM3SEK wrote:
>There are some hints about the technique on the web. The idea is to
>operate the filament/cathode at ground potential and connect the grid to
>about +250V so the cathode and grid act as a diode. In a real ion gauge,
>the diode current is limited to a few milliamps by controlling the power
>to the filament.

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I about had a heart attack when I read the above before I realized 
you meant to have the filament power either off or very low. If the 
filament was fully warmed up when you apply the +250 to the grid, 
there would be no further need to test the tube. :-)

73, Bill W6WRT