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[AMPS] vom check of 3-500Z tubes

To: <amps@contesting.com>
Subject: [AMPS] vom check of 3-500Z tubes
From: W8JI@contesting.com (Tom Rauch)
Date: Fri, 5 Oct 2001 10:28:31 -0400
> my amp supply lk-500 zb did a funny thing a while back when I powered
> it up after a long time in the closet and a cross country move.  so
> far I have found a blown 1 ohm, 5 watt wire wound resistor.  it was in
> two pieces so there is little debate on whether or not it blew...

Most likely you have a gas problem with the tubes. That is normal 
for tubes that sit a long time, especially tubes that might have had 
the seals operated at elevated temperatures prior to sitting.

You can not test that with a VOM. You need  a high voltage tester.

You should have a breakdown of 11kV or more from anode to grid 
in a good 3-500Z.

The grid is the offset pin, and the two adjacent pins. The remaining two pins 
are filament.

> one area that was suggested as a potential problem was an internal
> short in one or both tubes.

Yep, and it most likely is gas.
 
73, Tom W8JI
W8JI@contesting.com 

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