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...
one area that was suggested as a potential problem was an internal short in
one or both tubes.
I pulled them and did a vom check for short vs open across all pin
combinations. both tubes are eimac 3-500z
if one looks at the bottom of the tube with the plate away, there are 5
pins. one is by itself and the other 4 make up the rest of the array. I
see short (0 ohms) from the pin by itself and its two neighbors and open
between any of these and either the plate or the other pins. I see short
between the remaining 2 pins and open between these and either the plate or
the other pins.
when I say short, I mean 0 ohms as measured by my cheapo radio shack digital
vom; not sure I could tell the difference between 0 ohms and the resistance
across the filament which should be some small number.
I would guess that the 3 pin set are connections to the grid and the 2 pin
set is the filament.
so from a low voltage standpoint, it does not look like there is a short
between either the filament or the grid and the plate nor between the grid
and the plate nor between the filament and the grid. maybe at 3000 vdc,
things change...
comments?
jim
N1NK
x AB6R
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