[Amps] Re: SB-1000 problem

[Roy Koeppe]

Re:

"I've got a Heathkit SB-1000 KW amp; uses a single 3-500z. It's got an
original Eimac. The unit hasn't been used in about six years. I brought
the
caps up on a variac fine. With the tube removed (running on 240) the
unit
fires up fine - the high voltage meter showing about 3350 volts.

The problem comes when attemting to start it up WITH the tube. It blows
the
fuses (10a in each side of the line) every time.

Two things come to my nearly virgin (to amps and troubleshooting) mind -
a
short in the tube, which I think is unlikely; or the tube just needing
"burned in"; hooking up the filament to ionize (??) it properly (this
last a
suggestion from a local ham).

Any ideas about where to begin looking? I have the manuals and can trace
a
circuit, but really have no idea where to begin."

Thanks,
Brad
K0BHC

Brad,

The tube is likely gassy and/or shorted between grid and filament. Can
you see the tube as you turn on the power? It may glow purple for an
instant! Try burning the filament for 8 hours with no HV.
Luck & 73,      Roy       K6XK