[Amps] Re: 3-500Z tubes

[Roy Koeppe]

Re:

"The 3-500Z tubes in my AMP INT 3-500ZC amplifier are shorted between
filament and grid.  There may be more wrong but this is a start.

Question.  What is my best source for obtaining the 3-500Z tubes?  Are
Eimac tubes still available?  Do I want the ZG with the graphite anode?
Will the G require any changes in the amp?  Do I need a matched pair?
What about non-USA made tubes?"

Thanks again,

Bee, K4JLD

Hi again, Bee,

(I won't say 'I told you'!   :-)  )   I buy my 3-500ZG tubes from...
www.rfparts.com   with excellent results from their own brand. They sell
other brands as well. Also, there is www.tomstubes.com whom I have not
yet purchased from. My Eimac '500Zs were notorious for having your
problem. I'd never buy them again. Yes, the ZGs work as a direct plug-in
replacement. I consider them far superior. RF Parts sells them all in
matched pairs, which you DO want. Those are all non-USA, of course, and
are fully warranted. RF Parts wants you to burn them in for ten hours in
standby before operated them at power out.

Good luck & 73,     Roy   K6XK/0