[AMPS] Checking out old amp

Jerry Flanders jflanders2@home.com
Fri, 16 Nov 2001 12:59:07 -0500


Should I worry about damaging the output tube?

I need to power up this old 5CX3000A pentode amp in a limited way to 
proceed with my checkout. I am nowhere near to applying HV and drive yet, 
but think I have the bias and SG supplies operational and need to check out 
a few voltages and circuits. There is a ton of supporting/protective 
circuitry that I want to observe and try to understand (no schematics).

I am concerned about powering up the main tube because I read warnings 
about operating without plate HV, but perhaps this doesn't apply as long as 
there is no drive.

As far as damage to the big tube is concerned, should I be worried about 
damage to it if I power up all but the drive and HV? I KNOW I have bias on 
grid 1. I am not sure the screen grid actually has voltage until I smoke 
test, because it looks like that circuit is awaiting some relays to pull in 
that probably will in this next step. Any tips/advice/whatever?

Thanks

Jerry W4UK


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