[Amps] 4CX1500B help needed...high screen current in HF-8020 PA

Paul radioboy at telus.net
Mon Jan 14 21:11:07 EST 2013

Hi all,

I dug into it again today and FINALLY found where the screen I is measured.
It's in the PS manual, not the PA. I found the current is measured in the
ground leg of the screen supply thru a 383R. It's opamp based and I haven't
traced it beyond this yet but at least I found it. 

I had 3 or 4 fellows suggest that the tube may be gassy, and to run it with
operating voltages but no RF drive. I tried this for about 3 hours today and
so far and the current is down to half of what it was. Yeah! Hopefully that
is it. I'm going to run it for 3-4 more hours to see what happens, then
maybe overnight.

Thanks again for your help everyone.  I'll let you know tomorrow, the


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