[Boatanchors] OA2 CURRENT

Magoo magoo at isp.ca
Sun Aug 9 13:15:50 EDT 2009


I'm trying to troubleshoot what appears to be excessive current draw in a 
P/S employing a pair of OA2s.  With all tubes out of the chassis, 
approzimately 10ma is being drawn through the choke (in the ground lead) by 
the bias supply.  When both OA2s are plugged in (with no other tubes 
installed)  that current rises to about 90ma, and that seems excessive to 
me.  Both tubes test OK.....but are they?

B+ at source is 315 and each tube is fed through 4K; with no load I 
calculate 7 ma for the idling current on each tube.  Is my logic flawed, or 
am I dealing with a pair of tubes which test good but are actually bad?

Bill VE3NH 



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