[AMPS] AL811H saga continues

[Scott Bullock]

Time to draw on the collective wisdom of the amplifier gods again....



I got the new Svetlana 811a tubes from RES in today and dropped them in tonite, but still can't get full power out of the amplifier. I can load the amp up with up to 200ma grid current, 450 ma plate current and 1500v high voltage, but the most I can get out of it is 500 watts cw. 


I originally thought that maybe because of the plate to grid short in the original tube that maybe there was something wrong still in the driving section on the tubes, ie a bad cap or something, so I pulled out 2 tubes and could still get the same amount of power out of the amp, so then I pulled 2 diagonal tubes out and did the same test and got the same results. 


So this rules out that there is still a problem with grid resistors/series blocking caps etc. Going from 2 to 4 tubes only changes the output by 5-10 watts, and doesn't change the plate/load tuning much at all either.



Help! Anyone got any ideas besides send it back to Ameritron? This is a last resort option, as I really don't want to ship this.


Thanks in advance,


Scott


KA1CLX



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