[Amps] 3-1000Z Filament Voltage Question

[Joe Isabella]

It's most likely the greater plate voltage causing the higher output, not the .04V of fil V.  I run my 3-500s at ~4.9 V with almost 4000V on the plates and I get 2kW+ with 110W drive.  I wouldn't fool with the filament V -- you'll drastically reduce the life of the tube if you get it too high, and you can still get full output with slightly lower fil V.
 
Joe, N3JI


Dennis Sokol <dajs at accnorwalk.com> wrote:
I have a BTI LK-2000 using a 3-1000Z operating on 160. I can get 1250 watts out with 2700 volts and 750 ma key down. The tube seems to be limited in current draw. I have seen more power out at a different QTH with higher line voltage.

I have measured the filament voltage at full load to be 7.08 volts.
This is a bit low from the spec of 7.13 to 7.87 volts. Is the low filament voltage a possible cause of reduced power out?

There is a 208 volt tap on the filament xformer but I would have to put in a dropping resistor in the primary to bring the voltage down to 7.5 volts. Is it worth the effort? Am I hurting the tube with the lower filament voltage or am I extending the life?

Thanks and 73,
Dennis W0JX Milan, OH
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