I have a GS-35B Bias question.
I constructed a 2 tube GS-35B amplifier; it has separate filament transformers
and bias systems for each tube. My transformer runs 4200 VDC unloaded; I set
the Zsac for each tube separately, I have each tube running at exactly 425
mills at idle. At 425 milliamps, the X-former drops to 3900 VDC (with one tube
disabled by removing cathode fuse). Both tubes are set to draw the same
amount of current.
When I put both tubes in service, instead of getting 850 mills of Zsac, my idle
current is 740 milliamps and my B+ is at 3750 VDC.
With RF drive the B+ dropped to 3375 VDC @ 2.0 amps and delivered around 4000
watts output; at increased drive levels, the B+ did not drop any lower than
3375, it (the X-Former just drew more current from the mains; I took plate
current up to 3.5 amps and B+ held solid).
What’s the optimum level of bias to run on a GS-35B and, based on my
observations, should I crank my bias up a little higher in setup knowing that
when the 2 tubes are run together they drag the B+ down which changes the
affect of the bias setting?
There is a lot of information at GS-35B DOT com but, I would really like to
hear from someone with recent experience on their construction / conversion
using the GS-35B tube.
koØm
http://www.network54.com/Forum/142608/
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