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In Reply to: Very common 300B operating point posted by Chris O on February 23, 2007 at 04:52:26:
My calculations are 435 B+ ,68 volts at the cathode , through a 833 ohm resistor = 81.6Ma , so I have 367 volts across the tube @ 81.6Ma = 30watts, I feel this is high for mesh plates, I know I can drop the current by raising the cathode resistor, but my main question was, is it better to drop the B+ on the entire circuit or just raise the cathode resistance to lower the idle current, I was worried about changing the operating points on the driver section if I lowered B+
Follow Ups:
In general tubes are more linear at the higher end of their voltage ratings.
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Long Live Dr.Gizmo
I just experimented with a working amp I have I ran my Shughang meshplates on 437 volts B+ with a 1K ohm resistor, ended up with 69 volts across my 1K, So It ended up I am running at 25.392 watts. I also noticed that the blue glow was not a square patch on either side of the tube but a slight blue glow over the entire envelope, Plates look fine but hard to tell with the plate perforated. This Is my first single ended building experience so I am not familiar with the ins and outs. What do you think? I think I am where I should be
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Long Live Dr.Gizmo
Thanks for your replys
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