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Vintage threads from the first ten years
Re: Cathodyne PI
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 6/2/2000 3:31 PM |
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Ray Ivers |
Re: Cathodyne PI Momo, Ran the numbers - learned a lot. I initially planned to suggest the 12DW7 in addition the other tubes you mentioned, but TubeCAD doesn't like those tubes for this application. Apparently the only tube that will work easily in this scenario is the 12AX7 - the others all wanted a PI grid bias voltage that I feel was too low for proper operation of the gain stage (the 12AT7 came close, but was pulling less-than-optimum current). Here's what I came up with: Gain stage: 180K plate resistor, 1K cathode Split-load PI: 120K plate/cathode Bias voltage: @ 116 volts on GS plate/PI grid PI signal swing: +60 / -120 volts peak These numbers should make a fairly good starting point for you, anyway. Ray |
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