In Reply to: RE: copper-plate GM70 posted by Tubenstein on December 27, 2011 at 20:33:19:
It's easy to calculate if you know the capacitances. Looks like the GM70 runs 12pF plate to grid, at a mu of 6.7, so Miller capacitance around 80pF. Just calculate the current into that reactance at 100kHz, for a peak voltage equal to the grid bias, and you have the quiescent current needed in the driver (assuming Class A1). Take the driver plate resistance against the 80pF to calculate the -3dB frequency, which should be above 40kHz to give less than 1dB loss at 20kHz.
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Follow Ups
- RE: copper-plate GM70 - Paul Joppa 20:54:40 12/27/11 (1)
- RE: copper-plate GM70 - Tubenstein 21:59:35 12/27/11 (0)