Hi there. I am using 3CX1200A7 tube in homebrew grounded grid service. I
have a vacuum relay switched multiple-tapped secondary plate transformer
with 3000, 3500, and 4000 VDC at full load. Theoretical calculations show a
PEAK impedance of about 94 ohms at the cathode when operating with a anode
voltage of 4000 VDC nominal. However, calculating the average cathode input
impedance with the three given plate voltages has me at a bit of a loss. I
am re-doing my Pi input network and need to ballpark the Rc to work
reasonably well on all three plate voltages with a chosen network Q of 4. I
am aware of the published average cathode input Rc of 60 ohms for a plate
voltage of around 3500 VDC nominal. Is there a MatLab bit of software
available to run out the integral for average cathode impedances with
different plate voltages?
Any insight/help would be appreciated. Thanks!
73, Paul WN7T
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