I am re-building an Advanced Radio Devices amplifier with 3 x 3CX800. The
is designed to run on 4 fixed frequencies, thus the PI-L tank circuit and
input circuit needs to be re-designed to accommodate the amateur bands.
To determine the "operating line" I need the constant current characteristics
of the tube.
Do anyone know where data can be found?.
Is it still possible to obtain the Eimac "tube performance computer" mentioned
Eimac's care and feeding of power grid tubes?, or do someone have any software
to do the job.
Or simpler (for me!) , do anyone know the optimum load impedance, running each
at full rating in class AB2. Plate voltage will be around 2300-2400V at full
I also need some info on the input impedance. To me it looks like the input
is going to be fairly low (15-16 ohms), making it more difficult to match with
pi-network. Could it be an advantage to use a PI-L or an other network in the
I have compared Eimac formulas with the output data from KD9JQ's TAP2-program.
calculation of the tank-circuit works fine, but the load resistance is not equal
to peak RF-voltage/peak fundamental RF current. The difference is a factor of 2
Also the input-circuit calculation is wrong ( Rin > Rgrid ).
KD9JQ uses the tubes Grid impedance as reference for the PI-input circuits Q.
I believe that Q = Rin/XCin, where Rin is the source resistance (transmitter,
Do anyone have experience in rebuilding an Advanced Radio Devices, ARD-230M?
All comments would be much appreciated.
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