Got a Johnson Desk KW and notice something unusual about the design.
The RF amplifier has a linked variable capacitor and inductor in plate PI
output circuit which switches out the variable capacitor for frequencies
above 13MHz. So the PI output ckt from there up made of the
plate-ground capacitance the roller inductor and output capacitors. I
have only seen this sort of thing one place before in a Mil. transmitter
with a pair of 4CX300s in it. It had switched fixed capacitors for plate
side of the PI network, variable inductor with a few switched inductors and
variable output capacitor with some switched fixed ones.
Well anyway, has anyone had some experience with the desk KW
amplifier? And have anything to say about the PI output? network?
73
Bill wa4lav
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