In a message dated 2/29/2008 3:04:05 P.M. Eastern Standard Time,
wlfuqu00@uky.edu writes:
You can't simply
tune out the capacitance with inductance and say you have no power loss
on the input of the device. 5 or 10 percent drive power compared the output
lowers the overall efficiency by another 5 or 10 percent.
That 85 to 90 percent efficiency could just as well be 75 to 80 percent.
More like a class-C tube amplifier.
73
Bill wa4lav
Hi Bill,
There is some non-linearity to the capacitance of the Mosfet when
driving the gate due to Miller effect. The peak driving power may be 20-30
watts but the average driving power may be only 5 watts or less for a
kilowatt
Class-E amp on 160 meters. 5 watts driving power is 1/2 of 1 percent drive
power for a kilowatt-input Class-E amplifier. How does that lower efficiency
by
up to 20%?
73 Todd WD4NGG
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