) writes:
Reg Edwards wrote:
=======================================
All power amplifiers have a tuned circuit in the plate. It is
essential to reduce output power contained in the harmonics.

In any case, power in the harmonics is wasted power.

With a tuned circuit in the plate it is impossible to achieve a
rectangular voltage output waveform. It is always a sinewaveform.

A rectangular plate current in conjunction with a tuned load always
causes harmonic power to be wasted at the plate.

So one might just as well use a sinusoidal driving waveform, Class-C
or not. It's easier. It also avoids generating and wasting harmonic
power in the driver.


Not true.

A network with an inductive input will allow a square waveform at the
device output but not waste significant energy in harmonics. I've done
that in designs.

And the point is that the Class-C only conducts on a portion of
that sinewave anyway, requiring that tuned circuit in the output
as a "flywheel" in order for there to be a sinewave at the output.
The "harmonics" are a byproduct of that non-linear conduction
at the input. And of course, that's why an amplifier could easily
become a multiplier simply by tuning the output to a harmonic of
the input signal.

Michael VE2BVW