Steve Nosko wrote:
"It is as simple as the fact that it is not internally resistance
limited----."

We are discussing maximum power transfer which by definition is the
condition in which all available power is delivered to the load. This
condition requires equal resistances in source and load.

Maximum power transfer can be found by varying the resistance used as
the load until the load resistance is found which generates the most
heat. This assumes there is no reactance or other opposition to power
other than that of the resistive type in the source and load.

Once you`ve found the load which extracts maximum power from the source,
measure its resistance. That is also the resistance of your source.

In the Class-C amplifier, some of the source resistance it presents to
the load is of the lossless variety. Were it all of the dissipative
variety, just as much heat would be generated within the amplifier as
within the load, UNDER MAXIMUM POWER TRANSFER CONDITIONS. Some of the
internal resistance is the lossy kind. The final amplifying devices have
almost full on or off states. There`s little transition, and the
saturation voltage is low but not zero. The lossless variety of internal
resistance comes from an average of the switched-off time of the
amplifier.

My example presumed a 50-50 spllit between dissipative and lossless
resistances in the Class-C amplifier. That made an efficiency of 66.7%.
Not bad and not unusual. That`s the way it works, believe it or not.

Best regards, Richard Harrison, KB5WZI