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[HAMHOCK75]

This data was taken earlier with a tube type Ameritron AL84 amplifier and an Icom 2KL solid state amplifier.



To show the change in power dissipated by the devices as a function of output power, the following was calculated.

Pd = Pdc - Prf, with eff ( efficiency ) = ( Prf/Pdc ) * 100

Pd = Prf * ( 100/eff -1 )

where Pd = power in the devices, Prf = output power, and Pdc = DC input power



Since class AB amplifiers are bounded by the theoretical class A and B curves, there seems little benefit to reducing power as a means to lower power dissipation in either tubes or transistors unless other means such as lowering the power supply voltage is used.

[K6AER]

Your filament wattage will effect the efficiency curve at low power out on the 3CX1200.

Bur then again you will never blow out a 3CX1200 due to VSWR.

[KH6AQ]

To calculate Solid State class AB amplifier efficiency at reduced power:

(PWRfull %) x (PWRreduced/PWRfull)^0.5 = PWRreduced %

example

56% x (50W/100W)^0.5 = 56% x 0.71 = 40%

[HAMHOCK75]

KH6AQ, I plotted your equation for efficiency of class AB to provide these three ideal curves for class A, AB, and B.



The measured efficiency of the Icom 2KL was plotted against ideal these curves. The fit was remarkably close.



These are theoretical curves for power dissipation vs. output power.



Added to the three theoretical curves is the calculated dissipation from the efficiency data for the Icom 2KL.