[Elecraft] wattage on k3 vs kpa500

[Ron D'Eau Claire]

I believe an ATU or other matching network provides a conjugate match. That
results in optimum power transfer because the RF current and voltage are in
phase and the SWR meter will read 1:1.

When there is a mismatch, as indicated a high SWR, the finals in the rig do
not see the optimum load impedance for efficient power transfer so they do
not operate at optimum efficiency. Lower efficiency means that more of the
d-c power applied to the finals is consumed in heat instead of RF, and the
amount of heat the finals must dissipate goes up. I believe that's what led
many Hams to mistakenly believe that the "reflected" power was being
absorbed in the finals.

The solution is, of course, to provide a proper termination for the finals.
When the antenna or other load doesn't present the right impedance, a
matching network (a.k.a. 'tuner' or ATU) can be inserted to provide one.

Ron AC7AC



-----Original Message-----
Most likely the K3 is putting out 60 watts, real watts.  The wattmeter is
also probably correct reading 80 watts forward, with 20 reflected, equal to
a net 60 watts.  And 60 watts is radiated by the antenna.  No power get
reabsorbeds by the amp because it is presenting a congugate match.  i.e. any
power coming back from the  antenna sees a perfect mismatch at the
transmitter and gets re-reflected back to the antenna.  Explained 100 times
better than I can by Walt Maxwell in his books "Reflections"  or maybe the
current one is "Reflections III" something like that.  Anyway the point is,
none of this rf power heats up the finals.