Rich,
you say
>However if Zout is 50 ohms and the load is 50 ohms, the efficiency is
>50%, not the 62 or so percent that we typically see. It seems to me
that
>62% efficiency would mean that Zout was 30 ohms.
>Rich...
When we were discussing this matter here a few weeks ago, Tom indicated
(although I may have misunderstood him) that the the output impedance is
a 'non dissipative resistance'. Under those circumstances, the
efficiency would be different.
I can see that feedback alters things. Consider a power supply that
drops 100mV when 1Amp load is placed on it. We can accept that it has an
internal impedance of 0.1 ohm. If that power supply is a 12volt 1 amp
unit, it would be matched if loaded with 0.1 ohms. However, 1 amp in 0.1
ohms is 0.1 watts, while 1 amp in 12 ohms is 12 watts. So matching in
this case doesn't give optimum power transfer.
Is it unfair to suggest that similarities occur with AC genereators, and
thus tubes, and transistors?
73
Peter G3RZP
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