>A power amplifier can be reduced to the Thevenin
>equivalent circuit of a voltage source with a
>series resistor source impedance. Power transfer
>is maximized when the load impedance is equal to the
>source impedance.
Yes - IF the power is available. But at the conjugate match, the power
may well not be available or, in other words, the source impedance
changes. Like the lab PSU that has a 0.1 ohm output impedance at 12
volts, but current limits at 1 amp. So the maximum power you can get out
of the box is 12 watts, and at that, if you reduce the current drawn by
100mA, you get 12.01 volts but only 10.8 watts. With a 0.1ohm load
providing a 'conjugate' match you'd only get 0.1 watt. (1amp in 0.1 ohm)
73
Peter G3RZP
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