Input vs. Output

[Doug Shields]

Tom,
     The difference in power ratings stem from the FCC laws of the time.
When I got my Novice ticket (and HW-16) in 1972 the rules were that Novices
could use a maximum of 75 watts of INPUT power to the final amplifier stage.
Thus the mark on the HW-16 meter that indicated 75 watts.  If I recall, the
maximum Amateur power level was 2000 PEP watts input or 1000 watts for CW.
    How much power you get out depends on the efficiency of the final
amplifier stage.  I never had a good wattmeter on the output of my HW-16 but
I suspect that 40-45 watts out would be about right.
     Some time later, I forget exactly when, the FCC changed the rules to
regulate OUTPUT power.  This is a lot easier to measure.  Just put a
wattmeter in your transmission line.  This is a lot easier to do in the real
world.
    From what I have observed, I would guess that the efficiency of an
average amplifier is from 60 to 70%.  I hope this helps.

Doug  W4DAS

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