|[AMRadio] GG 813 Linear in GE Ham News|
k4kyv at hotmail.com
Sun Oct 9 09:43:58 EDT 2005
>A standard carrier reading wattt meter (think 'Bird') should not move, when
>the carrier is modulated to 100%. A PEP reading wattmeter (it's my opinion
>that you can *not* find one that reads accuratly enough) willl only show
>that the rig -is- being modulated, but not if it is being over-modulated,
>causing distortion and splatter and being rather un-neighborly to others on
A field strength meter should not move when the carrier is modulated to
100%. It is designed to read AVERAGE carrier voltage. If the final stage
has good modulation linearity, the average carrier voltage doesn't change up
to 100% modualtion.
A true average-reading wattmeter will read increased output with modulation.
The power output includes carrier + sideband power. 1000 watts carrier
output should read 1500 (average, or mean) watts out with 100% sinewave
With a thermocouple rf ammeter in the line, the rf current at the output
should show a 22.5% increase with 100% sinusoidal modulation.
Many rf output meters actually read rf voltage output and therefore show no
upward kick with modualtion. An rf ammeter is a thermal device which does
not average the output, so it will show an upward kick with modulation.
Square the current increase to get the percent power increase.
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