Roy said:
> Accuracy is essentially that of the voltmeter, typically 3 percent.<
Have you calibrated that?
For Type Approval testing, many standards call for the measurement of power to
+/-0.75dB for a measurement certainty of 95%. That's in a certifed laboratory,
with traceable calibrations, and works out to +/-18.9%. Now if it is that easy
to measure to 3%, why don't the standards call for better?
For radiated power, a measurement to 95% certainty requires +/-6dB - a value
detrmined by taking aknown tx and antenna round a string of certified labs and
measuring. Frightening.
The most fundamental way of measuring power must be calorimetric. I believe
that if you have a thermally insulated load and use it to heat water, and
repeat with DC in the load to get the same temperature rise, (with constant
ambient) you can probably get within a few percent....
73
Peter G3RZP
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