[Amps] Bird accuracy, etc.

[Peter Chadwick]

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