Power output is notoriously difficult to measure.? To measure power out at one frequency, using an SA is probably the only way as you suggest.
But then, the SA has a Spec for level, typically +-1dB say, for the HP8560A I have. And unless it's just been calibrated, even that is of course,? suspect.? Calibration in my experience simply means that the instrument being tested falls with it's specification, not that it's absolutely accurate.
Then there is the problem of measuring the attenuators required for higher level power measurements.? An attenuator "checked" using an uncalibrated SA is also suspect.
Take a measurement of a? 10W? signal (+40dBm)
It could be +39dBm = 9.9W
or +41dbM = 12.6W
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On Fri, May 18, 2018 at 10:23 PM, ajparent1/KB1GMX wrote:
The check would be you must be putting st least 2A into (24W to the finals, ~50% efficiency)
the finals to be in the 10-12W region.
I don't ever believe scope readings as accurate. For power out I use a dummy load with a
diode detector or a 30-40 db power attenuator as I have a calibrated unit 30db and 10db
that into the spectrum analyzer gives good reading for power.? If all else fails if my 10W
dummy gets hot its likely more than 10W.? The latter with a thermometer can be calibrated
for power equal temperature using a variable power supply (DC power=RMS power).
At some point you need an instrument you can believe.
Allison
