>
>Richard W. Ehrhorn wrote:
>
>>Congratulations! But I suspect you can squeeze another 5-10% efficiency out
>>of it with more work. I mean, we're never satisfied, are we?
>>
>Efficiency is very hard to measure accurately, and the potential errors
>mean that he might already have another 5-10% in fact... or it might be
>5-10% worse.
>
>Typically Ep errors could be 2% full-scale on the meter movement and at
>least 1-2% on the multiplier resistors. Ip errors again typically 2% FS
>on the meter movement and about the same on the shunt. These DC
>measurement errors could be reduced to about 1% by calibration using a
>good DMM, but that still leaves at least 5% error on the RF wattmeter.
>
? Indeed, Ian, and RF wattmeters must operate into 50 +/- j0 ohm load in
order to read semi-accurately. . . [An ordinary DMM is a reliable
means of checking to see if the 50 ohms DC component is there. ] .
Rich...
R. L. Measures, 805-386-3734, AG6K, www.vcnet.com/measures
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