> From: Rich Measures <measures@vc.net>
> >question2: It is my understandiung that the net output power as I
> >reported above ie 1800 fwd, 300w ref (birdetc) is 1500 watts? Correct
> >or not??
>
> Not correct. Wattmeters are calibrated for a 50 +/- j0 ohm load. If the
> load is other than that, the readings are bogus.
>
> Rich---
Your reply is incorrect Rich.
True directional couplers, such as used in the Bird wattmeter, remain
calibrated very well in spite of impedance excursions.
The method of subtracing reflected power from forward power is
perfectly acceptable, as long as the user remembers the tolerance of
a Bird 43 meter is +- 5% of FS anywhere on the scale.
You can find this described in many publications, as well as Bird's
literature.
73, Tom W8JI
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