"JB" wrote in
:

The accuracy of a Bird for measuring power goes out the window for an
SWR other than 1:1. Are you saying that if you put an unterminated 3

If by "measuring power" you mean determining the average rate of flow of
energy past the sensing element, you are not correct. The power can be
calculated as the indicated 'forward' power - indicated 'reflected'
power.

This is a property of any directional wattmeter of this type when the
sensor is calibrated for an impedance that is real (ie non reactive),
irrespective of the load or the type of coax that might be attached to
either side of the instrument.

Of course, practical circuits are not ideal, and errors are introduced in
all measurements. Some ham grade instruments are even less perfect.

The reason that Bird suggest that you can get an answer for power for
VSWR 1.2 by ignoring 'reflected' power, is that 'reflected' power is
less than 1% of 'forward' power and ignoring it does not introduce
significant error compared to other system errors.

Owen