"Richard Harrison" wrote in message
...
J.B. wrote:
"As soon as the load gets reactive, the phase between the voltage and
current are different and the length of the coax and its velocity factor
now contribute unless it is really short compared with wavelength."

The Bird wattmeter won`t affect tuning and loading of an antenna if it
is made part of a half-wavelength of line inserted for the measurement.
This may be important at VHF and higher frequencies. The inserted line
and its meter need to be specially tailored to make up a half
wavelength, if it is to be inserted in nonflat lines. For several
different frequencies, several line measurement assemblies are required.

Best regards, Richard Harrison, KB5WZI

Hence, impractical for multiband use, where the sampling line might just as
well be left in place and considered part of the whole line length even for
those times when you have to insert a 5K watt slug (because your 500 watt
amp pegs the 1000 watt slug) just so you can fully load for maximum forward
voltage with your Pi-Net.

Certainly useful for your 2m antenna being fed with surplus CATV hardline so
you can adjust the line length for a multiple and find a good SWR. But are
there still reflections? Yes.