JIMMIE wrote in
:

....
True enough, but checking SWR isnt my main concern I can interpolate
that well enough. I was just wondering if my idea for measuring power
via a calibrated full scale adjust dial would be a valid procedure.

You could do it the way you describe. The question is not whether it can
be done, but rather what the expected error is. Meausuring RF power is a
challenge, and adding the potentiometer setting as a variable element
adds error. That was a weakness with the Oskerblock sheme I mentioned
earlier.

I don't really understand the issue with the meter. I see meter movements
on Futurlec for $10.

An alternative approach is to use a DMM with a lookup graph to
interpolate detector voltage to power. So, you put a jack on the
instrument to pick of the DC from the fwd and rev detectors, and do up a
cal chart relating that voltage to power.

I have added a 1/4" TRS jack to a commercial VSWR / Directional Wattmeter
doing just that, and have created a cal chart in a spreadsheet that
allows cubic spline interpolation for high resolution power measurement.
Whilst improving the resolution doesn't improve absolute accuracy, the
high resolution capability is really handy for some tests.

An article describing the technique is at
http://www.vk1od.net/measurement/irpm.htm , and it includes a link to the
spreadsheet which has the cubic spline interpolation feature.

Owen