Bob wrote in
:

....
Another question -- I'm thinking of cutting a 10-foot section of
balanced line to test. Should I count the bared pigtails of the line,
which I will attach to the analyzer's coax output, as part of the 10
foot length? Or just count that part of the line where all insulation
is in place?

What you have is two transmission line sections in cascade, one with bare
conductors, and one with the conductors immersed in insulation.

If you want to measure the effects only of the latter, you need to find
some way of minimising the contribution of the former.

The calibration of the MFJ269 is not that flash that you will pick a mm
or two. When I have used them for the test you are performing, I zip tie
the conductor to the external threads of the connector so that there is
as close to zero length of 'different' transmission line as possible. You
could also use a small stainless hose clamp, but in my experience, the
zip tie has been reliable.

You can zip tie a piece of PE irrigation pipe to the VFO knob so that you
hand doesn't need to be within half a meter of the instrument, use a
wooden table to support the instrument, use the balun I suggested, and
arrange the line to minimise radiation from residual common mode current.

I would try to measure a length of 10m or so. It is a compromise between
making end effects (tails, effect of the windows) insignificant, an
effective balun, and physically supporting the line for least radiation
and other external influences.

Some of my focus was on trying to get a valid measure of R as well as X,
R due to line losses alone.

Owen