Ed wrote in
. 192.196:

....
Apparently well enough to cause a problem. Its now 9 days
later from the above comment, and I see today that the original poster
followed my suggestion to install a balun which has solved his problem.

Ed, that defines how you define the problem.

If the problem was different measurements, that was caused by disturbing
the thing that was measured.

The different measurements hints another possible problem, common mode
feedline current. The baluns have changed the effect of those, and
probably differently at different frequencies.

But fundamentally, it is wiser to preserve the common mode current path
(even if you reckon the baluns help to reduce it) when making the
measurments.

The whole exercise demonstrates that the measurements from shack were
valid, it was disconnecting the feedline and making measurements at the
feedpoint that was invalid. (BTW, the measurements in the shack should be
done with the shield path connected as normal.)

A good example of the limited thinking in the proposition that you can
only make valid measurements at the feedpoint.

Owen