On Sun, Sep 19, 2021 at 09:15 AM, Jim Lux wrote
The other thing that can trouble you unexpectedly is that for a lot of
antennas, the coax is part of the antenna system (either by design, or
happenstance).
kk7xo is measuring a J-Pole. Those antennas are famous for radiating on the outside surface of the shield and need good RF chokes.
Something to consider when calibrating at the end of the coax (or not).
Roger
Roger Need