dansawyeror wrote:
Now that the setup is reading consistently I will 'test' a loaded 2m
monopole over a 1 m**2 ground plane.

I suggest that you start with an unloaded monopole or some very simple
antenna with a well known impedance. (You will of course have to know
and allow for the effect of the finite ground plane.)

You also need to take measures to prevent coupling between the antenna
and the outside of the feedline. The ground plane you mention will help,
but there can still be substantial coupling. Some high impedance ferrite
beads at the feedpoint and another set about a quarter wavelength down
should reduce the coupling to a small value.

Roy Lewallen, W7EL