On Tue, 28 Nov 2006 16:24:07 -0500, John Ferrell
wrote:

What I expected to see was some thing resonant between 6-8 mhz with a
lot of reactance and who knows resistance. It did not happen....

Hi John,

It is hard to imagine your antenna showed a strictly resistive,
non-reactive load over that interval where the radiator is only a
quarter wave at best. Fed at the base it should have some capacitive
reactance until resonance somewhere near the 40M band. Fed with a
wire at the height you indicate should show an inductive reactance
over the entire span.

What I did see was a resonance at 23 mhz with Rs= 48 and Xs=5 for a
1.1 SWR!

Sounds like your antenna base was not connected to the radials (you
were driving the antenna through the length of the gamma wire, and the
structure above it).

So that leads to my question: How do you shunt feed a 28 foot
vertical?

For 80M? About a 1000pF in series with the added wire. This still
says nothing of the resistance being sub 1 Ohm IFF your gamma wire is
on par with the diameter of the vertical element. On the other hand,
if it is very much thinner (and using half the capacitance), it stands
to elevate the resistive portion (to 30ish Ohms) into a match.

A more complete specification would tighten up the variability in
this.

73's
Richard Clark, KB7QHC