I'm also thinking that without a noise-bridge, my best bet is a trial and
error comparison. Joe Carr sez that at less than 1 wavelength, large loops
can reach a feedpoint impedance of up to 3000 ohms (I had to read it twice
to make sure); but at a full wavelength or longer, it pretty much stays at
around 100 ohms. Various sources show anywhere from no match needed, all
the way up to a 30:1 match is needed. I think there's just too many
variables to know for sure. So, trial and error it is. I'm going to try a
30:1, a 10:1 and a 1:1 toroid xformer to see what differences, if any, I
can detect just with the naked "earball". In the absence of any
discernable difference, I'm going to at least use the 1:1, if only to
maintain the DC seperation between the antenna element and the coax.

In addition to the end Z varying radically with frequency, you will also
find the classic 9:1 toroidal transformer only functions as a 9:1 over a
relatively narrow frequency range- whereas a binocular core will behave as a
9:1 over almost 2 decades. Somewhere here I have a network analyzer plot
comparing a toroidal vs binocular transformer.


--
Dale W4OP
for PAR Electronics, Inc.