Cecil Moore wrote:
Tom Donaly wrote:
What's the Z0 of a loading coil, Cecil?

Z0 and VF depend upon the geometry of the coil
*and the frequency*. A 75m Texas Bugcatcher coil
has a Z0 of ~3800 ohms and a VF of ~0.02. The
coil that w8ji used for his 3 nS "measurements"
has a Z0 of ~5300 ohms and a VF of ~0.033. I've
generated an EXCEL file that does the calculations:

http://www.w5dxp.com/CoilZ0VF.xls

I've also got a web page that explains why the
current phase in a standing-wave antenna cannot
be used to measure delay.

http://www.w5dxp.com/current2.htm

I have done the suggested bench experiments myself
and the results are nowhere near w8ji's results.
When traveling wave current is used instead of
standing wave current, the delay is obvious on a
dual-trace O'scope.

This is nothing new. It is based on the information
in the IEEE paper which someone presented years ago:

http://www.ttr.com/TELSIKS2001-MASTER-1.pdf

Still using the Tesla coil fella's ideas, are you? A frequency
dependent Z0 is a good trick. What happens when you double the
length of the coil? Does the Z0 stay the same? What if the coil is
infinite? Can you make a quarter wave shorted stub with it? If you
make it a half wavelength long - keeping in mind the velocity factor -
will the impedance looking into the coil equal the impedance of
the load? How do you attach a load to it?
73,
Tom Donaly, KA6RUH