Cecil Moore wrote:
Tom Donaly wrote:

People who want to know what W8JI actually believes, as
opposed to what Cecil says he believes, should go to W8JI's
website.

I agree, Tom, and here is the URL:

http://www.w8ji.com/inductor_current_time_delay.htm

W8JI takes a 2" dia, 100 turn, 10 inch long coil, and
claims the actual delay through that coil is 3 nS or
4.5 degrees. (The formula for the velocity factor of
such a coil yields ~0.033 at 4 MHz making the actual
delay ~37 degrees or ~25 nS at 4 MHz.)

W8JI's mistake was using standing wave current to try
to measure that delay. The phase of standing wave current
changes hardly at all and is useless for measuring delay.

If the delay is to be measured by observing phase shifts,
then traveling wave current should be used. That would
require loading the coil with a resistor equal to its
characteristic impedance.

Another way to measure the delay is to set the coil up
as a helical antenna over a ground plane and find the
self-resonant frequency which would mean the phase shift
through the coil is 90 degrees at that self-resonant
frequency. Even though the delay changes with frequency,
it is highly unlikely to drop from 90 degrees to 4.5
degrees in a few MHz.

... your little theory about phase shifts across
loading coils, which you can't substantiate through experiment, or
even through any type of rigorous theory, is nothing more than
an exercise in philosophical fantasy.

Actually, it is an exercise in the physics of reality.
A 3nS delay through a 100 uH coil is the real "exercise
in philosophical fantasy" and obviously impossible. Try
it with a TDR and see what you get. Heck, try it at DC
and see what you get.

At his request, I sent a test setup schematic to one of
the gurus on this newsgroup so he could prove me wrong.
He has gone silent and stopped answering my emails. I
expect to see a paper or magazine article announcing
"his discovery".

What is the characteristic impedance of Tom's coil? How do you
define the characteristic impedance of a coil of wire? If you
were to replace Tom's coil with a shorted length of transmission
line, given that jXl = jZo(tan(BL)), which one of the infinite
combinations of Zo and L would you use, given that any of them would
resonate your antenna? Would they all have the same "phase shift?"
What's your formula for the velocity factor of Tom's coil? Is it from
the same Tesla coil crackpot you quoted in previous posts? Have you
used the test setup you mentioned, yourself? Spit out some numbers.
73,
Tom Donaly, KA6RUH

(P.S. For those who don't know: "B" is my version of the Greek letter
"Beta," and L is the length of the transmission line, so BL is the
length of the line in radians. In order for jXl to stay the same,
given a change in Zo, the length of the transmission line has to
change, too. Since the length isn't unique, the delay isn't either,
and even if Cecil's transmission line coil did act like a transmission
line, the delay could be changed to anything anyone wanted it to, just
by changing the coil dimensions. Of course, Cecil can't prove that his
coil is much of a transmission line, so the point is moot.)