John Smith I wrote:
What would you offer as to the "photonic-jump", the capacitance of the
adjacent turns with air serving as the dielectric?

When electrons are accelerated in a conductor, they
emit photons. Some photons are emitted from one turn
and migrate to the adjacent turn. One might think of
it as a few photons taking a shortcut. Another way
of saying the same thing is that the fields couple
turn-to-turn. The overall effect is to increase
the velocity factor of the coil by something like a
factor of two over the "threaded bolt" calculation.
However, the effect is still magnitudes too low to
explain the 100 turn, 3 nS coil delay described by
w8ji.

Standing wave current cannot be used to make valid
measurements about current amplitude "drops" across
or phase shifts through a loading coil. One must
instead figure out a way to get a traveling wave
flowing through the coil. Then the phase shift
becomes perfectly obvious.

I have taken Wes's helical coil from:

http://www.k6mhe.com/n7ws/Loaded%20antennas.htm

and modeled it with EZNEC. I then loaded the coil
with a 1250 ohm resistor to minimize reflected current
and took a look at the phase shift through the
coil. Turns out to be about 37 degrees at 7.15 MHz.
That makes it a delay of about 14.4 nS.

That coil512.EZ file can be downloaded from:

http://www.w5dxp.com/coil512.EZ
--
73, Cecil http://www.w5dxp.com