Roy, W7EL wrote:
"Just a couple of hours ago you said the current would have to wind its
way atound each turn, following the wire from one end to the other, and
it would take nearly the wire length divided by the speed of light."

Yes, and I`m still convinced that is the case in an air cored r-f coil
that is long because the coupling between ends of the coil isn`t enough
to bypass the delay of the coil.

I posted speculations on bypassing the delay in the coil. Capacitance
between turns is too small over the length of the coil, said to be about
one loot, and about 100 turns.

Tom, W8JI had said that magnetic coupling between the start and finish
of the coil bypassed the time delay of following the path of the wire.
Well, nothing happens instantly when voltage is applied across a coil.
90-degrees after the voltage has crossed the zero axis on its way up,
the current does the same. It lags the voltage by 90-degrees. It`s the
current which induces a voltage in the coil and this is delayed by the
forces predicted by Lenz`s law. 90-degrees at 4 MHz equates to about the
time required for a radio wave to traverse about 60 feet of thin wire.

100 turns of wire on a 2-inch form requires about 52 feet of wire. The
current travels from start to finish on the coil before the current
reaches its maximum in the coil and before energy could be effectively
induced from one end of the coil to the other. The wave velocity is
about 984 feet per microsecond.

These are just musings aloud and confirm my speculation that signal
progress is through conduction on the surface of the wire of the coil.

Best regards, Richard Harrison, KB5WZI