Cecil, W5DXP wrote:
"Actually, they are wondering how you are going to prove 100% coupling
between coil #1 and #100 in your 100 uH coil such that the result was 1
nS delay over that one foot length."

Yes. I think turn-to-turn capacitance doesn`t amount to much and won`t
bypass the coil as you have 100 small capacitors in series, so their sum
approaches zero.

The speed of the wave is almost 984 feet per microsecond. At 75 meters
(4 MHz), 1/4-wave is about 60 feet, and this corresponds to 90-degrees.
The delay corresponding to the time required to establish current in the
coil to induce voltage seems trivial to me. Almost instantaneous
transmission between the first and last coil turns should be possible
were they tightly coupled.

But, I think Cecil is on to something. I`ve played with antique radios
using front panel adjustment to control distance between two coils on
the same axis to control their mutual impedance. You only had a couple
inches of adjustment which was enough to seriously decouple the coils.
12-inch separation would surely have almost completely decoupled them.
This much separation was not available as I`m sure it is unnecessary.

Best regards, Richard Harrison, KB5WZI