wrote:
I took the "Axial Propagation Factor" (4.372 rad/m) figure which was
given by the HamWaves calculator and multiplied it by the coil length
(155mm) to find the effective electrical length of the coil (38.83
degrees). Then I took cos(38.83)=0.779 as the fall-off in current
across the coil.

Interesting. W8JI's coil through which he measured a 3 nS
delay was 100t, 2" dia, 10" long, #18 wire.

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

Converting everything to metric and entering the data into
the HamWaves calculator at 4 MHz, yields a calculated delay
of 21.5 nS through the W8JI coil and a VF of ~0.04 at 4 MHz.

So which are we to believe? W8JI's measurements or ON4AA's
calculator. There's a 7x difference between 3 nS and 21 nS.
--
73, Cecil, IEEE, OOTC, http://www.w5dxp.com