Reg Edwards wrote:
The resonant frequency is due to the stray capacitance of the coil being in
shunt with the inductance.

Hi Reg, that answers my question. I'm glad you didn't go the
"lumped" route. Do you have a program that calculates the delay
through a real-world coil?

Incidentally, when the coil is only partly stretched out, the program can be
used to estimate the resonant frequency of "Slinky's". Never having had a
Slinky I cannot say precisely how accurate this might be.

Did you take into account that some Slinky's are made out of
plastic. :-)
--
73, Cecil, W5DXP