John Popelish wrote:
We are not talking about L, C, R, or any other inherent property
changing with frequency.

The velocity factor of the coil is based on those quantities
and can be calculated.

The velocity factor of a transmission line is based on those
quantities and can be calculated.

Freq 1 2 4 8 16 MHz
Delay ___ ___ 3 ___ 16 nS

That looks non-linear to me. How about you?

Definitely nonlinear, just like impedance is very nonlinear as the
frequency passes through any resonance.

Care to fill in the blanks above?

This is why I am suspicious of
a measurement made at resonance, being extrapolated to non resonant
conditions.

Self-resonance is simply where the round trip delay through
the coil puts the forward and reflected voltages and the forward
and reflected currents either at zero degrees or 180 degrees.

That's what happens at an open-ended 1/4WL stub.

That's also what happens at the feedpoint of a resonant
standing wave antenna like a 75m mobile bugcatcher antenna.
Resonant mobile antennas are "self-resonant antenna systems".
--
73, Cecil http://www.qsl.net/w5dxp