Reg Edwards wrote:
What makes you think your EXCEL spread sheet (whatever that is) gives
the right answers?

Because it agrees within 3% of my actual measurements.
It's the same formula covered by the BASIC program
that I emailed to you.

Have you ever made any measurements of the harmonic resonant
frequencies?

The posting to which you are responding has three of
those measured harmonic resonant frequencies.

If so, how did you do it?

I put the coaxial choke across my MFJ-259B terminals and
looked for low impedances. They occurred at 45.6 MHz, 88 MHz,
and 122 MHz corresponding to 1/2WL, 1WL, and 1.5WL. That
proves that the VF given by Corum's equation is correct
because it predicted the 1/4WL point at 22.5 MHz, within
3% of the measured results.

And if the Corum equation is valid for coaxial chokes, it
is probably also valid for mobile antenna loading coils.
--
73, Cecil http://www.qsl.net/w5dxp