Cecil,

I will retain the entire message below, so that I am not accused of
misattribution.

Where did you get this idea that the velocity factor is constant?
Specifically, why is the velocity factor of a resonant coil the same as
the velocity factor of a significantly shorter coil? It is pretty well
accepted that the inductance of coils does not scale linearly with the
length of the coil. Therefore any arguments about based on direct
calculation of Vf from L and C would seem to fail to support your model.

I can think of two possibilities.

The first is that you treat this entire problem as a transmission line.
Most people would accept that the velocity factor for 200 feet of RG8 is
indeed the same as the velocity factor for 100 feet of the same cable.

However, the velocity factor appears to be the crux of your latest
argument about the behavior of a loading coil. It is not exactly
acceptable technique to include the desired answer as part of the proof.


The other possibility is that you are taking the lead from one of the
Corum papers. In particular, I am referring to the paper labeled:

"TELSIKS 2001, University of Nis, Yugoslavia (September 19-21, 2001) and
MICROWAVE REVIEW"

If so, I suggest you go back and reread what was written. He
specifically says (page 4, left column) that the equations for velocity
factor that show Vf as a function of diameter, spacing, and wavelength
apply only at resonance. The exact words a

" . . . an approximation for M has been determined by Kandoian and
Sichak which is appropriate **for quarter-wave resonance** and is valid
for helices . . ."

The emphasis on quarter-wave resonance was in the original; I did not
change a thing. The remainder of the paper clearly indicates that he is
talking about coils near or at resonance. There is no extension of the
Vf equations to short non-resonant coils. Indeed, he comments several
times that his model smoothly joins with the lumped circuit model for
smaller coils. That would require a non-constant Vf.

You attempt at decomposition of a resonant coil into smaller
subcomponents simply fails.

This is not an "ignorant diversion". If you have a third method of
supporting your claim of constant Vf, let's hear it.

73,
Gene
W4SZ

Cecil Moore wrote:
Gene Fuller wrote:

Cecil Moore wrote:

Gene Fuller wrote:

So you think adding turns to a coil is a nice linear process that
allows you to then subdivide the resonance effects according the
number of turns in each subsection?


That appears to me to be the most valid measurement that we
can make of the delay through a coil. If you have a better
way, please present it.


C'mon, you know as well as anybody that inductance of a coil tends to
increase as n-squared. Yes, there are all kinds of special cases and
correction factors.


Increasing the length of a coil or transmission line doesn't
change its velocity factor at a fixed frequency.

Adding turns and then pretending everything is nice and linear,
thereby allowing decomposition into subcomponents, is just plain silly.


Velocity factor is *nice* and linear, i.e. it is constant.

Please stop these diversions. I'm sure you are not that ignorant.