wrote:

Cecil Moore wrote:

Guess everyone sees the danger in trying to guess what
the results of someone else's measurement will be. Tom
should have measured something around 15.6 degrees. The
fact he didn't sends up a very large red flag.

Translation of what Cecil actually is saying:
"Whenever multiple measurements by independent sources disagree with me
the measurements others made must be wrong."

Other multiple measurements by independent sources agree with
me and disagree with you, Tom. Wonder why you neglected to post
this reference from your own server?

http://lists.contesting.com/archives.../msg00540.html

It is a posting to TowerTalk by Jim Lux, W6RMK. I'll just extract
some excerpts.

"For closewound coils, with length to diameter ratios around 5:1, a
series of fairly careful measurements have been made with the coils
arranged vertically above a ground plane, fed at the base, with a
capacitive load on the other end, and the driving frequency arranged
to be at the resonant frequency of the whole assembly."

Sure sounds like your 100 uH 10"x2" coil installed in a mobile ham
radio antenna environment.

"In most cases, the phase shift in the current at top and bottom [of
the coil] was on the order of 10-20 degrees."

Contrary to the assertions of W8JI. Funny, I predicted 16 degrees for
your coil on 4 MHz based on the self-resonant frequency.

"For inductance the signficant thing is that the magnetic field of
one segment pretty much links to the adjacent segments, and less so
for the rest."

Contrary to the assertions of W8JI.

"At this time, the models are sufficiently well developed that they
predict the actual currents and voltages to substantially better than
one percent ..."

As opposed to W8JI's "accuracy".

"The take home message here, regarding loading coils, is that simple
lumped approximations of a loading coil may do just fine for an
initial design cut, but do not adequately reflect reality."

"I think it's best to leave it at: Loading coils are not isolated
lumped elements and cannot be modeled as such."

To which I add: Since a lumped element model is a subset of the
distributed network model, if the lumped element results disagree
with the distributed network results, the lumped element results
are simply invalid.
--
73, Cecil http://www.qsl.net/w5dxp