On Mon, 03 Dec 2007 22:08:42 GMT, Gene Fuller
wrote:

Go ahead, try any configuration you want. See if you agree with that web
calculator.

C'mon Gene,

Drop the shoe. What is the result? I've lost track of the URL and
would like to hear the punchline. Cecil won't understand it anyway,
so what difference would it make?

73's
Richard Clark, KB7QHC

Richard Clark wrote:
On Mon, 03 Dec 2007 22:08:42 GMT, Gene Fuller
wrote:

Go ahead, try any configuration you want. See if you agree with that web
calculator.

C'mon Gene,

Drop the shoe. What is the result? I've lost track of the URL and
would like to hear the punchline. Cecil won't understand it anyway,
so what difference would it make?

73's
Richard Clark, KB7QHC

The calculator is at

http://hamwaves.com/antennas/inductance.html

I believe that Owen first mentioned that website, but I could be wrong.

I am looking at the calculation for beta, the axial propagation factor.
It appears to be unchanged for any length of coil from very short to
much longer than a quarter-wave resonant length. I cannot change the
frequency any more, since Cecil thinks that is a diversion. However, the
calculator does not seem to respond correctly in that case either.

The calculator notes state that it uses the "n=0 sheath helix waveguide
mode", which is what Corum's Telsiks paper was all about. In that paper
he indicated various conditions for validity, such as the fact that the
coil must be near a quarter wave resonance for some of the mathematical
approximations to be valid.

I am not arguing with the "n=0 sheath helix waveguide mode". I am merely
pointing out that the calculator web page seems to be a "one size fits
all" situation that may not be appropriate when required conditions that
are not met.

73,
Gene
W4SZ

Gene Fuller wrote:
In that paper
he indicated various conditions for validity, such as the fact that the
coil must be near a quarter wave resonance for some of the mathematical
approximations to be valid.

What he *didn't* say is that if that same coil is cut
in half and used at the same frequency, the Z0 and VF
change.
--
73, Cecil http://www.w5dxp.com

On Tue, 04 Dec 2007 02:16:36 GMT, Gene Fuller
wrote:

The calculator is at

http://hamwaves.com/antennas/inductance.html

I believe that Owen first mentioned that website, but I could be wrong.

I am looking at the calculation for beta, the axial propagation factor.
It appears to be unchanged for any length of coil from very short to
much longer than a quarter-wave resonant length.

Hi Gene,

On visiting the site, I plugged in Tom's numbers, specifically:
D = 50mm
N = 100
l = 254mm
d = 1mm

ß varied by frequency in a non-linear fashion, roughly x10 per decade
shift up in frequency from 40kHz.

What was strange was how "Parallel stray capacitance" wandered the map
to become inductive (-1 pF) at 40 MHz (and become a non-number above).

73's
Richard Clark, KB7QHC