Cecil Moore wrote:
Tom Donaly wrote:

If
he applies his reference formulae to one of Tom's coils and it
doesn't show the correct phase shift, though, his theory is in trouble.


His reference formulae are for traveling waves, not standing waves.
We already know that the phase of the standing wave current on a
1/2WL thin-wire dipole varies not one degree over that entire
180 degrees. Yet we know the forward wave undergoes a 90 degree
phase shift from feedpoint to tip and the reflected wave undergoes
a 90 degree phase on the trip back to the feedpoint. Standing wave
phase is virtually unchanging and is therefore useless for trying
to determine the electrical length of a wire or a coil.

Tell me a couple of things, Cecil: 1. the diameter of your bugcatcher
coil, and 2. the turn to turn wire spacing. I'd like to use the
information, using the formulae in your reference, to see just how
long your bugcatcher coil is electrically.
Thanks,
Tom Donaly, KA6RUH

Tom Donaly wrote:
Tell me a couple of things, Cecil: 1. the diameter of your bugcatcher
coil, and 2. the turn to turn wire spacing. I'd like to use the
information, using the formulae in your reference, to see just how
long your bugcatcher coil is electrically.

Please note that when my 75m bugcatcher coil is mounted
just above my GMC pickup ground plane, it is electrically
almost four times longer than it is laying on a stack of
books in my hamshack. The coil capacitance to ground is
obviously a lot higher when mounted over a ground plane.
The ground plane reduces the VF to approximately 1/4
the value obtained in isolation.

1. The measured self-resonant frequency of the coil
mounted on my pickup is ~6.6 MHz.

2. The measured self-resonant frequency of the coil
on a mag mount on my all-metal desk is ~6.6 MHz.

3. The measured self-resonant frequency of the coil
isolated from any ground is ~24.5 MHz.

The self-resonant frequency needs to be measured in
the environment in which it is installed. That means
one needs to model the coil 3 inches above a perfect
ground plane before calculating the self-resonant
frequency, Z0, or VF. I doubt that Dr. Corum's equations
take that into account since it would seem self defeating
to operate a Tesla coil over a physically close ground
plane. But I could be wrong on that point.

The coil data is: ~6" dia, ~6.7" long, 26.5 T, seems
very close to 4 TPI. Looks to be #14 solid wire.
--
73, Cecil http://www.qsl.net/w5dxp

On Wed, 15 Mar 2006 18:03:28 GMT, Cecil Moore wrote:

The coil data is: ~6" dia, ~6.7" long, 26.5 T, seems
very close to 4 TPI. Looks to be #14 solid wire.

Hmmm, dare I plunge into the next, obvious question?

Provide the Velocity Factor and Characteristic Impedance per the
formulas you offered:

Tom Donaly wrote:
What's the formula, Cecil?

http://www.ttr.com/TELSIKS2001-MASTER-1.pdf equation (32)

The velocity factor can also be measured from the self-
resonant frequency at 1/4WL. VF = 0.25(1/f)

I suppose you also
have something that will tell us how to find your coil's characteristic
impedance; o.k., out with it.

http://www.ttr.com/TELSIKS2001-MASTER-1.pdf equation (43)

and we can then achieve closure by comparing the same results with
Reggie's formulas.

Richard Clark wrote:
Provide the Velocity Factor and Characteristic Impedance per the
formulas you offered:

Tom Donaly has graciously volunteered to provide those values.
Please stand by.
--
73, Cecil http://www.qsl.net/w5dxp

On Wed, 15 Mar 2006 20:08:18 GMT, Cecil Moore wrote:

Richard Clark wrote:
Provide the Velocity Factor and Characteristic Impedance per the
formulas you offered:

Tom Donaly has graciously volunteered to provide those values.
Please stand by.

You have nothing to show of your own work employing your own
references?

I can do this myself, as certainly Tom can too; but it says nothing
about your well coming up dry when we ask you to carry your own water
in supporting your claims.

Richard Clark wrote:
.. I can do this myself, as certainly Tom can too; but it says nothing
about your well coming up dry when we ask you to carry your own water
in supporting your claims.

Pure humor with zero technical content follows:
So sue me for being lazy. :-)
--
73, Cecil http://www.qsl.net/w5dxp

On Wed, 15 Mar 2006 20:57:21 GMT, Cecil Moore wrote:
So sue me for being lazy. :-)

The legacy of Xerox research.

Cecil Moore wrote:
Richard Clark wrote:

Provide the Velocity Factor and Characteristic Impedance per the
formulas you offered:


Tom Donaly has graciously volunteered to provide those values.
Please stand by.

Actually, I just wanted to calculate the values for my own personal
edification. You'll have to do the arithmetic yourself, Cecil, and
then it won't mean much, because, as far as I know, no one has ever
done any experimental work to see if these equations have any meaning.
If a coil can slow down an electromagnetic wave as much as these
equations say it can, though, it qualifies as a very interesting device.
73
Tom Donaly, KA6RUH

Tom Donaly wrote:
If a coil can slow down an electromagnetic wave as much as these
equations say it can, though, it qualifies as a very interesting device.

Tom,

Here's another way to think about it.

If an inductor by itself delayed phase as much as Cecil claims, we
could build a phase or time delay system with only a large inductor. As
it is, we must always use a network of capacitors and inductors to
obtain phase delays or a transmission line of any substantial delay.

To construct a delay line, either a small parallel wire line is used or
a spiral around a metal core. The metal core acts like a shorted turn
and reduces flux coupling, and adds distributed capacitance to ground.

73 Tom

On 15 Mar 2006 16:36:51 -0800, wrote:

If an inductor by itself delayed phase as much as Cecil claims, we
could build a phase or time delay system with only a large inductor.

There is another explanation.

A lumped circuit has only one resonance. A transmission line has an
infinite number. It certainly isn't necessary to impose a strict test
of this. Finding second, third, and fourth harmonics for an inductor,
in situ, would certainly be compelling evidence of transmission line
behavior. Otherwise, any delay obtained through pencil whipping the
various formulas (and Reggie's equations veer far from the references
offered) is strictly what occurs AT RESONANCE, and any interpolation
of that delay to other frequencies is a presumption not yet proven.

73's
Richard Clark, KB7QHC