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Richard Clark wrote:

If he could put it to music, it might top the charts over Cat Stevens'
"Time in a Bottle."

I think Jim Croce did that one. Cat Stevens did Wild World, Peace
Train, Moon Shadow, etc. And to top the charts these days you pretty
much have to be a rapper and have a dance crew.

ac6xg

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Cecil Moore wrote:
John KD5YI wrote:
"Cecil Moore" wrote in message
A 75m Texas Bugcatcher loading coil certainly
qualifies as a distributed load being about
1/8WL long.

A 75m Texas Bugcatcher loading coil is about 30 feet long?

*Electrically*, yes. Its velocity factor calculates
out to be about 0.02 at 4 MHz and it is physically
0.563 feet long. 0.563'/0.02 = ~28 feet.

At 4 MHz, a 75m Texas Bugcatcher coil replaces ~28 feet
of wire in the antenna. That is ~41 degrees at 4 MHz.
(Note there is about 44 feet of wire in a 75m Texas
Bugcatcher loading coil.)

Equation 32 in the following IEEE paper is what I used
to calculate the velocity factor of the loading coil.

http://www.ttr.com/TELSIKS2001-MASTER-1.pdf

How well does your answer compare with the curves in Fig. 1 given the
number of turns in a Bugcatcher coil?

ac6xg

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Jim Kelley wrote:
How well does your answer compare with the curves in Fig. 1 given the
number of turns in a Bugcatcher coil?

Since the curves are generated from the equation,
they should match perfectly. As a matter of fact,
I have a dot on that graph at 0.004 and 5k. The
VF is ~0.02.
--
73, Cecil, IEEE, OOTC, http://www.w5dxp.com

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"Art Unwin" wrote in message
...
On May 4, 3:22 pm, Cecil Moore wrote:
HMMmm
The big bang started with energy being supplied to mass at zero
temperature

so now you are a cosmologist and can perfectly explain the start of the big
bang... have you discussed this with stephen hawking recently?

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"John KD5YI" wrote in message
...

You appear to be trying to make lumped components into distributed
components to suit your arguments. Shame on you.

its all a question of scale... your lumped inductor looks distributed to me
under a microscope, and still obeys all of maxwell's equations.

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"Art Unwin" wrote in message
...
On May 3, 5:36 pm, "Dave" wrote:

You really enjoy playing the simple person. You don't find the weak
force as believable but do find Coriolis effect believable so I gave
you what you desire, something to believe in.

i don't find the coriolis effect to be believable in causing tilted antennas
either, but its more fun to talk about that than the weak force. i find the
image of watching your antenna spiral down a toilet drain amusing.

The basic level of time in physics is based
on the speed for a capaciter to release all its energy which is then
replaced by a magnetic field.

so now you can define time in terms of time, sounds like another circular
argument to me. it takes time to discharge and that defines time... why
doesn't the time it takes to rotate the earth define time? that is more
sensible and has been known to man for much longer than discharging
capacitors.

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"Cecil Moore" wrote in message
...
John KD5YI wrote:

(snip)

A 75m Texas Bugcatcher coil is an example of the type
of air-core loading coil that I am talking about. It's
about 6" diameter, 4 tpi, and 6.75" long. Dr. Corum's
equations indicate a VF of ~0.02 for such a coil used
on 4 MHz which makes it electrically about 28 degrees
long.

You appear to be trying to make lumped components into distributed
components to suit your arguments. Shame on you.

No, just the opposite. I am trying to keep others
from considering large air-core distributed network
loading coils to be lumped components (which they
obviously are not). Dr. Corum says any coil electrically
longer than 15 degrees (0.04WL) needs to be treated
as a distrubuted network, not as a lumped-circuit.


Wake up, Cecil. The 6.75 inch long Texas Bugcatcher coil falls into the
lumped component category (being only .002WL at 75m).

John

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On May 5, 5:33*pm, "Dave" wrote:
"Art Unwin" wrote in message

...
On May 3, 5:36 pm, "Dave" wrote:

You really enjoy playing the simple person. You don't find the weak
force as believable but do find Coriolis effect believable so I gave
you what you desire, something to believe in.

i don't find the coriolis effect to be believable in causing tilted antennas
either, but its more fun to talk about that than the weak force. *i find the
image of watching your antenna spiral down a toilet drain amusing.

The basic level of time in physics is based
on the speed for a capaciter to release all its energy which is then
replaced by a magnetic field.

so now you can define time in terms of time, sounds like another circular
argument to me. *it takes time to discharge and that defines time... why
doesn't the time it takes to rotate the earth define time? *that is more
sensible and has been known to man for much longer than discharging
capacitors.

Because the magnetic field produced launches the particle which
travels at the speed of light by impact. This is the basic metric of
time. A particle emits light when it's momentum changes. Particles
carry just one color which is a measure of its frequency. There are
only three colors available but together they form the basics of all
colours. Colors emitted can be seen in the Northern lights as the
momentum changes of particles entering the Earth's medium where they
come to rest as unbound electrons on diamagnetic surfaces.
Hawkins is in hospital at the moment so you can't chat with him

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John KD5YI wrote:
Wake up, Cecil. The 6.75 inch long Texas Bugcatcher coil falls into the
lumped component category (being only .002WL at 75m).

Sorry John, we are not talking about *physical* length
- we are talking about *electrical* length which, like
a piece of coax, depends upon the velocity factor. The
velocity factor for a Texas Bugcatcher coil is ~0.02.

6.75"/0.02=337.5", 337.5"/12 = 28 feet,
28'/(246'/lamda) = 0.114 WL

Thus a 75m Texas Bugcatcher loading coil is electrically
about 41 degrees long at 4 MHz. Hint: It is a slow-wave
structure described in "Fields and Waves ..." by
Ramo, Whinnery, and Van Duzer, 3rd edition, page 476.

The equation for the approximate velocity factor for
an RF coil meeting the specified physical conditions
is given in equation 32 on page 4 of:

http://www.ttr.com/TELSIKS2001-MASTER-1.pdf

Fig. 1 gives the VF for various diameter/wavelength
ratios and turns/wavelength. Here's how to determine
the VF from the Fig. 1 graph.

For the coil in question, calculate the
diameter/wavelength ratio and plot it on the x axis.

The diameter/wavelength ratio for the Texas Bugcatcher
is ~0.5/246 = 0.002, i.e. 2x10^-3 on the graph.

For the coil in question, calculate the
turns/wavelength ratio and select the proper curve.

The turns/wavelength ratio for the Texas Bugcatcher
is 4tpi*12*246' = 11,800, i.e. slightly to the left
of the left-most 10k curve.

That puts the Texas Bugcatcher squarely in the slow-
wave category with a velocity factor of ~0.02.
--
73, Cecil, IEEE, OOTC, http://www.w5dxp.com

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Art Unwin wrote:
Particles
carry just one color which is a measure of its frequency.

This is true for orbital electrons but not true for
free electrons as exist in conductors like copper
and aluminum. Free electrons can emit photons of any
frequency. We change the transmitting frequency of
the photons by adjusting our VFOs to virtually
limitless frequencies.
--
73, Cecil, IEEE, OOTC, http://www.w5dxp.com