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Cecil Moore wrote:
Myths and old wives' tales die hard.

Six years of your bragging about them insures that - like blowing up a
balloon with a slow leak.

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Richard Clark wrote:
Cecil Moore wrote:
Myths and old wives' tales die hard.

Six years of your bragging about them insures that -
like blowing up a balloon with a slow leak.

This is coming from the person who asserted that
reflections from non-reflective glass are brighter
than the surface of the sun.
--
73, Cecil, IEEE, OOTC, http://www.w5dxp.com

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Cecil Moore wrote:
Jim Kelley wrote:
Cecil Moore wrote:
Myths and old wives' tales die hard.

So please stop trying to invent new ones.

I'm not doing that, Jim, just trying to lay the
old ones to rest, e.g. a 3 nS delay through a
10" long 75m bugcatcher loading coil. Please
don't tell me that you believe that a 4 MHz
signal can travel through a large 10" inch
coil in 3 nS - a coil that exhibits a VF of
0.04. That's about seven times the speed of
light.

Given that the speed of light is roughly 3 x10^8 meters per second, and
it would ordinarily take less than a nanosecond to traverse the 10",
it's not *THAT* unbelievable. The delay would depend on the series
inductance and shunt capacitance of the coil. What are those numbers?

ac6xg

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Jim Kelley wrote:
Given that the speed of light is roughly 3 x10^8 meters per second, and
it would ordinarily take less than a nanosecond to traverse the 10",
it's not *THAT* unbelievable.

It is unbelievable for a device with a VF of 0.04
Do you understand how to include VF in a calculation?

The delay would depend on the series
inductance and shunt capacitance of the coil. What are those numbers?

All of those factors are included in the calculator at:

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

Tom's coil is 100 turns, 50.8mm coil diameter, 254mm long,
wire diameter of 1.024mm, and frequency = 4 MHz.

With a wavelength of 75m, exactly how does one obtain a
3 nS delay when the propagation factor is 2.12 radians/meter?
--
73, Cecil, IEEE, OOTC, http://www.w5dxp.com

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Cecil Moore wrote:
Jim Kelley wrote:
Given that the speed of light is roughly 3 x10^8 meters per second,
and it would ordinarily take less than a nanosecond to traverse the
10", it's not *THAT* unbelievable.

It is unbelievable for a device with a VF of 0.04

VF = 0.04 is incredible. I thought you were going to send me the coil
so I could measure it.

ac6xg

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On Wed, 03 Jun 2009 11:59:24 -0700, Jim Kelley
wrote:

It is unbelievable for a device with a VF of 0.04

VF = 0.04 is incredible. I thought you were going to send me the coil

Talk about unbelievable. Given Cecileo's penchant for mystical
selfhood, that would be like asking to borrow the Shroud of Turin.

I eagerly look forward to this turn of events where religious
reliquary moves at a glacial pace through the protocols of interfaith
sanctions.

73's
Richard Clark, KB7QHC

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Jim Kelley wrote:
VF = 0.04 is incredible.

Ignorance makes a lot of things seem incredible.
Not at all incredible according to the Fig. 1
graph that you referenced a few days ago at:

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

Here's how to do it. Draw a horizontal line at
0.04. Where it intersects the lines on the graph
are the real-world coils exhibiting a VF of 0.04.
If you need help drawing that line, send me an
email.

Hint: Those large loading coils are slow-wave
devices described in my Ramo and Whinnery
college textbook from the 1950's. It's on page
410 of the 2nd edition of "Fields and Waves
in Modern Radio", (c)1944, 1953 (the year you
were born). Isn't it about time you read it?

The approximation they use for vp (phase velocity)
is c*sin(pitch-angle)

I thought you were going to send me the coil
so I could measure it.

The coil has been chopped up and used in numerous
projects including my Bugstick article. Don't you
or your students know how to wind a coil? Do you
need step by step winding instructions?
--
73, Cecil, IEEE, OOTC, http://www.w5dxp.com

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Jim Kelley wrote:
VF = 0.04 is incredible.

A little knowledge and logic will make it clear.
My 75m Texas Bugcatcher coil is self resonant
at 8.2 MHz which by definition makes it 90 degrees
long. 90 degrees at 8.2 MHz in free space is 30 feet.

The coil is actually 6.5 inches long, i.e. 0.542 feet.

0.542/30 = 0.018 which is the VF of the Texas
Bugcatcher coil at its self-resonant frequency.

The Texas Bugcatcher coil is 4 tpi. The coil with
the VF = 0.04 is 10 tpi. It all makes sense.
--
73, Cecil, IEEE, OOTC, http://www.w5dxp.com

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Cecil Moore wrote:
Jim Kelley wrote:
VF = 0.04 is incredible.

A little knowledge and logic will make it clear.
My 75m Texas Bugcatcher coil is self resonant
at 8.2 MHz which by definition makes it 90 degrees
long. 90 degrees at 8.2 MHz in free space is 30 feet.

The coil is actually 6.5 inches long, i.e. 0.542 feet.

0.542/30 = 0.018 which is the VF of the Texas
Bugcatcher coil at its self-resonant frequency.

The Texas Bugcatcher coil is 4 tpi. The coil with
the VF = 0.04 is 10 tpi. It all makes sense.

Epicycles made a lot of sense, too. So, about that coil. I'm good in
the call book.

ac6xg

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Jim Kelley wrote:
So, about that coil. I'm good in the call book.

That coil is being used on a bugstick on top of my
pickup. Just wrap 40 turns on a 4 inch diameter piece
of PCV and start alleviating your ignorance.
--
73, Cecil, IEEE, OOTC, http://www.w5dxp.com