Loading Coils; was : Vincent antenna
 

Gene Fuller wrote:
A proper "quote" does not include any extra analysis.

Yet another diversion devoid of any technical content.

You will not find "4.5 degrees" in quotes anywhere
in my article indicating that I did NOT quote W8JI.

W8JI did not say "4.5 degrees", you did.

There are 17 different definitions of "say" in my
Webster's. Two of those definitions are used in the
following sentence.

When W8JI *said* "3 ns", he *said* a mouthful, indicating
that there is a 4.5 degree delay through the test coil.
--
73, Cecil http://www.w5dxp.com

Loading Coils; was : Vincent antenna
 

AI4QJ wrote:
62.5nsec delay. It is correct. Measurement would easily prove it. Maybe on
monday when I go to the lab I will make such a coil and put it on a scope,
take a picture and prove it. However, my peers would be wondering why I was
trying to prove such a thing; it's sort of like proving gravity exists is it
not? What would be the point?

Sort of like not having to measure the delay in order to know
it is impossible for it to be 3 ns.

So it cannot be 2-4nsec.

My point exactly. The erroneous measurement was made using
current devoid of any phase shift.
--
73, Cecil http://www.w5dxp.com

Loading Coils; was : Vincent antenna
 

Gene Fuller wrote:
As far as I can tell, W8JI did not do any math or other type of analysis
to come up with the 3 ns delay. There was some surrounding discussion,
but the delay itself was simply read from an instrument.
So let me repeat my earlier questions.

I previously answered your question in capital letters.

What went wrong? Why is that number incorrect?

This is about the 20th time that I have explained the error
that W8JI made. The signal he used to measure phase shift
didn't possess a phase shift. W7EL made the same mistake in
his "delay through a loading coil" measurements. When the
phase of the total current changes hardly at all from one
end of a 1/2WL dipole to the other, that current CANNOT even
be used to measure the delay through the wire. Why do you,
W8JI, and W7EL think a current with an essentially unchanging
phase can be used to measure phase shift? This is all explained
on my web page.
--
73, Cecil http://www.w5dxp.com

Loading Coils; was : Vincent antenna
 

On Dec 2, 7:46 am, "Jimmie D" wrote:


When you shorten an antenna dont you(shouldnt you) have to replace the C
along with the L?

Jimmie

Well, if you have less C, you would need more L. Depends where
you shorten the whip. Below or above the coil..
Shortening the whip below the coil does not effect the tuning near
as much as shortening the stinger above the coil.
IE: take my 11 ft mobile whip tuned to 80m. I can add a 3 ft
extension to the base, and it will shift the tuning a fairly small
amount in the band.. But add 3 ft to the stinger, and the shift
will be quite large.. You will be way out of the ham band.
Of course, if you have a choice, it's always better to add more
C, than it is to add more L.
I'm not sure if this is exactly what you are asking...
MK

Loading Coils; was : Vincent antenna
 

On Sun, 2 Dec 2007 09:59:24 +0000, Ian White GM3SEK
wrote:

(This
also means that measurements made on a coil in isolation will have very
limited relevance to the behaviour of the coil as part of a complete
antenna.)

Hi Ian,

Your parenthetical is EXACTLY what devastates the logic of forcing the
real inductor to observe a constant angular length according to
Cecil's misapplication of the so-called Corum rule. It also reveals
the problem with Tom's measurement. However, negating Tom does not
validate Cecil - and vice versa.

As for the implicit (or explicit) expectation of Kirchhoff being
satisfied, that is a lose-lose proposition from the get-go as these
discussions violate the necessary zero scale of wavelength, something
you also covered quite well:
The main difference is that the real-life
coil occupies a significant fraction of the total physical height of the
antenna.

73's
Richard Clark, KB7QHC

Loading Coils; was : Vincent antenna
 

On Sun, 2 Dec 2007 00:46:54 -0800 (PST), wrote:

You actually need more wire than the equal 1/4 wave whip.
Say a monopole at 3.8 mhz is 61.57 ft tall.
The appx 9.84 ft whip base loaded needs 63.35 ft of wire.
The center load needs 88.32 ft of wire.
The 2/3 load needs 103.97 ft of wire.

Hi Mark,

You have proven through a very simple logic that Cecil's fixed angular
specification for a coil (a la the prostitution of Corum) fails
utterly. OTHERWISE, one coil would have satisfied all placements
along the length of the short monopole!

A very, very simple solution that absolutely rolls over these
narcissistic exercises in creating spreadsheets of proofs.

73's
Richard Clark, KB7QHC

Loading Coils; was : Vincent antenna
 

On Sun, 2 Dec 2007 14:24:42 -0500, "Jimmie D"
wrote:

If the delay in the coil Cecil has talked about is measured without the
appropriate C and R would not this affect the normal parameters of the coil.
The delay through a delayline or a loading coil is dependent on more than
just L.

Hi Jimmie,

The Corum math is available. Can you find the delay contribution of
externalities to the coil in those equations?

73's
Richard Clark, KB7QHC

Loading Coils; was : Vincent antenna
 

Richard Harrison wrote:
Surely the signal follows the path of the turns on a coil.

Not entirely as adjacent turns do have an effect on
each other so there is a grain of truth in what W8JI
is saying. W8JI's error was in taking that grain of
truth and rationalizing that small grain into an
explanation that is off by at least a magnitude.

It looks like a reasonable rule of thumb is that the
velocity factor of a coil is approximately half what
it would be if the signal followed the wire entirely.
In other words, if one calculates the delay in the
length of wire used to wind the coil, the actual
delay through the coil is likely to be half of that
value.
--
73, Cecil http://www.w5dxp.com

Loading Coils; was : Vincent antenna
 

Owen Duffy wrote:
I say that the phase relation MUST be the same everywhere on the coil.

That does not seem to me to support Cecil's proposition at all, I
understand Cecil to argue that there is a substantial phase change in the
coil current along the coil.

Please understand exactly what I am saying, Owen.

1. There is a *substantial* phase change in the *traveling-wave*
current along the coil. Traveling-wave current is hard to
measure in a standing-wave antenna but its phase yields
complete and accurate phase/delay information.

2. There is virtually *no* phase change in the *standing-wave*
current along the coil. Standing-wave current is easy to
measure in a standing-wave antenna but its phase yields
close to *zero phase/delay information*.

3. In a standing-wave antenna, the total current is primarily
standing-wave current. In a loaded mobile antenna, the standing-
wave current is approximately 90% of the total current thus
tending to mask the traveling-wave current.

W8JI's and W7EL's "measurements" were made using standing-
wave current. They should have instead used traveling-wave
current. It's an easy mistake to make but one would think,
after five years, it is time to admit the mistake.
--
73, Cecil http://www.w5dxp.com

Loading Coils; was : Vincent antenna
 

Tom Donaly wrote:
That is when it is electrically
close to 90 degrees in length.

In length? You still don't get it.

Yes, in electrical length, not physical length. You still
just don't get it.

I gave an example of a stub that is 45 degrees in
physical length yet 90 degrees in electrical length.
You really should take time to verify that stub.
--
73, Cecil http://www.w5dxp.com