wrote:
The coil does NOT have to occupy tens of degrees nor does it have to
provide any current phase delay from end to end.
The coil has to obey the laws of physics. Most real-world
75m loading coils occupy tens of degrees of the mobile
antenna. Your assertion that nearly 100% of the coils link
nearly 100% of the total flux is unrealistic. The effect
of coil flux linkage approximately doubles the VF from
e.g. ~0.02 to ~0.04, not from 0.02 to near 1.0, as you
assert. A speed up by a factor of 2 is a lot more
realistic than a speed up by a factor of 50.
The phase delay and current taper is tied to the load impedance on the
open end of the coil and the construction of the coil, not to the
electrical degrees.
Reference my stub example which contains *NO COIL*. There
is a *short circuit* looking into the stub.
---30 deg 450 ohm line---+---11 deg 50 ohm line---open
The 450 ohm line provides 30 deg of phase shift. The
impedance discontinuity at '+' provides 49 deg of
phase shift. The 50 ohm line provides 11 deg of phase
shift. All this happens without any coil in sight.
A very similar thing happens with a 75m mobile antenna.
The base loading coil provides tens of degrees of phase
shift. The impedance discontinuity between the coil and
the stinger provides tens of degrees of phase shift. The
stinger provides tens of degrees of phase shift.
You seem to have taken the tens of degrees of phase shift
in the coil and transferred those number of degrees to
the impedance discontinuity. That is a mistake based on
the presuppositions of the lumped circuit model.
Asserting such is akin to asserting that there is no delay
in the 450 ohm line section in the stub above.
My opinion is Lewallen and maybe a dozen others have a good handle on
how it works. It appears you have gradually came more to center also,
but I'm not quite positive how far. At least you no longer appear to
be saying the coil represents missing electrical degrees.
For months I have been saying that the mobile antenna doesn't
have to be 90 degrees long. It has been a couple of years
since I said that the coil represents missing electrical
degrees. You know that but still attempt through inuendo to
make hay from a mistake I made two years ago. I correct my
mistakes in real time. It doesn't matter what I said two
years ago. And you object when someone does that to you.
For months I have been saying that the coil delay is what it
is and nobody has made a valid measurement of that delay. The
best information available on that subject (to the best of
my knowledge) is Dr. Corum's paper at:
http://www.ttr.com/TELSIKS2001-MASTER-1.pdf
I'd bet money I can build a coil that has very low phase delay. I'd
also bet I could build one with larger phase delay **at the same point
and frequency in the same system**.
We are not discussing how smart or tricky you can be in producing
one special case coil. We are discussing real-world 75m bugcatcher
coils. Whatever you assert has to apply to all coils, not one
special case. It doesn't matter that you can create one coil
that matches your assertions about all coils. That's like asserting
that all cars are white and producing one white car as proof.
W5DXP wrote:
The 3 nS delay measured by you and the undetectable delay
measured by W7EL were invalid measurements of delay.
So you say. We have only your opinion or view on that, and that
disagrees with other people's opinions. You are not the final word.
It's my view based on all the facts. If I'm wrong, I will freely
admit it and correct my misconceptions. However, at the present
time, I think I have proven that standing wave current on a
standing wave antenna cannot be used to measure the delay through
a wire, much less through a coil. You and W7EL both used standing
wave current, with its unchanging phase, in your phase measurements.
W7EL says that EZNEC agrees with me on that point. So he is in
the position of either disagreeing with EZNEC or admitting that
his phase measurements though accurate were meaningless. EZNEC
proves that standing wave current phase cannot be used to measure
phase shift through a wire, much less through a coil. As recently
as last month, you appeared not to know that fact as illustrated
by this previous posting.
************************************************** ******************
Cecil Moore wrote:
I made self-resonance measurements on loading coils
and standing wave current measurements on a 6m dipole.
W8JI said my measurements were in error. W7EL said
my measurements agreed with EZNEC.
Replying to my measurements, here are your words and W7EL's words:
W8JI wrote on 3-16-06:
Your measurements are probably wrong. ... After we resolve the
error in current, we can move on.
W7EL replied on 3-16-06:
The measurement looks good to me. The phase is exactly what EZNEC
predicts -- constant along the wire.
************************************************** ***************
W7EL agrees that the phase is "constant along the wire". How can
a signal with constant phase be used to measure phase shift through
a wire? or through a coil? After a year, there is still no answer
provided for this technical question. The answer provided by
EZNEC is at:
http://www.qsl.net/w5dxp/travstnd.GIF
Standing wave current suffers zero delay all along a 1/2WL
dipole whether it be in a wire or in a coil. The delay through a
typical mobile loading coil on 4 MHz appears to be about 25 nS
about half of what one would get in a straight wire equal to the
wire used in the coil.
Again it depends on the form factor of the coil. By altering the coil
with no other changes it can be made to vary quite a bit.
We are talking about 75m bugcatcher coils, Tom, not one special
case coil engineered by you. If your assertions fail for a 75m
bugcatcher coil, then they fail in reality. You assertions have
to be valid for all cases or else they are invalid. Finding one
special case that agrees with your assertions, e.g. your previous
toroidal coil measurement, may boost your ego but doesn't really
matter one iota in the overall scheme of technical fact.
--
73, Cecil
http://www.qsl.net/w5dxp