Current through coils
 

Reg Edwards wrote:

I thought there is/was a restriction that "Everything" must include

"a

significant portion of a wavelength".


===================================

There are no problems. A very short coil behaves as a very short
transmission line.
----
Reg.



C'mon Reg! We both know that a 1/4 inch diameter loop is NOT a
transmission line at 0.1 MHz. :-0

Current through coils
 

Tom Donaly wrote:
I'm glad to know that I can substitute a coil of wire every time I
need a transmission line. So tell me, Reg, what
are the specs on the coil I'd need to make a transmission line
transformer to match 75 ohms to 325.33 ohms?

How about at least tell Reg the frequency?
--
73, Cecil http://www.qsl.net/w5dxp

Current through coils
 

Tom Donaly wrote:
What about figure 2, Cecil?

Figure 2 suggests that any coil with a delay over 15 degrees
should be analyzed by discarding the lumped circuit model
and instead using the distributed network model. Every coil
I have talked about on this thread has a delay greater than
15 degrees. 15 degrees of impedance transformation will transform
50 ohms into 54+j120 ohms with a difference in SWRs of 7 to one.
Does that really sound like a reasonable reason for keeping the
lumped-circuit model?

Roy just said in another posting that the reflection model
will solve all the problems that the lumped circuit model
will solve. It just gets clumsy as far as the math goes.

It is interesting to watch the gurus retreat into fantasy
where they were only ever talking about tiny point inductances
to start with. Anyone who has been following this argument
over the years knows otherwise.
--
73, Cecil http://www.qsl.net/w5dxp

Current through coils
 

Cecil Moore wrote:
Tom Donaly wrote:

I'm glad to know that I can substitute a coil of wire every time I
need a transmission line. So tell me, Reg, what
are the specs on the coil I'd need to make a transmission line
transformer to match 75 ohms to 325.33 ohms?


How about at least tell Reg the frequency?

Reg is old enough to pick his own frequency.
73,
Tom Donaly, KA6RUH

Current through coils
 

I'm glad to know that I can substitute a coil of wire every time I
need a transmission line. So tell me, Reg, what
are the specs on the coil I'd need to make a transmission line
transformer to match 75 ohms to 325.33 ohms?
73,
Tom Donaly, KA6RUH
=======================================
Every coil is a transmission line.

But not every transmission line is a coil.
----
Reg.

Current through coils
 

Cecil Moore wrote:

Tom Donaly wrote:

What about figure 2, Cecil?


Figure 2 suggests that any coil with a delay over 15 degrees
should be analyzed by discarding the lumped circuit model
and instead using the distributed network model. Every coil
I have talked about on this thread has a delay greater than
15 degrees. 15 degrees of impedance transformation will transform
50 ohms into 54+j120 ohms with a difference in SWRs of 7 to one.
Does that really sound like a reasonable reason for keeping the
lumped-circuit model?

Roy just said in another posting that the reflection model
will solve all the problems that the lumped circuit model
will solve. It just gets clumsy as far as the math goes.

It is interesting to watch the gurus retreat into fantasy
where they were only ever talking about tiny point inductances
to start with. Anyone who has been following this argument
over the years knows otherwise.

Figure 2 shows that the authors considered their model to be
that of a shorted stub to replace the inductance of their Tesla
coil. They didn't say that a coil of wire is a shorted stub,
only that it performs the same function as one in the calculations.
You're waffling and trying to slick your way out of an embarrassing
situation again, Cecil. O.k., I'll accept the shorted stub
substitution. Heck, I'll even accept a solution involving
op-amps, (provided you don't use it in transmit mode). What I won't
accept is pretending a long hank of transmission line with a load
at one end performs the same impedance transformation in the same way
as a coil of wire.
73,
Tom Donaly, KA6RUH

Current through coils
 

Roy Lewallen wrote:

Reg is correct. Even a very short structure, much shorter than a
wavelength, acts like a transmission line. A short structure just acts
like a short transmission line. It's just that if it's short, there are
simpler ways to analyze it which will get us essentially the same
answer. But we can use full blown transmission line analysis on any
structure if we choose, and should get the correct answer.

Roy Lewallen, W7EL

Dave wrote:

EVERYTHING????

I thought there is/was a restriction that "Everything" must include "a
significant portion of a wavelength".

:-)

Reg Edwards wrote:

EVERYTHING has Inductance, Capacitance and Resistance, and therefore
behaves as a transmission line.
----
Reg, G4FGQ




If we do, we're going to have our work cut out for us. When the
fundamental quantities L, R, C, and G are unknown functions instead
of constants, analysis gets tricky. If it didn't get tricky, we could
solve for currents on conductors with simple equations instead of
having to use moment methods to numerically solve intractible
integral equations.
73,
Tom Donaly, KA6RUH

Current through coils
 

Tom Donaly wrote:
You're waffling and trying to slick your way out of an embarrassing
situation again, Cecil.

I sincerely do not know what you are babbling about. I'm
not aware that I am in an embarrassing situation and if
I were aware, I would ask someone to enlighten me. I have
read Dr. Corum's articles multiple times and understand
more and more each time I read them. I am using the scientific
method to correct my mistakes and move on. What are you doing?
Mounting ad hominem waffling and slicking attacks.
--
73, Cecil http://www.qsl.net/w5dxp

Current through coils
 

Tom Donaly wrote:
Cecil Moore wrote:

Roy just said in another posting that the reflection model
will solve all the problems that the lumped circuit model
will solve. It just gets clumsy as far as the math goes.
. . .

I said "transmission line" model, not "reflection" model. I want to
clarify this because I don't want what I said to be interpreted as an
endorsement of Cecil's alternate theories involving traveling waves.
Implicit in what I said is also that the transmission line model or
equations must be used correctly.

Roy Lewallen, W7EL

Current through coils
 

Roy Lewallen wrote:

Cecil Moore wrote:
Roy just said in another posting that the reflection model
will solve all the problems that the lumped circuit model
will solve. It just gets clumsy as far as the math goes.

I said "transmission line" model, not "reflection" model. I want to
clarify this because I don't want what I said to be interpreted as an
endorsement of Cecil's alternate theories involving traveling waves.
Implicit in what I said is also that the transmission line model or
equations must be used correctly.

What's the difference between the transmission line model and
the reflection model?
--
73, Cecil http://www.qsl.net/w5dxp