Richard Harrison wrote:

...
Terman says on the "Mechanism of Operation of the Traveling-Wave Tube"
at the bottom of page 678:
"The applied signal propagates around the helix and produces an electric
field at the center of the helix that is directed along the helix axis.
...
Best regards, Richard Harrison, KB5WZI


And, obeys basic rules, such as:

http://www.allaboutcircuits.com/vol_2/chpt_1/6.html

So, a summary of your point? Afraid I am a bit dense here today ...

Regards,
JS

John Smith wrote:
"So, a summary of your point?"

The velocity of the wave traveling on the turns of a coil is slightly
less than 300 million meters per second. Divide the number of meters of
wire in your coil by 300,000,000 and you get the number of seconds
required for the signal to get from one end to the other on the coil,
almost. Actual delay is slightly more because material surroundings slow
the wave a little more than a vacuum does. There is no magic
instantaneous transfer of energy from one turn to another within a coil.
If there were, Terman would have told us so.

Best regards, Richard Harrison, KB5WZI

Richard Harrison wrote:
... There is no magic
instantaneous transfer of energy from one turn to another within a coil.
If there were, Terman would have told us so.

Best regards, Richard Harrison, KB5WZI


Richard:

Thanks, got you now, and of course, no disagreement here. However, if
anyone has a view to the contrary, I would be interested in the
specifics ...

However, there is something akin "special case" which does come to my
mind: Say a two turn coils' configuration was changed to two single
turns ... somehow, even if insignificant, this same interaction of what
is occurring in one turns must be "felt" by the two turn coil. (crud, I
hope you can "decode" that ...)

What say you?

Regards,
JS

John Smith wrote:
However, if
anyone has a view to the contrary, I would be interested in the
specifics ...

In a coil wound on an iron-core toroid, do you believe
the flux follows the wire in the coil and ignores the
iron in the toroid?

Coupling is, of course, not nearly that good in an air-
core coil but coupling exists nonetheless. Some of
the current generated in a coil is through the air-core
transformer action between coils.
--
73, Cecil http://www.w5dxp.com

Cecil Moore wrote:
John Smith wrote:
[said, "gray areas exist!]

In a coil wound on an iron-core toroid, do you believe
the flux follows the wire in the coil and ignores the
iron in the toroid?


At designed freqs, permeability of core material, turns
size/spacing--the core OVERWHELMS all other forms of magnetic
coupling--I cannot even begin to think how I would measure EM coupling
between turns in such an environment ...

Coupling is, of course, not nearly that good in an air-
core coil but coupling exists nonetheless. Some of
the current generated in a coil is through the air-core
transformer action between coils.

Air core, EM coupling between turns exists, in what degree--I simply
cannot, probably, afford the equipment to measure ...

As I stated, for at least the most part, we are in agreement ... it
seems only logical ... however, things are not always as they seem (now,
how's that for "wiggle room?" ;-) )

Regards,
JS

Richard Harrison wrote:
There is no magic
instantaneous transfer of energy from one turn to another within a coil.

It's not magic and it cannot occur at faster than light
speed. Magnetic coupling between air-core coils does
exist. It is just not of the magical magnitude asserted
by W8JI.

You wouldn't use the same argument on an iron-core
coil, would you, where virtually all of the coil#1
flux does indeed link with coil#N?
--
73, Cecil http://www.w5dxp.com