John Popelish wrote:

Cecil Moore wrote:
Increasing the length of a coil or transmission line doesn't
change its velocity factor at a fixed frequency.

That is an interesting hypothesis.

Since I know you are going to nit-pick that statement, I
probably should add "appreciably" in front of "change". :-)

How would you go about testing its validity?

The velocity factor of a piece of transmission line doesn't
change appreciably with length. The velocity factor of a
straight wire doesn't change appreciably with length.

I would think that a two wavelength coil would be approximately
twice as long as a one wavelength coil which would be
approximately twice as long as a 1/2 wavelength coil.

The equation for the velocity factor of a coil depends upon:
1. The diameter of the coil
2. The number of turns per unit length
3. The frequency

None of those factors are dependent upon the length of the
coil.

(Have you heard of end effects?)

Of course, it's the 5% difference between 468/f and
492/f. I'm not talking super accuracy here - just better
accuracy than anyone has yet measured.

It is akin to your suggestion that a coil be installed
between two current nodes and its number of degrees
calculated from that. I will try to take that same
coil that I have been talking about and use your
suggestion to see how close the results are.

However, I am preparing for a 6 state Harley road trip over
the Easter holidays and will not be back until Monday.
--
73, Cecil http://www.qsl.net/w5dxp