Cecil, W5DXP wrote:
"EZNEC indicates a VF of ~ 0.016."

I calculate about 628 inches of wire in the coil compared with about 10
inches of coil length. It is 62.8 times as far to go around the turns on
the coil as it is to travel through a 10 inch rod. So, velocity factor
is the quotient of 10 divided by 628, or about 0.016. That agrees with
EZNEC.

Best regards, Richard Harrison, KB5WZI

Richard Harrison wrote:
I calculate about 628 inches of wire in the coil compared with about 10
inches of coil length. It is 62.8 times as far to go around the turns on
the coil as it is to travel through a 10 inch rod. So, velocity factor
is the quotient of 10 divided by 628, or about 0.016. That agrees with
EZNEC.

I think we are talking about two different coils. The 6" dia,
6" long, 30 turn Texas Bugcatcher coil is the one with a
VF of 0.016 per EZNEC. The only 10" coil that I remember
being mentioned is w8ji's and EZNEC cannot model that coil.

Dr. Corum's equation yields a VF of 0.0328 for the w8ji coil,
again just about double what the "threaded bolt" approach
indicates.
--
73, Cecil http://www.w5dxp.com

Cecil, K5DXP wrote:
"I think we are talking about two different coils."

Yes, that`s now obvious. I only worked with W8JI`s coil, and your
numbers were for the bugcatcher coil.

I showed my work, so if my method was wrong, my results are probably
wrong too. Someone is likely to point out the error in my ways and I`ll
learn something.

Best regards, Richard Harrison, KB5WZI