Tom Donaly wrote:
Tell me a couple of things, Cecil: 1. the diameter of your bugcatcher
coil, and 2. the turn to turn wire spacing. I'd like to use the
information, using the formulae in your reference, to see just how
long your bugcatcher coil is electrically.

Please note that when my 75m bugcatcher coil is mounted
just above my GMC pickup ground plane, it is electrically
almost four times longer than it is laying on a stack of
books in my hamshack. The coil capacitance to ground is
obviously a lot higher when mounted over a ground plane.
The ground plane reduces the VF to approximately 1/4
the value obtained in isolation.

1. The measured self-resonant frequency of the coil
mounted on my pickup is ~6.6 MHz.

2. The measured self-resonant frequency of the coil
on a mag mount on my all-metal desk is ~6.6 MHz.

3. The measured self-resonant frequency of the coil
isolated from any ground is ~24.5 MHz.

The self-resonant frequency needs to be measured in
the environment in which it is installed. That means
one needs to model the coil 3 inches above a perfect
ground plane before calculating the self-resonant
frequency, Z0, or VF. I doubt that Dr. Corum's equations
take that into account since it would seem self defeating
to operate a Tesla coil over a physically close ground
plane. But I could be wrong on that point.

The coil data is: ~6" dia, ~6.7" long, 26.5 T, seems
very close to 4 TPI. Looks to be #14 solid wire.
--
73, Cecil http://www.qsl.net/w5dxp