Re: Spaced Coil measurements.

To: tesla-at-PUPMAN-dot-com
Subject: Re: Spaced Coil measurements.
From: "Malcolm Watts" <malcolm.watts-at-wnp.ac.nz> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)
Date: Thu, 10 Jun 1999 23:40:56 -0600
Approved: twftesla-at-uswest-dot-net
Delivered-To: fixup-tesla-at-pupman-dot-com-at-fixme

Hi Ed,
      I just ran your mutual inductance program to calculate the 
inductance of the 10 turn coil. The answer is a lot closer but still 
a bit too low (about 5%). Thanks for pointing out the correction.

<snip>
>     Withe the appropriate "current sheet" corrections for such coils the
> answers are wildly inaccurate.  See any handbook such as the "Radiotron
> Designer's Handbook" for the correction terms.  In my 1941 edition they
> are on page 142. 
> 
>     By the way, Malcom, one of the QuickBasic inductance programs I sent
> you several years ago does include the current sheet corrections.
> 
> Ed

The really telling point about the measurements is that the wirelength 
is starting to approach the 1/4 wavelength at resonance. If I kept on 
reducing the turns, I'd eventually I'd end up with a piece of 
straight wire which no-one could dispute was a poor resonator and a 
good radiator at resonance. Also I was amazed at how well Medhurst 
worked for this coil. While measurements of various kinds seem to be 
reinforcing the lumped view of high Q open resonators, nothing of 
real substance seems to have surfaced in countless measurements to 
support the 1/4 wave view. I will pursue these msmts to the death and 
send all details to the list when I get access to a suitable venue. 

Regards,
Malcolm