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Original poster: "Malcolm Watts" <m.j.watts@xxxxxxxxxxxx>

Hi Ed,

On 29 Mar 2005, at 19:52, Tesla list wrote:

> Original poster: Ed Phillips <evp@xxxxxxxxxxx>
> " > A questions for the old timers...Who first introduced the use of
>   > Medhurst C into Tesla coil calculations, and when?
> I independently discovered it and its usefulness. It is on record in a
> 1995 publication. I have since had reason to believe that at least one
> other person (unknown to me) had attempted to introduce it before I
> did. At the time I joined this forum, it was not widely (if ever)
> mentioned and I pushed it for all it was worth.
> Malcolm"
>  One of the first things I did when I first got my original TRS-80
> (1978) was to write a simple QuickBasic program for calculation of the
> LF inductance and SRF of unloaded coils, using Wheeler's
> approximations for inductance and a lookup table interpolation of
> "Medhurst" data from the fourth edition of the Radiotron Designer's
> Handbook.  At the same time I wrote a mutual inductance program based
> on the methods in Circular 74, with the specific purpose of
> calculating coupling in TC's. Later on I moved them over to my Mac SE
> and turned them into compiled basic, then back into compiled basic on
> a PC.  I suspect other guys used the procedure earlier but never
> bothered to write about it.
> Ed

Agreed. I too was using it back in the 80's but never publicly
mentioned it until the mid-90's. I also got it from the Radiotron
Designer's Handbook (great publication!). So why were wirelength
equations so popular when I joined the list in '95? None of them
worked for the general case and everyone who had one swore by it.
The one person I remember from about that time who came up with one
that did get close was Ed Harris (I wonder where he is now?).