Re: More Coupling...

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Ed Phillips by way of Terry Fritz <twftesla-at-uswest-dot-net>" <evp-at-pacbell-dot-net>

Tesla list wrote:
> 
> Original poster: "Barton B. Anderson by way of Terry Fritz
<twftesla-at-uswest-dot-net>" <tesla123-at-pacbell-dot-net>
> 
> Hi Ed,
> 
> Measured K on my flat primary for my 12.75" x 45" coil.
> The flat primary is 16.5"ID, 0.375"wire, 0.625" spacing (c-c) (or 0.375
> edge to edge), and 11.6
> turns in the case of using my 0.06uF cap setup.
> 
> I used a method of measuring I believe Terry posted a couple years ago.
> 
> Measured current of primary using a hair dryer in series (10.95A). Then
> measured secondary
> voltage (secondary + 1uF cap + 18k ohm in series) at 2.59V.
> 
> Mutual Inductance M = V / (377 * I) or 2.59V / (377 * 10.95A) = 627.4 M
> 

	That's a perfectly valid and exact method.


> K = M / sqrt(Lp * Ls) = 627 / (107.13uH * 87.6mH) = 0.205 K
> 

	Surprised it's that high.  Will have to try a similar measurement here
using a small flat primary I happen to have.


> Anyway, that's K on that day. I am only aware of one program that calc'd K
> but it was
> preliminary and I haven't heard anything about it in a "long" time.
> Measuring is pretty easy and
> can be done with a simple DMM.
> 
> Bart

Ed