RE: K formula?

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

Original poster: "John H. Couture by way of Terry Fritz <teslalist-at-qwest-dot-net>" <couturejh-at-mgte-dot-com>


Peter -

There are several methods to test for the TC K Factor, however, I know of
only 3 that are useful to coilers.

1. Short the secondary and find frequencies with a grid dip meter (or other
meter) as shown in my TCC Guide.

     K = sqrt(1-(Fo/Fs)^2)

2. Mutual Inductance Test as shown in my TCD Manual.

     K = Lm/(sqrt(LpLs))    Lm = Vs dt/di

3. Two Hump Test

     K  = (F2 - F1)/Fr  approximation
     Fr = F1 + (F2 - Fl)/2

     K  = (F2^2 - F1^2)/(F1^2 + F2^2) (Antonio & Bert)
     Fr = ??

I find it is a good idea to use all three tests. They never give the same
results but are close. The resonant frequency assumes that the primary and
secondary circuits are both tuned to the resonant frequency.

John Couture

--------------------------


-----Original Message-----
From: Tesla list [mailto:tesla-at-pupman-dot-com]
Sent: Tuesday, July 29, 2003 4:21 PM
To: tesla-at-pupman-dot-com
Subject: RE: K formula?


Original poster: "Peter Lawrence by way of Terry Fritz
<teslalist-at-qwest-dot-net>" <Peter.Lawrence-at-Sun.COM>

John,
       I did a google search for, I think, "coupled resonance", and found

K = (Fu^2 - Fl^2) / (Fu^2 + Fl^2)     exact
K = 2 * (Fu - Fl) / (Fu + Fl)         approximate, and very close at low K

I think you've given something equivalent to the "approximate" formula,
but notice how close .1104 and .1107 are.

I'll be writing up something on how I took these measurements soon, I want
the feedback from this group on whether it was a legitimate test or not,
but it's not that easy to describe, perhaps this evening when real work
is more out-of-the-way.

-Pete Lawrence.