# Re........ Measuring Coupling Coefficients

From: 	John H. Couture[SMTP:couturejh-at-worldnet.att-dot-net]
Sent: 	Wednesday, December 10, 1997 6:04 PM
To: 	Tesla List
Subject: 	 Re........  Measuring Coupling Coefficients

At 01:57 PM 12/10/97 +0000, you wrote:
>
>From: 	Malcolm Watts[SMTP:MALCOLM-at-directorate.wnp.ac.nz]
>Sent: 	Tuesday, December 09, 1997 10:12 PM
>To: 	Tesla List
>Subject: 	Re........  Measuring Coupling Coefficients
>
>All,
>     I don't know how many times I should post on this one.....
>
>> From:   John H. Couture[SMTP:couturejh-at-worldnet.att-dot-net]
>> Sent:   Tuesday, December 09, 1997 2:01 AM
>> To:     Tesla List
>> Subject:    Re........  Measuring Coupling Coefficients
>>

>>    The K - 1/sqrt(QpQs) is for mutually coupled coils so the K would not be
>> zero.
>>    As Q depends on F it would appear that coupling depends on frequency. I
>> havn't seen an explanation for this contradiction with other K factor
equations.
>>    JHC
>
>...but post I did not two days ago.  k <> kc!!!!!!!!!!!!!!!!!!!!!!!
>
>Call kc anything you like other than k!!!!  It simply describes
>*LOSSES*, not coupling.
>
>Sheesh,
>Malcolm
><snip>

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

Malcolm, All -

Kc equals critical coupling. Coupling is a percentage of flux linkages. At
critical coupling (Kc) the mutual reactance is Xm = sqrt(Rp^2+Rs^2). The
Xm,Rp, and Rs are in ohms, but the Kc is not in ohms and ,therefore, not
"LOSSES". The Kc is still only a percentage of flux linkages.

But if, as you say, the   K = 1/sqrt(QpQs)   only occurs at Kc then
critical coupling is dependent on frequency. In other words K is dependent
on frequency when the coupling is equal to a certain percentage of flux

This leaves the question "What is there about frequency and Q factor that
affects coupling only at a certain percentage of flux linkages?" To me this
means that with a Tesla coil there are lines of magnetic force from the
primary and secondary coils that when a certain percentage of these lines
are linked the frequency is involved. At other percentages the frequency has
no effect.

Now that K can be found without building any coils, does anyone want to
set up a program to find the critical coupling of a series of different TCs
to research the above? The parameters would include K, Lm, Lp, Ls, Q, F, Rp,
Rs, etc. We may find that TC output (sparks) can be increased even more than
what we are doing now.

John Couture