[Prev][Next][Index][Thread]
Re: Recycled: Measuring Coupling Coefficients
From: John H. Couture[SMTP:couturejh-at-worldnet.att-dot-net]
Sent: Thursday, December 04, 1997 2:44 PM
To: Tesla List
Subject: Re: Recycled: Measuring Coupling Coefficients
At 01:40 AM 12/4/97 +0000, you wrote:
>
>From: Malcolm Watts[SMTP:MALCOLM-at-directorate.wnp.ac.nz]
>Sent: Wednesday, December 03, 1997 4:19 PM
>To: Tesla List
>Subject: Re: Recycled: Measuring Coupling Coefficients
>
>Guess I have something to say here:
>
>> From: John H. Couture[SMTP:couturejh-at-worldnet.att-dot-net]
>> Sent: Monday, December 01, 1997 11:27 PM
>> To: Tesla List
>> Subject: Re: Recycled: Measuring Coupling Coefficients
>
><snip>
>
>> fixed coupling and be independent of frequency . However, if the TC
>> capacitor is changed and the operating frequency changed the coupling would
>> also be changed without changing the physical characteristics or geometry of
>> the coil. Has anyone ever checked this?
------------------------------------------------------------
>My experiments suggest k is purely related to coil geometry and
>proximity given that Ls and Lp are *fixed*, not "variables". If you
>alter geometry of either coil or coil proximities to one another, Lp
>and Ls don't change but k does and hence Lm must. It is worth noting
>that unless you know how many turns you will be using on that 15 turn
>primary, you can't pre-calculate k either.
>
>Malcolm
--------------------------------------------------------------
Malcolm -
Your comments prompted me to go back and review the K factor again. I
think you are correct (K related only to geometry) because as I pointed out
in another post the frequencies (F) cancel out in the test equations.
However, this does not happen in the following:
K = 1/sqrt(Qp x Qs) Q = 6.283 F L / R
This situation requires more study. What are your comments ?
Regarding your other comment on "you can't pre-calculate K either" I would
point out that the JHCTES TC computer program will first calculate "how many
turns you will be using on that 15 turn primary" and then will determine the
K factor. In other words the program is doing what you say is necessary to
calculate the K factor.
I think there is much more to the K factor and other TC parameters than
what coilers (myself included) think they know. Unfortunately the Radio and
EE Handbooks do not cover Tesla coils so coilers have to rely on the Tesla
List and the few books specific to TC design and theory
John Couture.