Re: Recycled: Measuring Coupling Coefficients

From: 	John H. Couture[SMTP:couturejh-at-worldnet.att-dot-net]
Sent: 	Thursday, December 04, 1997 6:50 PM
To: 	Tesla List
Subject: 	Re: Recycled: Measuring Coupling Coefficients

At 01:23 PM 12/4/97 +0000, you wrote:
>From: 	Edward V. Phillips[SMTP:ed-at-alumni.caltech.edu]
>Sent: 	Wednesday, December 03, 1997 1:27 PM
>To: 	tesla-at-pupman-dot-com
>Subject: 	Re: Recycled: Measuring Coupling Coefficients
>"Refer to Terman's
>Radio Engineers' Handbook. For example, in radio circuits the K factor
>varies with the frequency because of the variable  tuning capacitor.
>Changing this capacitor changes the operating frequency and changes the
>coupling. "
>	Refer to Terman a bit more carefully.  The coupling factor
>for an inductor is simply M/sqrt(Lp*Ls), no matter what the circuit.
>If there is  coupling through both mutual capacitance AND mutual
>inductance (not at all the case for Tesla coils) then the effective
>coupling factor DOES change with the value of the tuning capacitors.

  Ed -

  I agree the coupling (K) factor is  M/sqrt(Lp*Ls)  and there are others.
Isn't there some mutual capacitance between the self capacitances of the
coils especially Tesla coils with large coil type primaries ? The Medhurst
equation gives relatively large self capacities for D/L ratios of less than one.

  How about "if the TC cap 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 ?".

  What are your comments on the equation

   K = 1/sqrt(Qp x Qs)     and    Q = 6.283 F L / R

  where the frequencies (F) do not cancel out as they do for the other test

  The more you dig the diggier it gets.  (: <)

  John Couture