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Re: k - Alternative Method



Hi Malcolm,

	Terrribly sorry for not corresponding lately. I've been in rush to 
finish my thesis since I might be in line for a job at Bell Lab's new wafer 
fab. I've been a bit more active on the list lately, however, since I've 
been home the last 5 dayes with the flu!

	Anyway I just saw your post - amazing - I was just thinking about 
the exact same method! Doing a quick and dirty error anaylsis suggests that 
one needs perhaps 4digits for k of about .1, though 3 1/2 digits might 
suffice for the higher k values. I have also noticed that handheld LCR 
meters tend to be thrown off in the L values if the winding resistance is 
above a few ohms....


	The plus sign in your M=(Lx+Ly)/4 formula bugs me though. If I may:

Ls = Secondary Inductance
Lp = Primary Inductance

then 

Lx = Lp + Ls +2M
Ly = Lp + Ls -2M

So

M=(Lx-Ly)/4

I hope I haven't goofed (if so I'll blame the flue ;). In the limiting case 
of no coupling Lx=Ly=(Lp+Ls) and this gives M=0.

Take care,

-Ed