Secondary Rseries and Q measurement

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

Original poster: "Terry Fritz" <teslalist-at-qwest-dot-net>

Hi All,

When I was playing with the pinger and Paul's TCMA program, I became 
interested in how to really measure a secondary coil's RF resistance and 
Q.  I found this great document by Agilent:

http://hot-streamer-dot-com/temp/AgilentImpedanceMeasurementHandbook.pdf

I spews out everything one would ever want to know about Z measurement ;-))

So I started hooking me stuffs up:

http://hot-streamer-dot-com/temp/NewMag/0505-01.jpg

Probably not the most beautiful RF testing rig yet ;-))  Many loose 
ends!!  But it does seem to work very well.  It is based off the idea in 
HP's ("A's") book on page 2-1:

http://hot-streamer-dot-com/temp/NewMag/0505-02.jpg

My system ended up looking like this:

http://hot-streamer-dot-com/temp/NewMag/0505-03.gif

I can easily box it up into a more official thing since it seems pretty cool!

I had to add in the scope probe impedance ((2.75 pF 10M Tek5100 (The BEST 
HF RF probe on Earth!!)) since I did not have a perfect no loss probe 
(actually I do, but I don't trust it "yet").  My circuit looks like this:

http://hot-streamer-dot-com/temp/NewMag/0505-05.gif

Don't be put off by the fancy stuff if you want to try this.  It is all 
pretty basic and should work well with far less than $7000 worth of test 
stuffs.  My Low-Z amp ( 
http://hot-streamer-dot-com/TeslaCoils/Misc/Low-ZAmp/Low-ZAmp.jpg ) is not 
perfect, so the HP 34401a multimeter helped to be sure the signal source 
was at 1Vrms.

Since I had that extra 10Meg resistance of the scope probe in there, I sat 
down and figured out its effects by hand...  Two hours later I gave up and 
let MathCad do it in about 3 seconds :o)))

http://hot-streamer-dot-com/temp/NewMag/0505-04.gif

But the 10Meg probe did not seem to affect things too much as it turned out 
for lower Q's.  The scope pretty much read out the Q directly!

For purists, note that C is calculated as Fo=1/(2 x pi x SQRT(L x C)) 
instead of Fo = SQRT(1/LC-(R/2L)^2)/(2*pi).  That does add some error but 
the equations using the perfect stuff are "bad"...  But the equation for R 
in the MathCad file works pretty good (4%).

So I tested my Magnifier's L2 coil:

169.5 turns
#20 stranded hook up wire
12.24" diameter
12.05" long
6.05mH
Sonotube form

and got this:

kHz	Vout(V)		Q	Rseries(Ohms)

100	290		228	13.2	Rp starts to have an effect here.
150	225		223	19.9
200	161		160	47.6
250	117		116	81.7
300	64		63	178.7

Seems Rseries ~doubles for every 50kHz increase in frequency.

Not sure what it all means, but I think I am doing "something" ;-))

Cheers,

	Terry