RE: [TCML] Interesting pages on Q factors

[Jim Lux <jimlux@xxxxxxxxxxxxx>]

-----Original Message-----
>From: Jim Mora <wavetuner@xxxxxxxxx>
>Sent: Aug 25, 2008 8:04 PM
>To: 'Tesla Coil Mailing List' <tesla@xxxxxxxxxx>
>Subject: RE: [TCML] Interesting pages on Q factors
>
>Hello Friends,
>
>Who else has done coil analysis of high Q coils?.  My 8" coil which was
>wound with 22 Awg 200 degree insulation and coated with oil based Poly. A 4
>to one ratio, the secondary's Q was somewhat disappointing where the degree
>15 turns was very high and was coupled to a .03Uf cap. Of course throw
>enough power at it and it does very well.



10 years or so ago, our esteemed former moderator, Terry, did a bunch of tests on the Q of a fairly large secondary, over a number of days, looking for changes in properties with temperature and humidity.  Maybe searching the archives might turn it up, if you use the right search terms.  

FWIW, the Q of a coil with 1000 turns of AWG 22 at 100kHz, is going to be dominated by the AC resistance of the wire, and less so the coil form.  

Consider a 12" diameter coil 60" long at 20 TPI.. about 1200 turns, roughly 3600 ft of wire.  The DC resistance of the wire is about 60 ohms.  The reactance of the 75 mH inductor at 100 kHz is about 50K ohms.. so the Q is around 1000.
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