[TCML] High Primary Q

["Barton B. Anderson" <bartb@xxxxxxxxxxxxxxxx>]

Hi All,

How high does the primary Q have to be? Reason I ask is I don't think 
it's as high as assumed and I include myself in that initial assumption.

I was looking at Rac and Rdc in primary's this weekend and came across 
an interesting find. Rac is amazingly high in the primary and culminates 
into a rather low Q. How low? How's the 50 to 100 range sound excluding 
proximity effects.

For example, 8.5 turn primary with 1/4" tubing. Length = 789.1cm, 
thickness is .254cm, and equivalent height if shaped into a ribbon is 
1.995cm (using ribbon strip calculations).

Rdc = p*length/cross sectional area
p is resistivity in ohm per cm = 0.000001678
Rdc = 0.000001678*789.1/(.254*1.995) = 2.61 mOhms

Rac = length*sqrt((p*pi*u*f)/ht)
p = resistivity in ohm per cm = 0.000001678
u = relative permeability of annealed copper = 0.000001256629
f = frequency = 229106

Rac = 789.1/sqrt((0.000001678*3.14*0.000001256629*229106)/1.995) = 688.3 
mOhms

Q = sqrt(L/C)/Rt = sqrt(0.000025669/0.0000000188)/(.00261+.6883) = 53.5!

I am only looking at a significant portion of impedance but haven't 
included surge impedance which in my particular coils case is 37.3 ohms.

So, where is the high Q? I can't find it.

Take care,
Bart


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