Hi Mikek,
Attached is representative Q-Curve for constant diameter, 6", and
inductance, 240uH, at varying tpi values.
As tpi decreases, turn count increases, wire resistance increases, Q
decreases.
Wire loss, Q=X/Rs, is a function of f/sqrt(f) Q increase as frequency
increases.
Core loss, parallel resistance, and possibly Q meter parallel
resistance, is Q=Rp/X. Q decreases as frequency increases. Assuming Rp
is a constant.
John KN5L
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On 9/24/22 12:04 PM, Mikek wrote:
On Sat, Sep 24, 2022 at 04:54 AM, John KN5L wrote:
Attached is a representative Q Curve for a 240uH inductor.
Blue trace is XL/Rs series resistance wire loss Q
I don't get why Q is going up, losses generally increase faster that XL
does, and Q is always lower above about 1MHz than below, (contrawound
coils are slight exception)
Skin effect and core loss increase with frequency and maybe proximity
effect, I'm not sure about that.
Green Trace is Rp/XL parallel resistance core loss Q
Clueless
Red trace is wire and core combined Q
Ya, I don't get that, losses should increase with frequency, both wire
and core.
Black XL trace is added for XL math check.
Well, I get that one!
In above, core loss is a constant Rp. Based on your plot, core Rp
increases with frequency.
But I don't have a core, it's an air inductor, wound on a 6" polystyrene
pipe coupler.
Feedback?
????????????????????????????????? Mikek
