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Re: Coil form material - Q-killer?

Original poster: Jim Lux <jimlux@xxxxxxxxxxxxx>

At 03:02 PM 1/8/2007, Tesla list wrote:
Original poster: "Gav D" <gdingley@xxxxxxxxx>

Hi all,
I have been reading the Medhurst paper from which the much used coil
self-capacity formula originates and noticed a formula for dielectric
loss. Using this formula and calculating skin-effects, I have found
that the PVC pipe often used for winding a secondary contributes more
to reducing Q-factor than the conductor itself; I am correct?

PVC isn't all that lossy at a few hundred kHz. There is a loading effect from the dielectric, but that just increases the parasitic C, lowering the self resonant frequency. I would imagine that resistive losses still dominate.

I would appreciate your comments,