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Re: Coil form material - Q-killer?

Original poster: Ed Phillips <evp@xxxxxxxxxxx>

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?

I would appreciate your comments,



Not in my experience. I have used both grey and white PVC pipe of various diameters for coil forms and measured their Q up to 30 MHz. No discernible effect on the Q, which is typically several hundred.