I like John P's suggestion of a form with radial spokes, like a wagon
wheel or like petals of a flat flower. You can make one from wood,
with a wooden disk in the middle, drilled to accept dowels (round
pieces of wood).

This type of coil was/is popular with crystal-radio and other AM-radio
buffs... it's called a "spider web" coil. Use an odd number of
spokes/petals, so that alternate turns on the wire spiral go onto
opposite sides of any given petal.

I gather that one attraction to this winding style is that it results
in a very low amount of parasitic capacitance, and thus a high Q.

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
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