The secondary and primary are resonant with each other.

The self-capacitance of the secondary is all that is required.
(Compare with early Xtal sets that had an FGL, but
no tuning capacitor (or condenser for those days) in evidence.

"Paul Burridge" wrote in message
...
Anyone know what differentiates a Tesla coil from any other old coil?
Is it simply that they all seem to be EHT types or is there some
particular quirk concerning the way they're wound? IOW, what sets 'em
apart?