I recall an article in QST or "73", I think the title was,
"For the L of it"
I'm looking for the magazine it was in and the date it was printed.
The article described a series LC, a fixed L and a air variable C.
The impedance of the L was bigger than the impedance of the C,
and by adjusting the C you caused the inductance to vary.
So in effect you have a variable inductor.
Thanks, Mikek