On Jan 27, 9:42*pm, K7JEB wrote:
On Jan 20, 5:47 pm, Gary wrote:

*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.
I recall the article and have it around somewhere. *The problem with
this (if you want to call it a problem) is it only works for a small
range of frequencies.

They do the reverse of this in AM broadcast antenna matching
networks (doghouses) where the object is NOT to have a variable
capacitor. *A fixed, high-reactance capacitor is placed in series
with a 'tappable' inductor and the capacitor is 'tuned' by adjusting
the tap on the inductor. *Again, works well at one frequency,
but not over an octave bandwidth.... K7JEB

The OP's arrangement works well for impedance matching and is suitable
for tuning a circuit to resonance. I dont believe the circuit he
described would be much different from the resonant circuit in a
Colpitts osc.

Jimmie