On Jan 20, 3:32*pm, "amdx" wrote:
* 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

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.

For instance, at 10 MHZ a series 1.6uH L and 318 pF C looks like a .
8uH inductor (good). But at 5.76 MHZ the combination looks like 30
ohm Xc capacitor. At 7.0 MHZ it looks like a short because of series
resonance.

I would not want to replace the roller inductor on my 80-10 antenna
tuner with this, but there are other applications (single frequency)
where it should work just fine.

Gary N4AST