Well, if he does cover 207-225 w/ a fixed 10nF in parallel with
whatever tuning cap he has, that implies Cmax/Cmin = (225/207)^2 =
1.18/1. Since Cmin is at least 10nF, the variable to accomplish that
must be 1800pF, at least. That in itself is a pretty good size
variable cap.

Then the implication would be that L = 50uH, and 1800pF would tune that
to 530kHz. The minimum capacitance including stray and effecitve coil
shunt would be 175pF to tune to 1700kHz.

I think he means to buy some fixed caps in the range 1-50nF, not a
1-50nF variable. (Though in this forum, maybe he does mean the
variable!) The fixed caps could make some sense. Maybe put them on
dual stackable banana plugs, and plug together whatever value is
desired.

Switcher, you can do the calcs yourself: 2*pi*freq = 1/sqrt(L*C) --
or use something like the RF calculator that's in RFSim99. And you may
find it's better to not try to cover too wide a range with one loop by
adjusting only the capacitance, for performance reasons in addition to
the fact that the tuning range will get very small as you go to larger
fixed capacitances.

Cheers,
Tom