[Boatanchors] Drake preselector construction?

[Ian Wilson]

I'm interested to know how the Drake 2B preselector is able to
tune 3.5 - 30MHz. From the schematic, it consists of two
similar LC sections. Each section has a 234pF variable capacitor
and a ganged variable inductor.

To cover the 8.6:1 frequency range requires the square root of the LC
product to be also 8.6:1 also. Let's say 9:1 to allow for production
tolerances.

A 234pF variable capacitor will have a minimum capacitance of
say 5pF, with tube and stray capacitances bringing that to a total
of perhaps 15pF. This is a capacitance range of say 16:1.

An inductance range of (9 x 9) / 16 will be required to realize the
LC product needed. This comes to slightly more than 5:1.

So .. what did Drake use to implement a small variable inductor with
a 5:1 inductance range?

Also, this has to be something that can be driven from a common
shaft with the pair of capacitors. Or is there some mechanical linkage?
The preselector box is fairly small if I recall correctly (not near the set
at the moment).

73, ian K3IMW