A choke balun has NO impedance or turns ratio. It is silly to refer to
one.

To make one just wind 15 or more turns of twin speaker wire on a 2"
diameter, one-hole, ferrite core.

A one-hole core is a ring with a hole in the middle.

Ferrite permeability need not be high. 200 or 300 is good enough and
will provide enough inductance to cover the 160m band. Low
permeability materials also have lower loss at the higher frequencies.
Not that a choke balun is a lossy component. Efficiency is extremely
high.

Because the length of wire is only about 1/8th of a wavelength at 30
MHz it will be ok at that frequency too.

All the talk about saturation is so much hot air. You couldn't
saturate it even if you tried. The currents in the two wires run in
opposite directions and cancel each other out.

It has a a lower loss and higher power-handling ability than a core
wound with the usual very small diameter coax.
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Reg.