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

Consider me silly as well as an "old wife". A choke balun has common
mode impedance, and that impedance is its single most important quality.
If the common mode impedance isn't adequate, it won't perform its
function. It can be measured by short circuiting the input conductors
together and output conductors together to temporarily make one
conductor, and measuring the impedance between the ends.

. . .

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.

I agree that saturation isn't a problem, but disagree about the reason.
Core flux density is a function of the common mode current, which is in
the same direction in the wires and doesn't cancel out. The objective of
the balun is to minimize this current, but in a high power system even
with an effective balun, the I^2 * R loss, where I is the common mode
current, can still get large enough to make the core hot. However, if
you use a high-permeability, low frequency ferrite, the flux density
will still be way below saturation even when the core is hot enough to
break.

. . .

Roy Lewallen, W7EL