Sorry to disappoint you John.

Nobody has ever made a significant improvement using aligator clips,
lengths of wire and baluns on a portable whip receiver. Except, if
lucky, merely by chance on one band at the expense of the others.

You may, however, hear a bunch of claims, e.g., by CB-ers and
plagiarising old-wives, based on imagination and wishful thinking.

Signal to noise ratio is what matters. And that's an uncontrollable
function of the incoming signals and noise. the ionosphere, and of the
receiver itself.

However, it's quite interesting to experiment with longer antennas.
Obtain a circuit diagram of the receiver and try to predict what will
happen - if anything.

A most elementary circuit analysis is all that's needed. Otherwise you
will be working entirely in the dark.

Clear your head and forget about a balun. You must have been reading
the wrong magazines articles. You are dealing with an
unbalanced-to-unbalanced, very high impedance-to-high impedance
situation.

Consider a ground conection to the receiver chassis. This lowers the
impedance to more predictable values. OK if you are located
conveniently near to a domestic plumbing system. But even a short rod
in good soil will have some effect for either better or worse.

If you insist, signal to noise ratio MIGHT be improved by using a
single adjustable LC tuned circuit as a pre-selector in conjunction
with a length of wire and a ground connection of some sort. But it
might have an adverse effect.

My guess is that you will end up with a new, Japanese, very expensive,
battery-operated, communications-grade receiver at the end of a
100-feet length of 18-gauge magnet wire. Even if the wire is just
strewn on the ground.

Wait a bit and Chinese, equally good, 1/2-price versions may become
available.

Economics provide the foundations of all engineering. If you don't
understand economics then you don't understand anything. Not even SWR
or the portion of a dipole from which most of the radiation is
supposed to occur.
----
Regards, Reg.