On Sun, 11 Jan 2009 19:31:33 -0000, "Richard Ferryman"
wrote:

I have never seen a clear explanation as to why they are twisted.
Does it improve the balance? Does it affect the coupling? Is it better to
twist or not to twist - that is the question.
Dick G4BBH

Hi Dick,

Twisting is to bring the two wires into very close proximity. This
reduces the characteristic Z of the transmission line they form. The
reason for wanting to have a low characteristic Z is related to the
impedance transformation (this Z being the geometric mean of the
source Z and load Z). This is generally an issue with one of those Zs
being very low and then you may want to use flat (almost foil) wires
(all wires being insulated, of course).

73's
Richard Clark, KB7QHC