To tell you the truth Dick this is the first time I even thought of this...

My first reaction would be to reduce radiation TX and RX like one does
with CAT5 ethernet cable (aka twisted pair). In a transformer though?

You have asked the right group though, there have been heated balun
discussions here before. One of the contributors wrote a PDF article on
it that may be useful... Sorry I dont have the URL on hand..

I'll wait for an answer....

Cheers Bob VK2YQA

Richard Ferryman wrote:
I am in the process of making a 1:1 balun for QRP use and this has made me
think! I have seen many balun designs and construction articles. A fair
proportion of theses advocate twisting the wires before winding on a toroid
core. 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