In spite of the fact that I am now using balanced RF feedlines, I am
still trying to understand
"coax" "leakage" modes as some also apply to balanced.

I think most of the noise in coax systems comes from singals that
travel up the outside of
the coax and W1HIS's "Common Mode Chokes" are the best way to deal
with it.
http://www.yccc.org/Articles/W1HIS/
CommonModeChokesW1HIS2006Apr06.pdf

Common mode chokes can also be a big help in reducing noise from
getting to the
antenna via the balanced feed lines.

http://www.repeater-builder.com/ante...rew-shielding-
effectiveness.pdf
Same PDF at Andrews.
http://www.andrew.com/search/docviewer.aspx?docid=737

Terry