Toni wrote:
Thanks four your answers.

I was forgetting you normally use coax in a unbalanced configuration
where the braid is supposed to be at 0 voltage so only currents matter.

How do you define "0 voltage"? Do a groups.google.com search of this
newsgroup and you'll find quite a bit of discussion about the futility
of trying to define a voltage between two distant points in the presence
of a field.

Would all this still hold if you used the coax as a _balanced_
transmission line? (unusual but -I think- possible). In this case
wouldn't voltages develop on the braid that could capacitively couple to
other conductors?

(assuming perfect solid shield, ...)

A coax line is balanced when the common mode current is zero. It's
unbalanced when common mode current exists. See
http://eznec.com/Amateur/Articles/Baluns.pdf for more information.

Voltages don't couple, fields do.

There was also some discussion not too long ago on this group about the
role of current in generating both electric and magnetic fields.

Roy Lewallen, W7EL