Re: OK to use TV coax for microphone?

"Don Pearce"  wrote...
> As I said in my first reply, if I was forced to use coax for a
> microphone, domestic TV grade would be a very poor choice because in
> general it has perhaps no more than 10% screening (just enough in fact
> to give the cable a stable characteristic impedance, but no more).

That may be the case over there (although I doubt it).
Over on our side of the earth, RF cables, and especially
those intended for television use are 100% ****elded.
Because if they are not, it starts causing problems.
Problems for the cable operators when RF leaks (in
either direction) between the TV station on channel X
and the over-the-air signal of the same station on the
same frequency.  This is a chronic problem in some of
the poorer-maintained systems.

And problems for individuals even with just a run of
several meters to a rooftoop antenna because of the
increased susceptability to RFI, particularly in remote
regions where the signal is weak to start with.

RF coax made for cable TV use have foil ****elds plus
a few strands of wire braid around the foil.  In fact many
of them even have a double foil ****eld.

Don't mistake the wire braid (which may, indeed be only
10% coverage) for the actual outer ****eld of the coax
which is the active ****tion.

> Microphone signals are too small to mess around this way.
> Decent audio grade cable has screening approaching 100%.

And out in remote rural areas, RF signals are of the same
order.