I stand corrected. yes, 600 ohm must be balanced because
it is less than 377 for each line to infinite ground.
However, it is universally shoved through coax.
- Robert -
PS: I still think "voltage" came first. <g>
On Mon, 24 Apr 2006 16:12:37 +0100
John Woodgate <[email protected]> wrote:
> In message <[email protected]>, dated Mon, 24
> Apr 2006, Robert A. Macy <[email protected]> writes
> >symmetrical ==
> >the signal is plus phase in one conductor and zero phase
> in the other with reference to infinite ground.
> >
> >examples:
> > twisted pair
> > twisted pair in shield
> > 300 ohm TV lines
> >
> >unbalanced ==
> >the signal is completely in one conductor [well, tries
> to be completely in one conductor] and is referenced to
> the other conductor, thus with respect to ground one
> conductor is supposed to have 0 signal and the other has
> it all.
> >
> >examples:
> > 50 ohm coax
> > 75 ohm coax
> > unknown coax for 600 ohm audio
>
> Balance is nothing to do with voltages. It's about
> impedances. Yes, it came as a bit of surprise to me, too,
> but that was a long time ago.
>
> And '600 ohm audio' was a balanced connection system, not
> coaxial. 600 ohm coax would be a very strange thing. The
> formula is Z = 138*log(D/d) where D and d are the outer
> and inner conductor diameters. So D = 22275d, and if d =
> 0.1 mm, D = 2.2275 metres.
> --
> OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and
> www.isce.org.uk
> 2006 is YMMVI- Your mileage may vary immensely.
>
> John Woodgate, J M Woodgate and Associates, Rayleigh,
> Essex UK
>
>
-
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