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From: julian@bongo.uucp (Julian Macassey)
Newsgroups: comp.dcom.telecom
Subject: Re: New Double-jack Wall Plates, Crosstalk?
Message-ID: <8500@accuvax.nwu.edu>
Date: 31 May 90 15:47:03 GMT
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In article <8435@accuvax.nwu.edu>, peter@ficc.ferranti.com 
(Peter da Silva) writes:

> We just had new phone service hooked up, two lines: one for data, the
> other for voice. Instead of designating one jack for data and hooking
> up the rest for voice, my wife let them install a new kind of
> wallplate with two lines at each point ...

	There is a certain amount of dejavu here: Quad wire in phone
installations causes crosstalk. The jacks that were installed will not
be the cause of the crosstalk. So you can't blame the Mrs. for this
one. Crummy wire could be a cause of crosstalk. You say that you have
Red, Green and Black, Yellow wire. This stuff is called quad wire. It
is not twisted pair wire. If you use quad wire you will get crosstalk
between the two pairs. The right wire to use is "Twisted pair". This
stuff has the following color code: White/Blue, Blue/White.
White/Orange, Orange/White. White/Green, Green/White. As a general
rule, the minimum number of pairs in twisted pair cable is three. Yes
there is two pair around, it is rare but I saw some yesterday at
Pacific Palisades - Surf was lousy though.

	The jacks are not the source of the crosstalk. I do this sort
of thing all the time. In about an hour I am going to an establishment
that has telephone and Appletalk sharing the same cable and coming out
to duplex jacks. It works because it is twisted pair.

	So, if you have twisted pair, no worries. If you have quad -
yuck.  But the quad may work.


Julian Macassey, n6are  julian@bongo.info.com  ucla-an!denwa!bongo!julian
N6ARE@K6IYK (Packet Radio) n6are.ampr.org [44.16.0.81] voice (213) 653-4495