From: fmsys!macy@usenet.INS.CWRU.Edu (Macy Hallock)
Newsgroups: comp.dcom.telecom
Subject: Re: House Wiring Question
Date: 29 Jul 92 04:41:00 GMT
Organization: The Matrix
X-Submissions-To: telecom@eecs.nwu.edu
X-Administrivia-To: telecom-request@eecs.nwu.edu
X-Telecom-Digest: Volume 12, Issue 591, Message 5 of 10

Concerning the 10BaseT EMI emmission in residential applications
discussion that has been going on for a while:

Although 10BaseT was intended for use on Unshielded Twisted Pair (UTP)
with fairly uniform impedance characteristics, it can be, and is used
with Shielded Twisted Pair (STP) successfully.

AT&T makes a decent STP cable for use with their Premises Distribution
System.  Its intended for RS-232 and can be used for Token Ring, too.
Others make a similar cable, including Belden and Columbia.  I have
not taken the time to carefully compare and match published
specifications.  AT&T's cable people told me that 10BaseT over STP is
not uncommon.

I have also run 10BaseT over STP that was originally for RS-422 use.
Never thought it would work, but it works just fine.  Ahh ... but we
cheated:

Bear in mind that I test the cable with a Microtest scanner prior to
installation in order to confirm its ability to operate
satisfactorily.  In most cases, I have observed reliable operation of
many type of STP at distances of 70 to 100 feet.  If the cable does
not have a good uniform twist in the pairs, then it fails every time.
As does "quad" type (red-green-yellow-black) JK non-paired old style
station cable.

This attests to the robust functionality of the signalling format and
today's 10BaseT equipment.  I'm very partial to using STP or UTP over
RG-58 coax.  (But then again, I'm a 20 year veteran telecom engineer,
what do you expect?)

Note that the silver satin base cords (telephone type) used with
10BaseT Network Interface cards all to often to connect with the wall
jack are not sheilded or twisted pair.  They radiate and attenuate
like heck, too.  Use a twisted pair type base cord if you can.
Non-UTP base cords will run 10BaseT 14 to 25 feet, FYI.  UTP base
cords have nearly the same characteristics of Level 3 (good qualty)
UTP voice station wire, which will do 300 feet plus.

Good UTP base cords are made by Homaco and Orrtronics, among others.
Also: very few people know that EIA-468 compliant jacks and
wiring/color code practice needs to be observed.

If you need a catalog, Homaco has a nice catalog with 10BaseT stuff in
it (they are in Chicago, and most telecom supply houses carry their
stuff) AT&T, Orrtronics, Krone, Nevada-Western, Hubbell, Leviton,
Suttle, Seimon and others all have good catalogs and suitable
products, too.

I use Homaco, Orrtronics, Hubbell and Leviton here.  AT&T, too, but
its a little more pricey.  Why do I use these brands?  I like the
products, they are carried by several of the suppliers I deal with and
they seem to be priced competively.  Also, no one has been willing to
offer me a large bribe to change brands...  [grin].

I'd put in STP in a residence without hesitation.  I'd also test the
cable first. Either a Homaco patch panel or AT&T 110 type patch blocks
would be in the wiring area.  Perhaps termination of the 10BaseT cable
directly in crimp-on RJ-45 plugs (to allow them to plug directly into
the 10BaseT hub) would work, but I tend to associate that practice
with "cheap and dirty" work, something I see all too often.  Seems as
though computer stores do not know how to install cable neatly ... I
have to fix a lot of their installations.
 
This advice is worth exactly what you paid for it ... be careful and
you will be rewarded with a working installation, but you must do the
homework.


Macy M Hallock Jr N8OBG 216.725.4764 macy@fmsystm.uucp
macy@fmsystm.ncoast.org [No disclaimer, but I have no real idea what
I'm saying or why I'm telling you]