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From: boze@cpe.UUCP
Newsgroups: comp.dcom.lans
Subject: Re: RG58 vs. RG58 C/U
Message-ID: <-76592479@cpe>
Date: Wed, 5-Aug-87 15:03:00 EDT
Article-I.D.: cpe.-76592479
Posted: Wed Aug  5 15:03:00 1987
Date-Received: Sat, 22-Aug-87 15:15:07 EDT
References: <4857@columbia.edu>
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Nf-ID: #R:columbia.edu:-485700:cpe:-76592479:000:1409
Nf-From: cpe.UUCP!boze    Aug  5 14:03:00 1987


Can someone explain the difference between RG58 and RG58C/U coax, in particular
as it applies to suitability for use as thinwire ethernet cable?

I'm frequently asked for advice on setting up thinwire ethernets, and while
I've heard that it's a bad idea to use anything but RG58 C/U, I'm always
pressed for an explanation as to why a cheaper or more readily available
substitute can't be used (e.g. "plain" RG58, RG58 A/U, or old RGB cables).

Usually I insist on RG58 C/U, but the asker winds up getting some cheaper cable
to work and giving me a raspberry.  This time the cable is going in my office,
though, so I'd like to do a little more homework; if nobody knows the answer,
a pointer to the document that describes the cable nomenclature would help.
Thanks.
						Chris


The RG58 Cable has an Impedance of 52 to 53 Ohms. The Manufacturers of
Ethernet hardware specify the cable to be used as 50 +/- 4%. Typically
the RG58 cable will exceed this when used in larger/longer networks. On
a small network the RG58 usually will function, but the larger the network
grows the more problem occur. The Network used here worked fine using the RG58
cable until the network was about 250 ft long. The Network is now at the maximum
length using RG58 A/U or RG58 C/U as specified, with no problem due to the cable.
Also there is a difference in the Capacitance per foot of RG58 Cable versus RG58
A/U or RG58 C/U.