Path: utzoo!attcan!uunet!tut.cis.ohio-state.edu!ucbvax!hplabs!hpda!hpcupt1!hprnd!pat
From: pat@hprnd.HP.COM (Pat Thaler)
Newsgroups: comp.dcom.lans
Subject: Re: 10BASE2 cable help wanted
Message-ID: <2230021@hprnd.HP.COM>
Date: 11 Aug 89 23:01:34 GMT
References: <442@qtc.UUCP>
Organization: HP Roseville Networks Division
Lines: 31

> Jim Battan writes:
> I'm in the process of converting our thin coax Ethernet from a mixture of
> RG58/U and RG58A/U to something that is within the IEEE spec and
> electrically consistent.  I've heard numerous conflicting opinions about
> what to do, from this newsgroup, computer manufacturers, and coax cable
> makers.  I know I want one of RG58A/U, RG58C/U, or IEEE 802.3 10BASE2
> (aka ThinWire) cable.  I'll be using UTP when we move to our new building
> in eight months (if the 10BASET spec is approved by then), but need some
> new coax now.  This is for a network of 35 Suns, a Sequent, several DEC
> VAXen, and a GatorBox, all talking through a DEMPR and DELNI.
> 
> Are the technical advantages of fully IEEE-compliant cable (e.g. Belden
> 9907) worth the extra cost (cable, new connectors, new crimper)?
> (We're not up against any of the 10BASE2 limits (#nodes, length) yet.)
> 
> Jim Battan     uunet!sequent!qtc!battan    +1 503 626 3081
> Quantitative Technology Corportation (QTC)
> 8700 SW Creekside Place, Suite D  Beaverton, OR  97005
> ----------
When we wrote the 10BASE2 standard, we targeted the media specifications
on RG58A/U and RG58C/U.  I believe that cables which comply with the 
mil specs for RG58A/U and RG58C/U will also comply with the 10BASE2 
specifications.  (I have seen products labelled as RG58A/U or C/U which
did not apear to comply with the mil spec behind the label.)

It has been a while since I worked on coax, but my recollection is that
the difference between RG58A/U and C/U is that one has a foam dielectric.
The foam dielectric is more subject to impedance discontinuities if the
cable is crushed.

Pat Thaler