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- Newsgroups: sci.electronics
- Path: sparky!uunet!munnari.oz.au!metro!sunb!macadam!johnh
- From: johnh@macadam.mq.edu.au (John Haddy)
- Subject: Re: Coax Question
- Message-ID: <1992Jul27.221257.6368@mailhost.ocs.mq.edu.au>
- Sender: johnh@macadam (John Haddy)
- Nntp-Posting-Host: macadam.mpce.mq.edu.au
- Organization: Macquarie University, School of Mathematics, Physics, Computing and Electronics
- References: <1992Jul20.140143.19341@yang.earlham.edu> <1992Jul22.052519.901@athena.cs.uga.edu> <1992Jul27.125000.9458@cs.hw.ac.uk>
- Date: Mon, 27 Jul 1992 22:12:57 GMT
- Lines: 42
-
- In article <1992Jul27.125000.9458@cs.hw.ac.uk>, adrian@cs.hw.ac.uk (Adrian Hurt) writes:
- |> In article <1992Jul22.052519.901@athena.cs.uga.edu> mcovingt@athena.cs.uga.edu (Michael A. Covington) writes:
- |> >In article <1992Jul20.140143.19341@yang.earlham.edu> jeremiah@yang.earlham.edu (Jeremiah Wilton) writes:
- |> >>I am wondering what kind of coax is used in Ethernet thin and thick wire
- |> >>connections. I am unconvinced that some really expensive special stuff
- |> >>is necessary. Might not RG-58 or 59 work for thinwire? How about
- |> >>composite video cable (the thin cheap stuff)?
- |> >
- |> >Thinwire Ethernet is RG-58 (52-ohm).
- |>
- |> According to my catalogues, there are:
- |> Uniradio M43: 50 ohms, one solid 0.9mm central conductor, braid screen.
- |> RG-58C/U: 50 ohms, 19x0.18mm stranded central conductor, braid screen;
- |> RG-58B/U: 50 ohms, one solid 0.8mm central conductor, braid screen;
- |> Thin Ethernet: 50 ohms, 19x0.2mm stranded central conductor, braid and
- |> foil screen (foil round the insulator, braid round the foil);
- |>
-
- Although its not the recommended coax, I can vouch for RG58C/U - our network here
- has over a kilometre of it installed for our Ether network. It's also a damn
- sight cheaper than fully spec.'d Ethernet thinwire coax.
-
- RG59 is no good - its characteristic impedance of 75ohms doesn't fit the
- requirement for a nominal 50ohm coax.
-
- Thick Ether coax could probably be replaced with other cable of similar
- characteristic impedance and _attenuation_ (this is what's important here). The
- last time I looked, however, thick Ether was cheaper than other comparable
- coaxes. This is probably due to quantity in use - miles of RG58 is used for
- purposes other than networks, while the use of low-loss coax of the calibre of
- thick Ether is much smaller.
-
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- Email: johnh@mpce.mq.edu.au, Ph: +61 2 805 8959, Fax: +61 2 805 8983
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