Path: utzoo!news-server.csri.toronto.edu!cs.utexas.edu!evax!utacfd!merch!cpe!adaptex!adaptx1!neese
From: neese@adaptx1.UUCP
Newsgroups: comp.periphs.scsi
Subject: Re: <13400@unixland.uucp>
Message-ID: <283400065@adaptx1>
Date: 5 Mar 91 09:08:15 GMT
References: <23579@ucunix.san.uc.edu>
Lines: 24
Nf-ID: #R:ucunix.san.uc.edu:23579:adaptx1:283400065:000:1128
Nf-From: adaptx1.UUCP!neese    Mar  4 13:35:00 1991


>/* ---------- "Re: <13400@unixland.uucp>" ---------- */
>In article <283400058@adaptx1> neese@adaptx1.UUCP writes:
>>
>>of the cable.  Myself, I like to use flat cable for the external and build
>>my own.  Garantees impedence matching between the internal and external
>>cables.  The FCC may not like it, but the flat ribbon cable is a good cable
>>as you are garanteed all lines are the same length with alternate signal
>>ground matching.
>
>Shielded ribbon cable is available.  I have also found that simply
>wrapping the cable spirally with a strip of aluminum foil and grounding
>the foil at one end eliminates interference.  This may affect the
>impedance, though.  I have never used this for anything faster than an
>external floppy drive, so I don't know how it would affect a faster
>device.  The convenience of ribbons with clamp-on connectors makes it
>possible for anyone to fabricate a cable at minimum cost and effort.

The problem with shielded cable is the possible induction of noise from
the ground source into the SCSI bus.

			Roy Neese
			Adaptec Senior SCSI Applications Engineer
			UUCP @  neese@adaptex