[comp.periphs.scsi] <23638@cbnewsj.att.com>

neese@adaptx1.UUCP (03/05/91)

>/* ---------- "SCSI cables -- any recommendations?" ---------- */
>Nowadays, 'every' catalog offers SCSI cables.  Is there any
>concensus as to better/worse manufactuers/vendors [national
>level -- not local, please!]?
>
>I seem to recall a couple of postings or magazine articles over
>the past year[s?] suggesting that there have been refinements in
>the cable specifications.  I absolutely HATE to waste time with
>problems that turn out to have been avoidable with better
>connectors, cables, etc... so I'm interested if I/we could
>benefit from others experience.  Particularly interesting -- and
>probably unobtainable -- would be any true engineering study
>results.
>
>So mundane... but soooo important[?]....

Mundane is an understatment.  How about boring?  But very important.  I
have looked at a quite a few cables and manufacturers over the years and
have found that Amphenol Interconnect (Endicot, NY) makes the best and
most consistent cables around.  This is where I get my round external
cables.  They have the standard external SCSI-1 connector and the new SCSI-2
connector.  And it is the round cable that could give you the most headaches.
You have no way of knowing the construction of the cable, short of cutting it
open or asking the manufacturer.  Some won't give out that information.  It
could be twisted pair, but how are the pairs routed?  Is there a solid core?
Are the wires bundled in the middle? Of course if you are looking at the
standard flat ribbon (50 wire) cable,  as long as it is 100 ohm impedance,
it's hard to go wrong.  The connectors for this cable is the place you
can get bit big time.  Some of these connectors are only rated up to 12
insertions (single wipe).  Everybody, including Amp, makes these cheap
connectors.  Also a consideration is the material of the connector.  All
of our adapters use gold plating for the internal pin header.  So you should
also use gold contact connectors to get the best electrical characteristics.
If you use tin, you will eventually have problems as electrolysis does it
number.

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