Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Posting-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!henry
From: henry@utzoo.UUCP (Henry Spencer)
Newsgroups: comp.dcom.lans
Subject: Ethernet noise problem?
Message-ID: <7823@utzoo.UUCP>
Date: Tue, 24-Mar-87 19:07:23 EST
Article-I.D.: utzoo.7823
Posted: Tue Mar 24 19:07:23 1987
Date-Received: Tue, 24-Mar-87 19:07:23 EST
Organization: U of Toronto Zoology
Lines: 23

I'm just in the process of activating some long-dormant PDP11 Ethernet
hardware, and have hit a problem.  The hardware is an Interlan NI1010A
controller with an Interlan NT100 transceiver and a vampire tap.  (Yes,
I know this isn't the latest and greatest...)  The controller seems to
check out properly, but it claims it is unable to send because of excess
collisions.  It is the only thing on the Ethernet, which is a 27 m (I
think) chunk of the yellow cable, factory-fresh, terminators on both ends,
DC impedance correct as measured on the tap.  The Carrier Sense and
Collision Presence LEDs are on solid (although this is not indicative of
duty cycle because there are pulse stretchers on them) when the transceiver
is connected up, and off when I unplug the transceiver cable at the
transceiver.  To me this says "bad transceiver", "bad tap", "bad cable",
or "major noise problem".  Noise should not be excessive; the environment
isn't exactly electrically quiet -- a lot of pre-FCC equipment -- but no
arc welders either.  The DC impedance being correct suggests to me that
the tap and cable are not grossly defective.  I'm really hoping this isn't
a bum transceiver, it's a bad time for that.  Any suggestions?

Oh, the transceiver and controller were bought in the same order and appear
to be theoretically compatible as nearly as I can tell.
-- 
"We must choose: the stars or	Henry Spencer @ U of Toronto Zoology
the dust.  Which shall it be?"	{allegra,ihnp4,decvax,pyramid}!utzoo!henry