Path: utzoo!attcan!uunet!cs.utexas.edu!mailrus!tut.cis.ohio-state.edu!ucbvax!ucsfcgl!cca.ucsf.edu!jst
From: jst@cca.ucsf.edu (Joe Stong)
Newsgroups: comp.dcom.modems
Subject: Re: Bizarre crosstalk causes crashes
Keywords: low noise cable rec wanted
Message-ID: <2416@ucsfcca.ucsf.edu>
Date: 23 Sep 89 01:27:56 GMT
References: <43@octel.UUCP>
Reply-To: jst@cca.ucsf.edu.UUCP (Joe Stong)
Organization: Computer Center, UCSF
Lines: 8

I have found in the past that some RS-232 ports are just too high impedance;
loading them on the receive side with some resistor in the 1-10K range
will make them less sensitive to noise, and will keep the voltage levels down
(electrostatic coupling).  I tend to run transmit and receive in separate
twisted pairs each with either a ground, or a robust signal that doesn't
change much or respond quickly (like DTR or CD).  I suspect that twisted
pair phone wire would be cheap and effective used this way.  (Beware:
4 wire "quad wire" is not twisted pairs.)