jsa00564@uxa.cso.uiuc.edu (03/30/89)
Since there seems to be a lot of traffic dealing with TP solutions, maybe someone has an answer to another TP question (fairly specific). I'm the manager of a medium-sized LAN which uses SynOptics' Lattisnet UTP Ethernet. As everyone agrees, the majority of the problems are cable- based. In my experience, a poor punch, loose clip, etc. can be the difference between connecting and not connecting.... I'm looking for a better way of diagnosing cable flaws in the Twisted Pair environment. I'd just like an instrument that can tell me where the cable problem is. (I know I just described a TDR) I guess that I'm looking for a TDR that is compatible to SynOptics' cabling system. I'd also like to find a relatively inexpensive tool <$5000.. ------------------------------------------------ Jeff Autor jsa00564@uxa.cso.uiuc.edu "Doin' just enough to get by..."
morgan@Jessica.stanford.edu (RL "Bob" Morgan) (04/01/89)
> I'm looking for a better way of diagnosing cable flaws in the Twisted > Pair environment. I'd just like an instrument that can tell me where > the cable problem is. (I know I just described a TDR) I guess that > I'm looking for a TDR that is compatible to SynOptics' cabling system. > I'd also like to find a relatively inexpensive tool <$5000.. The 3Com LanScanner is a handheld TDR that can spot cable flaws in TP or coax Ethernet, and it costs ~$1K. Check it out. - RL "Bob" Morgan Networking Systems Stanford
cball@ishmael (04/04/89)
>/* Written 8:32 pm Mar 31, 1989 by morgan@Jessica.UUCP in ishmael:comp.dcom.lans */ >> I'm looking for a better way of diagnosing cable flaws in the Twisted >> Pair environment. I'd just like an instrument that can tell me where >> the cable problem is. (I know I just described a TDR) I guess that >> I'm looking for a TDR that is compatible to SynOptics' cabling system. >> I'd also like to find a relatively inexpensive tool <$5000.. > >The 3Com LanScanner is a handheld TDR that can spot cable flaws in TP >or coax Ethernet, and it costs ~$1K. Check it out. Our first set of cables was 10% DOA and another 10% died the first time someone bent the cable. Out of desperation, I built a cable tester with two RJ45 modular sockets. One simply loops each pair, the other has two LED's in series with a 1k resistor(so the LED's don't burn out) all hooked into a 9v battery. The loopback socket accepts both RJ45 and RJ11(we share cabling with our phones and use dual RJ11 plates) The LED's readily identify whether the cable is good, dead, or marginal(the LED flickers when the connection is disturbed i.e. "wiggled"). It sure has made a world of difference for us. Our lines go through two punch down blocks and we've found occasional pair reversals, or bad lines. To readily identify these problems I use a short cable segment with one RJ11 end for our wall plates and a 1k, 1.5k, and 3.5k resistor hooked up as follows. -----| cable /---------| PLUG -----------|-- 1k --| -----| |-- 1.5k--| \-- 3.5k--| The resistors are oriented so the readings increase from top to bottom at the wire center blocks. These two "instruments" can be built for ~$10 and some soldering time. While I would still buy an instrument that could tell me if a circuit is ok from the wire center with the transceiver still plugged in, these are perfectly adequate to isolate the source of a problem. Charles Ball Intermetrics, Inc. cball@inmet.inmet.com it