Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!seismo!cmcl2!phri!roy From: roy@phri.UUCP (Roy Smith) Newsgroups: comp.periphs,comp.terminals,comp.dcom.lans Subject: Telco-style push down blocks and stranded cable Message-ID: <2551@phri.UUCP> Date: Mon, 5-Jan-87 21:19:50 EST Article-I.D.: phri.2551 Posted: Mon Jan 5 21:19:50 1987 Date-Received: Tue, 6-Jan-87 18:46:53 EST Reply-To: roy@phri.UUCP (Roy Smith) Distribution: world Organization: Public Health Research Inst. (NY, NY) Lines: 42 Xref: mnetor comp.periphs:100 comp.terminals:110 comp.dcom.lans:112 Having finally gotten fed up with the spaghetti in our machine room, I've decided to redo all the terminal wiring using telco-style pushdown blocks. For historical reasons, we've got about 100 lines coming into the machine room for 40 ports -- some are lines run to offices in anticipation of future needs, some are lines no longer in use but which might be needed again some day. What I want to do is set up a panel with a termination for each port on one side and a termination for each external line on the other and patch between them as necessary. Since patching won't be frequent, I don't need anything as fancy as plug-in patch panels; re-doing a punchdown jumper will be easy enough. The problem is that we've got miles of Belden 8723 (stranded shielded twisted pair) all through the building and I understand that punchdown blocks are made to only work with solid wire. Has anybody tried using stranded wire in punch-down blocks? Will it work? The last thing I want is to have hundreds of connections start to work themselves loose in a year or two. We wire our runs like this: 1 ----------------------------------- N/C Computer 2 ----------------------------------- 3 Terminal End 3 ----------------------------------- 2 End 7 =================================== 7 The frame ground is connected to the shield only at the computer end and xmit and rcv are each twisted with a signal ground (we run 9600 over 250+ feet, and one 19.2k line over about 100 feet with no problems, so I must be doing something right). If the 20-30 feet between the patch panel and the computer is 8723, as is the external line, will I loose much if I make the patch between them plain unshielded solid phone wire? Do impedance mismatches make any difference at these rates, or should I just be worried about how many feet of wire are exposed to EMI, or are the noise margins good enough that I shouldn't even worry about that? I suppose it's obvious, but I guess I should mention that we're talking RS-232. -- Roy Smith, {allegra,cmcl2,philabs}!phri!roy System Administrator, Public Health Research Institute 455 First Avenue, New York, NY 10016 "you can't spell deoxyribonucleic without unix!"