jmc@ptsfa.UUCP (04/11/87)
We want to hook up a SUN 3/50 workstation in a cubicle that is wired
for RG-59 coax and our thin ethernet is RG-58. We therefore have a
impedance mismatch since one coax is 50 ohm and the other is 75 ohm.
Someone told us that if the distances were small we could ignore
the mismatch.
We've been unable to find a suitable impedance matching transformer.
Does anyone know if we really can live with the impedance mismatch
and if so for what length wire or know a place that sells impedance
matching transformers?
--
voice= 415 823-2441
uucp={ihnp4,dual,qantel}!ptsfa!jmc
As SuperChicken says: "You knew the job was dangerous when you took it."byrnes@ge-dab.UUCP (04/13/87)
I'm not sure if the difference in cables will
effect your workstation, but I'd reccommend
against using the wrong cable.
We had a problem where someone picked up a
75 ohm terminator instead of the 50 ohm.
(by mistake).
It took us almost 4 hours to find the problem,
since it didn't show up right away. It was
installed during low load times and the few
workstations which were running seemed ok.
Later when everyone went to work the network
would bomb intermitently.
Replacing the 75 ohm terminator with the
50 ohm one solved all the problems.
Good Luck,
Arthur
Arthur J. Byrnes
UUCP: ...!mcnc!ge-rtp!ge-dab!byrnes General Electric
GEnet: advax::byrnes 1800 Volusia Ave, Rm 4412
Voice: +1 904 258 2507 Daytona Beach, FL 32015
Disclaimer; These views are those only of the author, Arthur.kwe@bu-cs.BU.EDU (kwe@buit1.bu.edu (Kent W. England)) (04/13/87)
In article <2925@ptsfa.UUCP> jmc@ptsfa.UUCP (Jerry Carlin) writes: > >We want to hook up a SUN 3/50 workstation in a cubicle that is wired >for RG-59 coax and our thin ethernet is RG-58. We therefore have a >impedance mismatch since one coax is 50 ohm and the other is 75 ohm. >Someone told us that if the distances were small we could ignore >the mismatch. > Why ask for trouble? If the distance is short, then the thin cable shouldn't cost too much (that's where the "cheap" moniker came from). How are you going to keep track of this kludge so that two years from now and two dozen more workstations from now you will be able to figure where this new glitch is coming from. Visibility into this level (the physical) from your system is tough. These mismatch problems are subtle. It may work now, but I guarantee it won't work later. Save yourself trouble later and install thin cable. Better yet, get thin cable installed once and for all, if you are going the thin route. Save the RG-59 for Gilligan's Island reruns. -- -------------------------------------------- | Kent W. England | | Network & Systems Engineering Group | | Boston University | | Information Technology | | 111 Cummington Street | | Boston, MA 02215 | | (617) 353-2780 | | kwe@buit1.bu.edu internet | | itkwe@bostonu BITNET | --------------------------------------------