I am curious as to how you will know if the cable you acquire is truly "120 ohm". If you can figure out how to validate it, should be pretty easy to some. 300 ohm twin lead is pretty wide spaced. 75 ohm twin lead is pretty close spaced with pretty fat conductors. I suspect that if I went through my junk I would find it if I could recognize it. 3 meters is not much wire. I wonder how close to spec the commercial stuff is anyway. John Ferrell 6241 Phillippi Rd Julian NC 27283 Phone: (336)685-9606 Dixie Competition Products NSRCA 479 AMA 4190 W8CCW "My Competition is Not My Enemy" ----- Original Message ----- From: "Matt Bennett" To: Sent: Sunday, September 02, 2001 9:36 PM Subject: [OT]: Help! need 120 ohm cat5 cable > I've been searching for a very specific type of cable for Ethernet > testing. In my daytime alter-ego, I work for [a very large computer > manufacturer in Texas], where I design and test Ethernet- testing to the > IEEE specifications (the specifications for Ethernet are free 6 months > after they are issued, by the way; check the IEEE website: > ). The latest thing is Gigabit > Ethernet. In the Gigabit Ethernet testing specification, one of the > tests calls for a very specific cable (section 40.6.1.1.1) to do jitter > testing with- a cable made up of a few sections of 100 ohm and 120 ohm > cat-5 cable. According to ISO/IEC 11801, Category 5 cable (100 MHz) can > be 100, 120, and 150 Ohm (I think) impedance. Pretty much everybody > uses 100 Ohm cable- which makes the 120 Ohm cable virtually impossible > to find. > > I've heard things to the effect that 120 Ohm cable is more commonly used > outside the US, but in my searching, I can't find any sources. Alcatel > used to make some, but they don't make it anymore, and they don't have > any alternate sources. According to a very terse email I got from > Belden, they only deal in 100 ohm Cat5 cable. Every other company I've > contacted about it has come up as a dead end. The total amount I need is > under 3 meters, but heck, I'd buy a 1000' spool if I had to. > > Since this list has members from all over, maybe someone out there could > help me. In particular, I need 120 Ohm impedance, 4 pairs of > conductors, shielded or unshielded Category 5 cable. Help? > > Matt Bennett > > -- > http://www.piclist.com#nomail Going offline? Don't AutoReply us! > email listserv@mitvma.mit.edu with SET PICList DIGEST in the body > > -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listserv@mitvma.mit.edu with SET PICList DIGEST in the body