Lab 5.3.1 Basic Cable Tester

Estimated time: 30 min.

Objectives:

• Use a cable tester to verify that a straight-thru or crossover cable is good or bad

UTP Ethernet Cabling: Cabling is one of the most critical areas of network design and implementation. The cabling is expected to last from 10 to 15 years. The quality of cable and connections is a major factor in reducing network problems and time spent troubleshooting. Unshielded Twisted Pair (UTP) copper cable is the most common cable used in Ethernet networks. There are various Categories (CAT 3, CAT 5, CAT 5e etc.) but all of them contain 8 wires or conductors and use RJ-45 connectors. A UTP patch cable in a network is usually wired as a straight-thru or crossover. In order to follow proper specifications, all 8 conductors must be used even though with most earlier versions of Ethernet, not all 8 conductors were used. You will create these cables in the future labs. In this lab you will work with several cables that have already been made and will test them for basic continuity (breaks in wires) and shorts (2 or more wires touching) using a basic cable tester. (refer to the lab on resistance measurements).

Basic Cable Testers: There are a number of very simple and inexpensive basic cable testers available (less than $100). They usually consist of one or two small boxes with RJ-45 jacks to plug the cables to be tested into. Many of these are designed specifically to test only Ethernet UTP type of cable. The testers will have more than one jack to allow for testing of straight thru or crossover cable. Both ends of the cable are plugged in to the proper jacks and the tester will test all 8 wires and indicate whether the cable is good or bad. If any of the eight wires has a break or is shorted to any of the other wires, the cable is bad. The simple testers may just have a single light to indicate this; others may have eight lights to tell you which wire is bad. These testers have internal batteries and are doing continuity checks on the wires.

Advanced Cable Testers: Advanced cable testers, such as the Fluke 620 LAN CableMeter, are sophisticated cable testers which have basic cable testing functions and much more. You will use an advanced cable tester in future labs to do wire maps etc. If an inexpensive basic cable tester is unavailable, the Fluke (or equivalent) is more than adequate. Advanced cable tests can cost from hundreds to thousands of dollars.

Prior to starting the lab, the teacher or lab assistant should have several basic cable testers available (one for each team of students) or several Fluke Cable meters and various lengths of wire with induced problems. Work in teams of two.  The following resources will be required:

• Basic cable tester
• Advanced cable tester (Fluke 620 or equivalent)
• 2 lengths of good CAT 5 cable (one crossover and one straight-thru, use different colors or labels)
• 2 lengths of bad CAT 5 cable (one with a break and one with a short, use different colors or labels)

If you are using a basic cable tester, refer to the instructions from the manufacturer and insert the ends of the cable to be tested into the jacks accordingly. If you are using the Fluke 620, use the following instructions to test the four cables. Insert the RJ-45 from one end of the cable into the UTP/FTP jack on the tester and turn the dial to test. All conductors will be tested to verify they are not broken or shorted. (Note: this test does not verify that the pins are connected correctly from one end to the other)

Step 1 - For each test, insert the cable into the RJ-45 jack(s) of the cable tester and record your results below: