If your cable, Internet, or satellite signal falters, but all equipment seems to be functioning properly, the problem could reside in the coaxial cable carrying the signal. A simple way to test this is to replace the cable; however, if you do not have an extra cable to spare, you can test for a short or break in the line with a multimeter. Since coaxial cables are rated for a stable resistance across the length of the cable, the ohms setting on a multimeter is perfect for performing such tests.
Instructions
1. Set your multimeter to an ohms scale around 100 ohms. A higher scale works, but avoid moving into a scale close to 1k ohms or higher. Coaxial cable is typically rated to operate at 50 or 75 ohms so the scale should be at or greater than these ratings.
2. Disconnect both ends of the cable from their connections.
3. Test the length of the cable by placing a multimeter probe on each end of the cable, touching the center wire emerging from the coaxial connector.
4. Read the multimeter display. A reading around the 50 ohm or 75 ohm rating of the cable indicates that the cable is working properly across its length. A reading of infinite resistance indicates a break somewhere along the the inside of the cable. A reading of zero indicates a potential short between the inner cable and its shield.
5. Remove the cable connector to expose the cable shielding.
6. Place one multimeter probe on the cable shielding and the other on the inner cable.
7. Read the multimeter display. A reading of infinite resistance indicates no short between the shield and the inner cable. A reading of anything below infinite indicates the shield and inner wire may be touching somewhere along the cable. If this is the case, the reading will be closer to zero.
Tags: inner cable, across length, cable reading, cable shielding, display reading, infinite resistance, infinite resistance indicates