How to Test the Impedance of a Coax
- 1). Disconnect both ends of the coaxial cable so that they are within reach of the red and black probes on the multimeter.
- 2). Turn the dial on the multimeter, indicated by the horseshoe-shaped "Omega" symbol. Set the operating range to an impedance under 100 ohms.
- 3). Touch one probe to each 18-gauge center conductor pin in the middle of the coax cable ends.
- 4). Look for readings in the 50- to 75-ohm range. This indicates proper operation. Infinite resistance indicates that the center conductor is broken or heavily damaged. A "0" reading means that there is an internal short circuit.