How to Check the Coaxial Cable in a Ham Radio
- 1). Coil up the entire length of coaxial cable so that both of the connecting ends are positioned in front of you.
- 2). Turn on the digital multimeter and set it to measure resistance, measured in ohms, or set the multimeter to provide a continuity tone if your specific device has this built-in audible continuity feature.
- 3). Touch the red test probe to the center pin of the coaxial connector on one end of the cable and hold it firmly against that center pin. While continuing to hold the red probe against one center pin, touch the black test probe to the center pin on the other end of the coaxial cable. If you see the multimeter displaying a series of numbers on the screen, or your meter is giving you a continuity tone, then the center wire of your coaxial cable is in excellent shape and remains unbroken. If there is no ohm reading or continuity tone, then the coax cable needs to be replaced.
- 4). Continue holding the red test probe to the center pin on the same end you had placed it in the previous step, and remove the black test probe from the center pin on the other end. Touch the black probe to the metal barrel of the connector. At this point, you should be touching the center pin with the red meter probe on one end, and the metal barrel connector with the black meter probe on the other end. If the meter displays "1" with no other digits after the decimal, or the meter fails to emit a continuity tone, then this means the center wire and the outer mesh of the coax aren't shorted and your coaxial cable is healthy. If you do get an ohm reading or a continuity tone between the center pin and barrel connector, then your coaxial cable is shorted and must be replaced.
- 5). Perform a visual inspection of the outer cable insulation to ensure it isn't breaking down or cracking from exposure to weather. If the coaxial cable is breaking down to the point where many cracks are visible, the cable should be replaced with a new one. Cracks in the outer insulation permit rain and humidity to make contact with the outer mesh braid wire of the coaxial cable, which will eventually oxidize it and make it unfit for use in transmitting a signal.
