Coax

[chad2072]

Hey all!

I just ran new coax cable through my mast (the last owners used a handheld). My dilema...how do I test it with an ohm meter to make sure its good? I have the antenna hooked up to it but the other end doesnt have anything on it yet. I've heard that you stick one probe in the middle wires and the other one on the outer wires and it should read infinity?

[Viking Sailor]

The reading you get with a multimeter depends on the design of the antenna. Some antenna's will read open while others will read shorted.

If you have a reason to suspect a shorted coax then disconnect the antenna and check for the short. On the other hand, if you think that the coax is broken then short out one end of the coax and check for a short at the other end.

What you want is for the coax and its connectors to pass the above tests and the coax connectors to be free of dirt and corrosion.

[Wotname]

Some addtionial information to VS's post. The DC measurements are a good starting point but will not tell you the efficiency of the coax to transfer the RF from the radio to antenna (or vice versa). This should be done with SWR meter. There is a lot of information on the communications threads on CF on this subject.

[Steve Rust]

One of my careers was building and installing video conference systems in corporate boardrooms. In the process I have pulled tens of thousands of feet of coax cable. Seldom if ever is there a problem with the cable. The problems occur either in damaging the cable during the pull or faulty termination or abuse at the connector. Check for a short by disconnecting the antenna and check for continuity between the braided shield and the center conductor at one end. If you need to check it for a break(unlikely) you will need to get at both ends.