I have an older VAL 760 TSO COM radio. Twice now the radio has blown an internal radio fuse on transmit. VAL has tested and certified the radio as "Good", but advice that the cable or antenna could be faulty. How does one test that the antenna or cable is adequate? Can one use an ohm meter to check for resistance or continuity? Any other advice is appreciated. I have a newer VHF antenna. It may be a CI-101, although not positive.
Your radio shop may be able to test the SWR of the antenna working with the COM radio. That would be my starting point. However, sometimes problems like these are intermittent and difficult to isolate.
You can test the antenna with an ohm meter but that will not measure the impedance at transmit frequencies. An SWR meter will.
Unfortunately, unless your other hobby is ham radio, you may not have the equipment on hand to check out transmitter operation. But your radio shop will.
They will also have a dummy load for testing the transmitter.
I have to say that I am surprised that the unit blew a fuse. Most aviation radios I have experience with (I am not an avionics tech only a ham) have protection against shorts or opens on the output of the transmitter, which usually shut down the power of the transmitter, for example when a high reflected signal comes back. So blowing fuses is normally extremely rare.