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Diamond NR73BNMO troubleshooting

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by KI7OIH, Dec 31, 2018.

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  1. KI7OIH

    KI7OIH Ham Member QRZ Page

    Hi all, I am working on my mobile setup and am having issues with my Diamond antenna. I have checked my NMO mount's continuity back to the PL-259 connector and am seeing no issues. I moved on to troubleshooting the antenna and checked continuity from the center spring pin to all the antenna set screws and I am not seeing anything. I am however seeing continuity from all the set screws all the way up to ground. The very top set screw I am seeing about 22k ohm to ground. Is it normal with this antenna for me to not see any continuity with the center pin?

    I tested my magnet mount TRAM antenna and was seeing continuity just fine with the center pin up the antenna.

    Anyone have any advice?
  2. NH7RO

    NH7RO Ham Member QRZ Page

    Antennas radiate RF which is AC, not DC---so where there's "continuity to ground" may be perfectly normal depending on how it's loaded (just as "no continuity" may be normal as well). Have you checked the SWR with a small bit of power applied yet?

    Probably nothing to worry about unless it seems unusually high.
  3. NL7W

    NL7W Premium Subscriber QRZ Page

    I had one of these. A new antenna, I chucked it after finding its reflected power climbing after two or three seconds at 50 watts.

    I went back to the Larsen NMO-270B, which seem to last 10 to 20 years before the internal matching cap fails.

    Stick with the best. That's Larsen.

    BTW, my public safety 2-way radio shop relies on Larsen 800 MHz antennas. I cannot remember the last time we've had a Larsen fail on that band.
  4. AA5MT

    AA5MT Ham Member QRZ Page

    I had one of these too. Mine went bad at the pressure fitting inside. I don't like non-solder joints. I think it showed dc continuity.


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