Mobile Dual Band Antenna - Diamond vs. Larsen vs. Comet... and Counterpoise Question

Discussion in 'Mobile Radio Systems' started by KE2SJ, Dec 7, 2017.


Which mobile 36” dual band antenna and mount?

  1. Larsen with trunk lip mount

  2. Larsen with mag mount

  3. Diamond with trunk lip mount

  4. Diamond with mag mount

  5. Comet with trunk lip mount

    0 vote(s)
  6. Comet with mag mount

  7. Other

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  1. KE2SJ

    KE2SJ Ham Member QRZ Page

    Hi all,
    I realized that I should have posted this query in this forum; apologies for duplication.

    I've got a 25-year-old 2m Larsen whip on a trunk lip NMO mount (one of the ones with the two screws that bite into the underside of the trunk lid to make a ground connections). Now I've gone dual band and am looking for a suitable antenna. I was planning on buying the Larsen NMO2-70B (35" or so), which would fit right on that NMO mount.

    But the folks at Larsen advised me against that, saying that, with a dual band, I'd be cutting my counterpoise in half and bring my gain down towards zero, especially on 440. The ideal would be to take the dive and drill the two holes in the roof or trunk, but that's not going to happen for the sake of keeping the peace with the car's other driver. Short of that, they said I could try a mag mount, which would be another $50-60 on top of the $70 for the antenna with coil.

    The folks at multiple HROs said hogwash as to the grounding issue with the lip mount and said to just put a Diamond DMN-NR770HBNMO on my Larsen NMO mount. Another store recommended the Comet CMA-SBB-5NMO. None of the stores I contacted recommended the Larsen, which surprised me, since I've had good luck with my monobander.

    In any case, I want the best bang for what few bucks I have. For that reason, I'd prefer to stay with the NMO lip mount I already own. But if it's really going to suck the gain out of whatever dualband antenna I put on it, then I guess I gotta go magmount. And in either case, with dualband antenna should I go with?

    All help recommendations comments thoughts quips etc. are appreciated in advance!!

  2. K0BG

    K0BG Platinum Subscriber Platinum Subscriber QRZ Page

    If you want to take the time, go to my web site, and read the Antenna part of the VHF Options article. The short answer is, buy the NMO2/70, screw it onto the current mount, and never look back.

    HRO personnel have a compensation reason to advise on the Comet, and whomever at Larsen who gave you the information he did, isn't up on his company's published data.
    KD5BVX likes this.
  3. N7WR

    N7WR Subscriber QRZ Page

    I have used the Larson you are considering. In fact the one I have is decades old. I have used it with permanent (hole drilled-preferred) mag, and trunk lip mounts. Works fine with all. Much better antenna than the Comet or Diamond. By the way you can buy a decent mag mount for a lot less than the amount you mentioned
    KD5RJZ and KB0MNM like this.
  4. KD2NOM

    KD2NOM XML Subscriber QRZ Page

    I have been using the Comet SBB-5 with the magmount base for about three months now with my Luiton LT-25 dual band radio and it works fantastic. I drive up and down the NJ Turnpike daily and routinely chat on 2 meter simplex for the 40 mile drive with several folks.

    It performs really well on the repeaters up and down 'the pike' as well. I have no complaints and receive great signal reports.

    The only 'issue' is the wind noise from the antenna coiled portion. Above 65 mph it is noticeable. The antenna is mounted center on the roof - so it's pretty much over my head and offset to the right about 8 inches.
  5. AI7PM

    AI7PM Ham Member QRZ Page

    Larsen, but on a permanent mount.
    KD5RJZ, K6NIK and KD5BVX like this.
  6. N8EKT

    N8EKT Ham Member QRZ Page

    The open coil Larsen NMO270B is the best performing dual band mobile antenna on any mount.

    Keep in mind that stores only exist to make a profit so they tend to steer you to what they make the most profit on.
    KD5RJZ, K6NIK, WD9EWK and 1 other person like this.
  7. W1JCH

    W1JCH XML Subscriber QRZ Page

    Great advice, I was in the market for a dual bander myself!

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