Ball mount with SO239

Discussion in 'Discussions, Opinions & Editorials' started by W5DMG, Nov 6, 2012.

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  1. W5DMG

    W5DMG Ham Member QRZ Page

    I have been looking for a ball mount for my car that has an SO239 to mate with the antenna.
    But no one makes them, at least not yet.
    I emailed Jerry Breedlove about why these are not common.

    He said he has had many requests for them, but he had not found a way to make it.
    I told him I thought to just attach an SO239 chassis mount to a flat surface of the ball.
    Make sure that the center conductor of the 239 connects to the ball. Then attach a
    insulated wire to 1 of the 4 holes of the chassis mount and run it outside to the
    back plate. I was not real sure if that would work, but sounded proper.

    He replied back :

    I am looking for feedback on his reply...
  2. KY5U

    KY5U Subscriber QRZ Page

    The problem is that the ball mount is basically the center of the so239. The thread should be ground, but in the typical ball mount, the coax ground is attached to the car chassis and the center conductor to the ball. See the problem? The threads for the SO239 are sitting up on the ball with no way to get a ground from the chassis of the car down at the bottom. You can no doubt homebrew something.
    Last edited: Nov 6, 2012
  3. WA7KKP

    WA7KKP Ham Member QRZ Page

    au contraire, they were made. My dad had one, made by Master Mobile. Might have been an add-on, as it would bolt right over a standard sized ball mount. And I had one that was (I believe) made by Antenna Specialists.

    Why don't you do a little homebrew, starting with a soup can or similar item. If you're handy with snips, you could whittle one out in an hour or so. Just add an SO-239 jack, or maybe using a threaded barrel, and extend the screw with some running thread long enough and fat enough to fit snugly in the end. Or put it out the side, depending on what you need.

    Having it (or not) won't make much difference in your mobile installation, except make it look kinda spiffy. Most hams simply peeled the coax back and attached it with lugs.

    Gary WA7KKKP
  4. KY5U

    KY5U Subscriber QRZ Page

  5. K9STH

    K9STH Ham Member QRZ Page

    Ball mounts with an SO-239 were definitely manufactured for commercial two-way services in at least the 1950s and 1960s and probably later. Somewhere I have one such mount that was used in a low band system.

    Glen, K9STH
  6. WA4BRL

    WA4BRL Ham Member QRZ Page

    High Sierra makes it and it's only seventeen bucks!



    To see the web site/advert, CLICK HERE
  7. WB2WIK

    WB2WIK Premium Subscriber QRZ Page

    I looked at the High Sierra one, too, and can't figure out how the outer conductor of the coax gets grounded anywhere since it appears to be attached directly to the plastic insulator of the mount and not to the grounded ring...

    An accident? Or maybe something going on we can't see?
  8. W5DQ

    W5DQ Ham Member QRZ Page


    If I understand what he is looking for, the SO239 needs to be on the other end of the ball mount where the antenna attaches, not the coax. Some antennas have a PL-259 type of connection that screws onto a matching SO-239 mount.

    I could be wrong but that the way I understand what he is describing.
  9. WB2WIK

    WB2WIK Premium Subscriber QRZ Page

    You might be right.

    A UHF connector will never support an HF antenna, though, other than maybe a short Hamstick. Maybe. It's not designed to be a mechanical support, that's why God made 3/8"-24 stainless steel studs.:eek:
  10. W5DQ

    W5DQ Ham Member QRZ Page

    The infamous ATAS-100 and ATAS-120 mini-screwdriver antennas from Yaesu both use a PL-259 mount format. I had one (-100) for a while and used the Diamond K400 trunk mount and had limited success with it. A buddy tried the same mount with a -120 and could never get it to work correctly.

    Gene W5DQ
  11. W5DQ

    W5DQ Ham Member QRZ Page

    I doubt you will find what you are looking for because to get it to work the center pin and ground would have to be reversed. And to kludge something together will probably break off when stressed under load. Been there done that by having a hamstick break a homebrew mount and had it dragging behind the car (by the coax) in freeway traffic in OKC on I-40 till I could clear traffic and pull over. Lets just say the XYL was NOT pleased!!!!

    You might want to look at the K400 mount from Diamond. It supports a sizeable antenna load if I recall the specs correctly.

    Gene W5DQ
  12. K9STH

    K9STH Ham Member QRZ Page

    I cannot locate the ball mount with the SO-239 connector on it right now. However, it definitely does not require any reversal of connections! Coming from the ball itself is the center pin of the SO-239. The outside insulator is somewhat thicker than those mounts that have a machine screw connection and the mounting nut on the ball is on the outside of the vehicle. The inner part of the mount has the outside of the SO-239 on it with a hole in the center to pass the pin from the ball mount itself.

    The mounting holes in this inner plate match up with those in the outside insulator just like with a "normal" mount and its backing plate. When the machine screws are in place the inside plate (with the outside of the SO-239) centers with the pin from the ball mount. When the machine screws are tightened, the ground connection between the outside of the SO-239 and the body of the vehicle is made.

    I can find a high power load for a low-band antenna that is made to replace the "buggy whip" type of ball mount. That load has a solid plate with the SO-239 mounted. When the machine screws are installed, the SO-239 centers in the original large hole for the ball mount and the ground connection is made through the mounting machine screws. Of course, with the load, the length of the whip is shortened.

    Glen, K9STH
  13. KY5U

    KY5U Subscriber QRZ Page

  14. WB2WIK

    WB2WIK Premium Subscriber QRZ Page

    I think using the PL-259 as a mechanical fixing for an HF antenna is silly. Of course the ATAS antennas are quite small and low wind load compared with most HF mobile whips. It's remarkable they don't break (I suspect some do).
  15. W5DMG

    W5DMG Ham Member QRZ Page

    The High Sierra model has the 239 connector at the wrong location, where the coax connects.
    The antenna I want to use is a new Diamond half wave 6 meter, that is 8 feet tall.
    It has a PL259 connector at the base, just like all their VHF/UHF antennas
    I have tried the Diamond K400C HD mount with a 7 foot tall HF antenna, bad idea.
    The antenna swayed back and forth, would have required guying for it to work.
  16. W5DMG

    W5DMG Ham Member QRZ Page

    Thanks for your input KY5U, I will forward this info to Jerry and then maybe he can order one and figure out how to make a ball mount
    with the adapter being physically part of the mount. Therefore making it stronger, and less parts to break.
  17. K8JD

    K8JD Ham Member QRZ Page

    I serviced a few low-VHF band systems and the vehicles that used the 1/4 wave whips got ball mounts with screw connections for the coax installed. It was a standard item.
    It is simple enough to strip the end of coax and twist the shield up and crimp to a ring terminal and crimp another one onto the center wire and screw them down to the ball mount !
    This arrangement stayed in place until the vehicle was retired !
    Who is afraid to cut the factory installed PL259 off a hunk of coax !?

  18. KY5U

    KY5U Subscriber QRZ Page

    No problem. I tried to listen to what you needed and respond to that, rather than Impress you with my knowledge. That was easy, I just ain't as smart as these guys.
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