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High SWR on 108" whip and Galaxy 959

Discussion in 'CB Antennas' started by stranger, Oct 16, 2011.

  1. stranger

    stranger
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    Hello all,

    Been lurking here for a while but haven't had a good enough reason to post until now.

    I have a Galaxy DX 959 peaked and tuned by Screwdriver/Bell's CB that is hooked up to a 102" whip with a 6" spring. I've had a CB radio and a 108" whip on just about every vehicle I've owned and this is the first time I've had a problem with such high SWR.

    After getting it all hooked up, I checked the SWR and it was over 3.0:1. I figured since it was that high it was probably an inadequate ground, so I bought a grounding strap and lead it from the antenna mount up to a little part of the frame that I ground off to bare metal. No luck, SWR was still over 3! I then took the 6" spring off and put just the whip back in, that time the SWR was even higher!

    I've checked for things like corrosion around the mount and where the spring and antenna screw in - good there. I've checked to make sure I had a nylon washer inbetween the stud and the mount - good there. I figured the grounding strap would solve everything and it didn't do jack.

    I'm lost. Does anyone have any ideas as to what the the problem may be? I hate to molest my antenna and start cutting off 1/8" increments to "see" if that solves the problem, and I hate not being able to use my radio without blowing the finals out. There isn't a single CB shop in my whole state, nor do I know anyone that's any smarter with them than myself (and I consider myself a rookie!)



    Any help/ideas would be appreciated!

    [​IMG]
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  2. BOOTY MONSTER

    BOOTY MONSTER
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    too much radiator too close to the ground-plane .

    welcome to the forum
     
  3. stranger

    stranger
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    Thank you for the welcome and your reply. If I fabricate a little metal bar to extend it out another 6-8" do you think that will potentially solve my problem?
     
  4. hotrod

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    bootys right. im not sure of exact location but from what i
    could tell looks like on a bumper of truck.if so id try a stake hole mount
    on passenger side of bed. and/or faborcate something and put on
    passengerside of bedrail
     
  5. Robb

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    Not what I would choose for an ideal location to mount an antenna. Far from it. You would probably be better served with a mag mount antenna on the center of the truck's roof. Or a solid mount in the same place.

    I think that you might make it work; but the movement of that whip when moving will cause your SWR to fluctuate due to the closeness of the whip to the vehicle's sheet metal. It will compromise the length of that antenna; as the only part successfully radiating will be the portion above the roof line.

    Just $.02 worth . . .
     
  6. stranger

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    Thank you folks for the additional replies. It's actually on a 2nd generation Toyota 4Runner, otherwise if it were a pickup the bed idea would be great. I've always been told and came to believe that nothing can beat a 108" whip for perfomance, so I almost feel dumb using anything else, but at the same time I think it might be defeating its own purpose... well, for now anyway.

    Since it's an SUV (a compact size one at that) it was tough to find an ideal spot for the whip. Where it is now was the best spot I could come up with, and it still is slightly in the way of the drop-down tailgate.

    How far do I need to extend the mount/antenna away from the vehicle to get better SWR? The magnet mount is a good idea but I'm kind of strapped for cash the next few months. I'd love to make the 108" whip work somehow if I could and it's possible.


    P.S. since the radio is peaked/tuned (I think a maximum of 12 watts - good enough for me), is the SWR meter on the Galaxy going to be accurate, or is it slightly higher because the radio has a little extra power? Sorry if that's a stupid question.
     
  7. kb3cbs

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    [​IMG]


    is there fiberglass ring on mount
     
    1 person likes this.
  8. Whiplash-265

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    looks like a black plastic one
     
  9. AudioShockwav

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    Down low is the worst place to mount a whip for a few reasons.
    The best way to solve your problem is to get the antenna up.....not away , but up.bite the bullet get a ball mount and drill a hole in the side of your 4 runner and hard mount it to the side as high as you can.
    Yes I know it is a big step to go drill a big hole in the side of your truck and three little ones for the screws to go through , but as these guys have been telling you there is too much of the whip right next to the metal surface that is going to cause you reflect problems.
    It needs to go up...more of the whip needs to be above the metal even if you have to fab some kind of mount that mounts off the side somewhere.
    If you are not comfortable with drilling a hole in your truck scrap the 102 whip and go get a wilson 1000 or 5000 mag mount and slap it in top of the truck and call it good.
    In the long run the wilson will work just as good if not better than the whip due to what you are lose with the whip hid behind all the sheetmetal.
    Yes the 102 is the most efficent antenna but if you have to mount it in a bad location then it will lose the advantage.
    There are ways to make the swr lower at the feed point and still mount it low like that but you defeat the whole idea of using the longer antenna.
    As for the built in swr meter they are ok...most everyone prefers an external one.
    73
    .Jeff
     
  10. 6.0 Liter

    6.0 Liter
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    You don't have a spare tire rack on the back gate do you? It would help you a lot if you could get it out of the weeds a bit.
     
  11. rattler

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    Looks like a washer under plastic insulator. Remove that and check it.
     
  12. towerdog

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    I dont think you get the benefit of not having metal next to the antenna like I got (fiberglass top) but I also think my antenna looks good with ball and socket mount on the back and side. I got SWR of 1.2:1 with rg-58 routed under door sill and in the side of the bed.

    [​IMG]

    If its on the bumper you gotta get it at least several inches off or its going to reflect power (high SWR), and it also more likely hit and risk shorting out transmitter while you drive down the road.

    Mount it on the top, mount it on the side, or get a mag mount wilson 1000, k40 or firestick. You might do better with the wilson in the middle of the roof as it does not move around and blow sideways in the wind like the 108" whip will do.
     
  13. stranger

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    Thank you all for the additional replies. Yes, as specified in the first post there is a nylon washer between the mount and the stud. I do not have a tire rack on back, otherwise that would be an excellent idea. I think I will have to do what Audio and Towerdog said and put a swivel type mount on the side. I have a solid-body 2nd generation 4Runner, not the removable fiberglass top (like I wish I had). I'll probably go with the swivel mount and put it in the same spot as Towerdog posted, I know most of the antenna will be above the roof line, but I just hope I won't have any more "reflection" problems there since unlike Towerdog's, my top is metal not fiberglass. Thanks again you folks for the help, it'll be a while before I put a swivel mount on there (weather is cold in the midwest and I'm strapped for cash at the moment) but I'll be sure to update when I get one installed, I just hope I can someday get an SWR of 2.0:1 or lower and I'll be a happy guy!
     
  14. Marconi

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    IMO, it is always better to have any antenna high and in the clear of all obstructions. However, back in the days when I was running mobiles, there were thousands of guys running the 1/4 wave whip on the style of bumpers installed on P/U trucks back then. I can't claim they are were all good to go, but, within reason I never saw the affects you guys claim regarding some disastrous reflection problems, and for the most part we never ran those 6" springs. We also didn't expect to see a flat SWR with such installs either.

    Now those antenna with coils, being close to something metal was a problem.
     
  15. 222DBFL

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    If all else fails get a sirio 5000 performer and puck mount it on the roof. That or even a mag mount will work better than the Current way it is setup. A Breedlove puck and a sirio 5000 performer near the rear of the roof of the 4 runner. JMO.
     

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