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CB SWR changes with mic location

Discussion in '2nd Gen. Tacomas (2005-2015)' started by AStinkyBumb, Sep 8, 2018.

  1. Sep 8, 2018 at 4:23 PM
    #1
    AStinkyBumb

    AStinkyBumb [OP] Well-Known Member

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    I am attempting to install my first CB, I used the guide here to install the CB in my center console then run a 10" cable to the front. I have an external speaker in the little cubby next to the 4wd knob. Power for the CB and the aux cable for the speaker are both run under the shifter and up to the dash. Coax runs under the driver seat and back through the cab, along the bed and to an antenna that is on a tailgate mount. I was initially having grounding issues with the antenna until I ran a ground wire for it. This got my SWR readings down under 3.

    First issue: when I use the right angled 10" extension I always get a +.5 to +1 swr reading compared to just plugging the mic into the radio. Does a 10" extension to the mic really add that much of a difference?

    Second issue:
    If I key the mic holding it above the passenger seat I get a reading of 1.5/2.0 (ch1/ch40)
    If I key the mic above the driver seat I get a reading of 2.0/2.7
    If I key the mic above one seat then move it around the SWR needle will move around between the 1.5 and 2.7 some times 3.0

    I understand I wont have great tuning with a 2' antenna but I cannot get the SWR consistent. Then to top it off I dont know if anyone can hear me cause I have no one to test with.

    Here are the parts I am using:
    2' Firestik
    Workman 10" extension: https://www.amazon.com/gp/product/B00GKRMDE8/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1
    Astatic SWR Meter: https://www.amazon.com/gp/product/B00K87CFK8/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1
    Midland 1001LWX: https://www.amazon.com/gp/product/B00176RNLA/ref=oh_aui_detailpage_o00_s01?ie=UTF8&psc=1
     
  2. Sep 8, 2018 at 5:56 PM
    #2
    potstech

    potstech Well-Known Member

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    Check for pinched cables. Also check to see if your console is a true battery ground and the chassis is grounded to the negative side of the battery. Also is you antenna on a metal portion of your truck. If not you need a metal plate under it to provide a "ground plane" .
     
  3. Sep 8, 2018 at 6:04 PM
    #3
    AStinkyBumb

    AStinkyBumb [OP] Well-Known Member

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    No pinched or coiled cables, that was the first thing I checked.
    CB is wired directly to my aux fuse panel which is tied into the battery ground under the hood.
    Antenna is mounted on a Firestik stud, heavy duty stainless spring all mounted to a Rago fab tailgate bracket. I have also added a ground wire from the bracket to a frame bolt under the bumper.

    Before I added the bracket ground my SWR was 3.5+ no matter what I did.

    If I plug the mic directly into the CB and key it over the passenger seat I get pretty decent SWR for a 2' antenna. The moment I move it closer to my body it moves all over the place and gets a worse SWR reading.
     
  4. Sep 8, 2018 at 6:17 PM
    #4
    jboudreaux1965

    jboudreaux1965 Ragin Cajun Fan

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    How long is the ground wire on the radio? Get on Chan 19, ask for a mic check.
     
  5. Sep 8, 2018 at 6:19 PM
    #5
    AStinkyBumb

    AStinkyBumb [OP] Well-Known Member

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    Ground and power wire that was on the radio out of the box was maybe 3' long. I extended both to reach my aux fuse panel. They are maybe 6' in total now with a crimp in the middle for the extension.

    *Edit* - I jumped on channel 19 and asked for a radio check, got nothing back. Drove over close to i69 and did the same for nothing. I can't hear anything on any of the stations. NOAA comes in clear as day though. But 19 is dead around me.

    I am not sure if it's dead because I'm not picking something up or if there is just no one talking.
     
  6. Sep 8, 2018 at 6:29 PM
    #6
    jboudreaux1965

    jboudreaux1965 Ragin Cajun Fan

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    My bet, ground wire is too long, try finding a good solid ground point close to the radio. Maybe scrape a spot clean on the body (floor) close as you can to the radio and use a good self tapping screw to ground it.
     
  7. Sep 8, 2018 at 6:35 PM
    #7
    AStinkyBumb

    AStinkyBumb [OP] Well-Known Member

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    Should I snake it out of the cab and try grounding directly to the frame or are there bolts inside the cab that are connected to something solid I could try hitting?
     
  8. Sep 8, 2018 at 6:35 PM
    #8
    jboudreaux1965

    jboudreaux1965 Ragin Cajun Fan

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    What's the mount look like? Where did you ground the wire you used to ground the antenna?
     
  9. Sep 8, 2018 at 6:38 PM
    #9
    AStinkyBumb

    AStinkyBumb [OP] Well-Known Member

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    Mount is this rago fabrications tailgate mount.

    I used a ring terminal around one of the top bolts and ran 14g wire down the tail light to the a bolt on the bumper frame.

    Honestly this helped a ton because before I grounded it my swr wasnt ever below 3. Once i grounded it i was able to get better readings they just aren't consistant.
     
  10. Sep 8, 2018 at 6:54 PM
    #10
    jboudreaux1965

    jboudreaux1965 Ragin Cajun Fan

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    I text a buddy who is a cb expert...

    "When keyed, why would SWR's skyrocket when the mic gets close to your body?"
     
  11. Sep 8, 2018 at 6:55 PM
    #11
    jboudreaux1965

    jboudreaux1965 Ragin Cajun Fan

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    "Cause rf is coming back through the mic most likely"
     
  12. Sep 8, 2018 at 6:56 PM
    #12
    AStinkyBumb

    AStinkyBumb [OP] Well-Known Member

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    I tried taking a video today but needed a 3rd hand. I can try getting one tomorrow with the help of my wife to see if I can show what's going on.
     
  13. Sep 8, 2018 at 6:57 PM
    #13
    jboudreaux1965

    jboudreaux1965 Ragin Cajun Fan

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    "Through its ground. Usually means shit ground on antenna or on coax connectors"
     
  14. Sep 8, 2018 at 6:59 PM
    #14
    AStinkyBumb

    AStinkyBumb [OP] Well-Known Member

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    I will have to try re grounding the radio tomorrow and maybe move my antenna ground.

    I have read you aren't supposed to ground directly to the antenna but on the mount. Could the powder coating be throwing it off at the antenna mount?
     
  15. Sep 8, 2018 at 7:02 PM
    #15
    jboudreaux1965

    jboudreaux1965 Ragin Cajun Fan

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    I'm good with cb's, he has 20 years experience installing and repairing them. Yes, good bet that the coating on the mount is interfering with ground.
     
  16. Sep 9, 2018 at 3:49 AM
    #16
    AStinkyBumb

    AStinkyBumb [OP] Well-Known Member

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    I know from past experiences that unless terminals are touching metal they normally have a bit of an issue but this bracket was so small and i figured with it being so low powered that a ground wasn't necessary or would have any issues with the powder coating.

    After I started reading into it i guess a lot of people are running ground wires since the beds are mainly composite. I will re-ground everything later tonight when I get a chance and test round 2. Its been non stop raining here so I am cramped in my garage then have to run through the rain to test the antenna.
     
  17. Sep 9, 2018 at 12:00 PM
    #17
    AStinkyBumb

    AStinkyBumb [OP] Well-Known Member

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    It was 100% the antenna bracket ground. I rubbed and chipped away the powder coating on the bottom where the stud meats the bracket then I chipped away some around the bolt where I ran the ground. Hooked it up to the SWR and boom 1.4/1.5 after tuning. No matter where I moved the mic it stayed still at those two.

    Thank you a ton!
     
  18. Sep 9, 2018 at 3:12 PM
    #18
    jboudreaux1965

    jboudreaux1965 Ragin Cajun Fan

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    Just glad you got it up and running :)
     

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