Static on cobra 29lx

Discussion in 'CB Radio Forum' started by chriskc, Feb 11, 2017.

  1. Ridgeline

    Ridgeline Road Train Member

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    choke the coax and see where that leads.

    TO explain a little further, some of it may have been covered on k0bg's site, the coax is acting like an antenna, even if you have a good swr, the outer conductor will extend the center conductor and add to the signal. Because the coax is routed (I assume it is) behind the panels and near some of the trucks electronics, you could be picking up what is called ultrasonic harmonics which appears on the radio, either one or a few channels. in this case, I think you are picking up the instrument cluster's signals - you moving causes it.

    BUT again as I said before, RF is a funny creature, what works for one problem may not work for the same problem in a different situation.
     
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  2. chriskc

    chriskc Light Load Member

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    @Ridgeline i will try that. I will order the choke today or see if RadioShack has one.
     
  3. rabbiporkchop

    rabbiporkchop Road Train Member

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    Probably. Ohmmeter useful as well.
     
  4. chriskc

    chriskc Light Load Member

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    I ask because we just got one here at our shop to use on some other things for a few days. I have an ohm meter used it and it tested good
     
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  5. STexan

    STexan Road Train Member

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    I have a "cheap but expensive" USB charger" that will cause static noise periodically to come through my CB [in a Cascadia] when it's plugged in and charging my iPhone. I only use it when I need to charge 2 devices simultaneously, otherwise I only use the USB charger in the CB and have no issues.

    Just something to consider if you're still having issues.
     
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  6. Ridgeline

    Ridgeline Road Train Member

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    A lot of those chargers are tiny switching power supplies which are so so noisy. When I did the ultrasonic testing last year, they were the most noisiest things we tested, three times the amount of noise than anything else.

    I had an issue with a Pi project that kept rebooting on the driver, so had it pulled out of the truck and sent to me while the truck was down for repairs. I could not figure out why, tested it with all kinds of drop outs and even putting in side the case of my amp to see if it was an issue. It wasn't until I put it into my pickup and used the same cheap USB supply I had in that truck, BOOM three minutes and it would reboot. I built a linear supply which fit into the case and sent it back, never rebooted since.
     
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  7. CW Spook

    CW Spook Light Load Member

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    And those switchers and wall-warts will tear things up on a base as well. My home rig is a Flex SDR radio which lets me see a whole band on the panadaptor, and I can see when my wife or even my neighbor turns on a noise-making appliance or light.
     
  8. chriskc

    chriskc Light Load Member

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    @CW Spook @Ridgeline @rabbiporkchop @STexan so I think I have it figured out. The noise in the video is from my strobe lights. I unplugged my phone chargers that helped a little, and I had both the coax and power wire ran up the same door pillar. So I separated them and it helped more. I'm still going to do the grounding straps, and the coax choke and see if it helps more. Thank you guys for all your knowledge.
     
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  9. chriskc

    chriskc Light Load Member

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  10. craig_sez

    craig_sez Road Train Member

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    My phone charger,sirius on my kenwood stereo dbl din stereo,my tnd tablet alll makes noise...
    Funny thing is if i have stereo on with cb on and i plug in my gps the effects of my sirius drop..Now my gps charger does have a ferrite on it..
    I bought a cpl kits to play around with..