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Qualcomm problems with CB?

Discussion in 'Trucking Electronics, Gadgets and Software Forum' started by Displaced Yooper, Oct 23, 2011.

  1. Oct 23, 2011 #1
    Displaced Yooper

    Displaced Yooper Light Load Member

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    Oct 18, 2010
    Detroit, MI
    0
    We run MCP200 Qualcomm units, and I've been complaining of blue-screens & lock-ups since I first signed on here. I'm on brain box #4 after 10 months running with the system. Replacing the box seems to be the only answer to Qualcomm problems, I guess... Finally figured out what's been doing it all along.... my CB!
    Mind you, I'm not running any king of fire breather, and no linears. Just a mildly tuned General Lee that's been professionally aligned. No splatter & it's on channel.
    As long as I keep the CB turned off, or at least only listen, and never transmit, the Qualcomm unit works just fine. As soon as I key up, it will either freeze on whatever screen it's on (usually the nav system), or go directly into a blue-screen & reboot.
    I've run down the power & data connections to the black box & there seems to be no problems there, and the CB coax doesn't come anywhere near them, nor does the CB's power wires.
    The brain box is mounted under the bed in the passenger-side rear of the bunk, and the CB is on the dash, with the antenna coax being run behind the dash & out the driver's-side footwell through the firewall, then along the underside of the cab & up the driver's side rear of the sleeper the the Outback bracket & SkipShooter antenna I run.

    Has anyone else run into a problem like this? Is the CB just throwing out too much power & attacking the brain box with a bunch of RF, or is there likely a different problem? The CB puts out a touch over 50 watts swing on a Bird meter w/ a swing kit, so I'm trying to find someone with a rock-stock CB to borrow & try out. If I have to go to a lower powered CB, so be it, but I just hate the idea of buying yet another CB just to find out the problem lies elsewhere.
     
    Displaced Yooper, Oct 23, 2011
    Displaced Yooper, Oct 23, 2011
    #1
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  3. Oct 23, 2011 #2
    Mark Kling

    Mark Kling Technology Contributor

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    Sep 23, 2007
    Statesville, NC
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    I would suspect the QC black box is not heavily shielded. So your RF may be bleeding over into the black box.

    The black box cables should be ground by internal shielding.

    You might try this. Buy some chicken wire, the smaller the openings the better. Wrap it around the black box and under it. So basically unscrew the black box, wrap it in chicken wire and then bolt it back down. Make sure you have the chicken wire going to a good ground.

    The chicken wire will "capture" the stray RF and shunt it to ground.

    I used to work on 400 SSB amps and with the lid off you get a ton of stray RF. I build a plastic top with chicken wire sandwiched between and shunted to ground. We tested with an RF meter and it shunted about 99% of the stray RF back to ground.

    mark
     
    Mark Kling, Oct 23, 2011
    Mark Kling, Oct 23, 2011
    #2
    Displaced Yooper Thanks this.
  4. Nov 16, 2012 #3
    codeshane

    codeshane Bobtail Member

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    Nov 16, 2012
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    Mark is 100% on the money about RF shielding; however, if you are running your CB through the pre-installed coax then I think you may be facing a different problem.

    The factory routes the coax from the antennas to a little multiplexer under the dash. The multiplexer allows multiple devices to share an antenna (or antenna-pair in our case) with multiple devices. You'll find it often provides reception for the CB, the stereo with weather bands, and a TV coax in the sleeper berth.

    This multiplexer is *cheap* in every sense- with "affordable" construction causing it to suffer in build quality and performance. Heck, the coax is hard-wired in with some sealant for good measure. If you're lucky, the multiplexer will do what it was meant for, but nothing more. Since no CB radio in the United States is manufactured to transmit above four watts, that's the most you could hope it will handle (and the same goes for stock coax and antennas.) It will also be full of static, etc.

    A CB "peak & tune" will push a typical CB's output into the 8-18 watt range. Since that energy has to go somewhere, it can affect other devices. While most damage is done directly (ever burn out your stereo?) digital electronics (MCP200, MAS200, ECM, and other computers) are much more sensitive to damage from this redirected current.

    I suspect these issues will be relieved by mounting and tuning another (quality) antenna with it's own separate coax line. As a bonus, you can expect greater range for receive and transmit thanks to cleaner signals and less energy bleeding into your stereo, Qualcomm, and portable DVD-player.

    Also, if you're still driving for the Big Orange, their shops stock antenna mounts (much cheaper than replacing Qualcomms) though I recommend buying proper antenna(s) and coax yourself.
     
    codeshane, Nov 16, 2012
    codeshane, Nov 16, 2012
    #3
    Displaced Yooper Thanks this.
  5. Nov 17, 2012 #4
    Displaced Yooper

    Displaced Yooper Light Load Member

    152
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    Oct 18, 2010
    Detroit, MI
    0
    I've already run new coax and mounted the antenna on an Outback bracket, as I stated in my first post. The antenna is an adjustable Skipshooter.
    I ended up pulling out my (very) old Cobra 148 & running that in place of my General Lee. Only about 18-20 watts compared to well over 50 w/ the General Lee. No further problems w/ the Qualcomm since then.
    The fact that the floor of my T2000 is composite with no metal, and that's what the QC's black box is mounted to, means no grounding to the box. It shouldn't have surprised me that it was so vulnerable to RF.
    If I planned on pulling pumpkins any longer than necessary, I'd ground the box proper. But once the wife & I sign our mortgage on our house, I plan on hitching up to a skateboard before the ink is even dry. Goodbye Omaha Orange & E-Logs, Hello respectable rates & loose-leaf logs!!!
     
    Displaced Yooper, Nov 17, 2012
    Displaced Yooper, Nov 17, 2012
    #4
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