Liberty CRD Diesel '06: Interference with 2m radio transmissions

Discussion in 'General Motoring' started by K7AAY, Dec 3, 2006.

  1. K7AAY

    K7AAY Guest

    With a Yaesu VX-5 powered from a Radio Shack car cord attached to the
    console cigar lighter socket, I get rapidly repeating noise likened by
    others to spark plug noise; but, no spark plugs on a diesel. Removing
    the card cord and transmitting on battery eliminates the problem.

    I'm about to switch from the VX-5 HT to a Kenwood TM-V7A; how may I
    avoid this problem when installing the mobile transceiver.

    Thank you in advance for your on-topic suggestions.

    73s & best regards,

    K7AAY, Dec 3, 2006
  2. K7AAY

    Dave Guest

    Fuel injectors are the most likely source of the noise.

    First, use a direct connection to the battery terminals. Second, twist the
    connecting wires 2 or 3 twists per foot from the battery to your radio. Third,
    get a GOOD chassis ground connection for the radio.

    If noise persists talk with the CRD service techs regarding slightly slowing
    down the rise time of the fuel injectors or adding a suppression diode across
    the fuel injector coils [it is unlikely you will get any support in this area,
    but worth a try]
    Dave, Dec 3, 2006
  3. K7AAY

    Mike Romain Guest

    If you contact DC, they might send you the booklet on installing a
    transmitter into the vehicle. They get very specific on where the power
    and grounds can be run as well as the antenna wire.

    On GM's for instance, you have to have a 10 ga. dedicated fused power
    and ground line to the battery run far away from any vehicle harnesses
    to avoid voiding the vehicle warranty. Transmitters can interfere with
    things like the ABS and transmission modules, like some TJ's will go
    into neutral when the transmitter is keyed up, and any other electronic

    Here is a link to GM's instructions, I haven't found any online for

    86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
    88 Cherokee 235 BFG AT's
    Canadian Off Road Trips Photos: Non members can still view!
    (More Off Road album links at bottom of the view page)
    Mike Romain, Dec 3, 2006
  4. K7AAY

    K7AAY Guest


    Thank you for your on-topic reply!

    I do have the equivalent for a 2006 Charger Police Edition, which may
    be downloaded from the very last link at and
    will look for a similar "outfitter's guide" for the Liberty.
    K7AAY, Dec 4, 2006
  5. K7AAY

    Red Jeep Guest

    Excellent advice. I would add: fuse both hot & ground for good measure at
    the battery ends of the connections. You could also loop the power cord a
    couple of times and put a ferrite bead on the power leads.

    Always run heavier wire than you think you'll need. It reduces loss and
    someday you might want to put out more wattage.

    If it's a temporary set-up, use one of those gel-cell booster batteried to
    power your radio.

    Red Jeep, Dec 4, 2006
  6. K7AAY

    Ken Weitzel Guest


    With all due respect, don't even think about fusing ground.

    Take care.

    Ken Weitzel, Dec 4, 2006
  7. Great! Now comes the interminably long thread where everyone argues
    this Old Rule once again -- without anyone changing their mind -- and
    with each post starting "With all due respect ..." containing little.

    *plonk* the thread
    Allodoxaphobia, Dec 4, 2006
  8. K7AAY

    Mike Romain Guest

    Fusing the ground is recommended and required to do it properly on a
    GM. If the vehicle loses it's body or engine ground strap connection
    for any reason (like corrosion for one) the starter or alternator or
    body/lights, etc. can use the radio as a ground. This usually lets the
    smoke out of the unit big time.

    I have installed hundreds of transmitters in one contract I had and when
    they came back in for repairs over the years, on about 98% of power
    short issues either vehicle related or transmitter system related had
    the negative fuse blown before the positive one. There were lots of
    cases of blown fuses due to ratty vehicle grounds also.

    86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
    88 Cherokee 235 BFG AT's
    Canadian Off Road Trips Photos: Non members can still view!
    (More Off Road album links at bottom of the view page)
    Mike Romain, Dec 4, 2006
  9. K7AAY

    Guest Guest

    Well, I have a '99 TJ with a 40 watt police radio wired from the battery.
    Noooo problems in 2 years. Automatic, air, GPS etc also.

    When I transmit the GPS loses it's location however.
    Guest, Dec 5, 2006
  10. K7AAY

    philthy Guest

    a ground from the battery is the best way to eliminate that type of noise
    philthy, Dec 6, 2006
Ask a Question

Want to reply to this thread or ask your own question?

You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.