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  • No AM Radio Signal

    After much work, the Boomzbox radio by MP3car is up and running...but only FM. It is powered through the computer's 12 volt rail. The antenna is plugged in. The original antenna jack worked without any sort of adapter.

    While testing, the AM radio signal worked well enough. I was only using a screwdriver stuck into the antenna port. I also used a long wire. AM and FM worked.

    Now that it is in the car, with the real antenna plugged in, there is NO AM signal. FM is strong and clear with HD channels. But no AM. There is a little static.

    So what's up with this? Do I need to mod the antenna? Stick an AM antenna wire in the jack?

    Thanks,

    DJ

  • #2
    stop sticking things into jacks!

    you provide no information on your car
    maybe its got a special antenna, that is amplified
    also... am is very tricky in a car
    -Thanks
    Mitch
    www.rush2112.net

    "Did you test it in carwings??"

    Sun, Come shine my way
    May healing waters bury all my pain
    Wind, Carry me home
    The fabric of reality is tearing apart
    The piece of me that died
    Will return To live again

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    • #3
      Originally posted by djkinney View Post
      After much work, the Boomzbox radio by MP3car is up and running...but only FM. It is powered through the computer's 12 volt rail. The antenna is plugged in. The original antenna jack worked without any sort of adapter.

      While testing, the AM radio signal worked well enough. I was only using a screwdriver stuck into the antenna port. I also used a long wire. AM and FM worked.

      Now that it is in the car, with the real antenna plugged in, there is NO AM signal. FM is strong and clear with HD channels. But no AM. There is a little static.

      So what's up with this? Do I need to mod the antenna? Stick an AM antenna wire in the jack?

      Thanks,

      DJ
      i suspect your antenna is amplified, you'll need a way of powering the amplifier, sometimes the 12v runs down the central conductor of the coax but you need to check. Some are externally powered.
      The epitome of Function over form and is probably the best Car PC in Europe.
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      • #4
        O.K. So... powered or not, it worked with a very UNPOWERED copper wire as an antenna in my workshop. I then plugged in the appropriately shaped male into female and have perfect FM.

        The car is a 2007 Mazda MX5. Stock stereo stuff before I gutted it.

        So are you saying that the antenna wire itself is/was powered? If it worked with a copper wire, I really just assumed that any long piece of metal would act as an antenna.

        Comment


        • #5
          he didnt know if your antenna was powered or not, since you didnt even mention what kind of car you had

          and yes, if it is ampilified, it needs to be powered for AM and FM

          antennas today are much more than "long pieces of metal"

          but, if the car has a mast of approx 30" long, its not amplified

          i cant find a good picture of that car, but it looks like a little antenna
          and thats prob ampilfied!

          turn on the amp!
          -Thanks
          Mitch
          www.rush2112.net

          "Did you test it in carwings??"

          Sun, Come shine my way
          May healing waters bury all my pain
          Wind, Carry me home
          The fabric of reality is tearing apart
          The piece of me that died
          Will return To live again

          Comment


          • #6
            The amp, I'm assuming was in the stock stereo. That's gone now. Because the FM is working, would it not be possible to splice in an AM antenna (you know, like one of those long coils of wire on a square spool for a home stereo system) and embed that somewhere behind the dash?

            As I said, powering the antenna at the correct power levels is not an option if there is an alternative.

            Comment


            • #7
              id bet knowing mazda, the amp for the antenna is in the antenna...
              power on the power antenna control wire on the factory radio harness
              (blue wire in the 1H position)

              otherwise, be happy with FM....
              -Thanks
              Mitch
              www.rush2112.net

              "Did you test it in carwings??"

              Sun, Come shine my way
              May healing waters bury all my pain
              Wind, Carry me home
              The fabric of reality is tearing apart
              The piece of me that died
              Will return To live again

              Comment


              • #8
                So it's your opinion that the power flows from the harness to the antenna plug and along the antenna to the amp? And by using a multimeter I should be able to figure out how much power and send it along the antenna...

                But what about the Boomzbox? That will introduce a current into the antenna jack. Will that harm it?

                I paid $180 for a radio...more than any other single part of my carpc install. It is GOING to work.

                Comment


                • #9
                  there is NO OPINION here

                  there is a wire on the factory harness that powers up the the amplified mounted at the base of the antenna
                  (if its all factory stuff of course)
                  (you can see the module at the base of the antenna in the trunk)

                  im sure it takes 12Volts!!!!!!

                  it doesnt send it "along the antenna" its its OWN wire




                  its has nothing to do with the boomzbox radio...
                  and what does cost of the "radio" have to do with anything here
                  -Thanks
                  Mitch
                  www.rush2112.net

                  "Did you test it in carwings??"

                  Sun, Come shine my way
                  May healing waters bury all my pain
                  Wind, Carry me home
                  The fabric of reality is tearing apart
                  The piece of me that died
                  Will return To live again

                  Comment


                  • #10
                    You're mistaken. There is no module on the antenna in this model. It is an antenna that has a long cable that plugs into the "antenna in" jack in the old stock unit and in the boomzbox. No sep. wire. So the power source--the wire at the harness--has nothing to plug into.

                    That's my problem. I don't know what to do with the 12 volt wire from the harness.

                    That's what I mean by "along the antenna"... because there is just one wire to and from the antenna.

                    Comment


                    • #11
                      is that not a FACTORY OEM ANTENNA???!?!?!?!?!
                      if it is, its amplified, i have the wiring diagram for your 2007 miata
                      the wire isnt WITH the ANTENNA lead, its on the factory harness
                      maybe you should take your car to a car stereo store
                      or at least i think you would be using a Metra Harness
                      like i said before BLUE wire
                      -Thanks
                      Mitch
                      www.rush2112.net

                      "Did you test it in carwings??"

                      Sun, Come shine my way
                      May healing waters bury all my pain
                      Wind, Carry me home
                      The fabric of reality is tearing apart
                      The piece of me that died
                      Will return To live again

                      Comment

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