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Alternator Noise?

Discussion in 'Communication (CB | GPS | HAM)' started by Danswift79, Dec 29, 2001.

  1. Danswift79

    Danswift79 Registered Member

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    OK Guys and Gals, I got a ? for ya. When I am cruising around and I turn on the CB, Iget a whining noise that gets faster the faster the RPMs are. I have been told that this is alternator noise and there is nothing that I can do about it. This is on a 79 blazer with a Midland 77-882 series(1976 model). I hav a magnetic hustler antennae mounted on the roof and can pick up and broadcast at about 3 miles during the day. I have 1.1 at 1 and 1.8 at 40 and this is the best SWR rating I can get with this antennae. That puts me at about 1.4 at 19 which I am told is alright for a 4-Wheeler. In just can't stand the whine anymore. Will changing the alternator help this or what? The Power and Ground run straight from the battery. PLease help!!!

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  2. The_Sandman_454

    The_Sandman_454 1/2 ton status

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    I've been told that grounding the case of the alternator directly to the battery helps, as does putting a fairly large capacitor in the negative cable of your CB wiring. I've not tried it yet. Also perhaps you might try putting a condenser on the output of the alternator. I think a condenser is what you want there. [​IMG]

    You're running resistor wires and plugs right? Might want to try changing out your condenser in the distributor too, it's purpose is to help as a noise filter... [​IMG]

    Also, route the wires as far away from the ignition wires as possible, and as far from the alternator as possible.

    What I'm going to likely do to combat the problem in my rig is to see what happens when I run a coaxial cable for each power lead. I figure the metal shielding around it might help keep pulses from the alternator out of my power. [​IMG]

    1.1 to 1.8 swr? That's quite a difference. Is the antenna all the way down in the base? If it is, you might need to trim it... My Wilson 5k has an SWR of about 1.1 or there abouts basically flat across the channels... [​IMG]

    Make sure and ground the case of the CB if you've not got it mounted to a metal surface (but then again in a 79 blazer there's not much plastic around anyhow)...

    Tim
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  3. 8_YOUR_H2

    8_YOUR_H2 1/2 ton status

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    You could always try throwing on a $10 noise filter from radio shack too. Although this has never totally eliminated the noise when I have tried it.
     
  4. rebelk5frk

    rebelk5frk 1/2 ton status

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    The first thing to do is check and see if the noise is coming in through the antenna or the power wires. Disconnect the coax from the back of the radio and see if the noise is still there.

    If the noise is still there with no antenna attached then it is much easier to take care of the problem. A cheap noise filter on the power wires or grounding the chassis of the radio or adding a small capacitor on the power wires.

    If the noise dissapears when you take the antenna off then the noise is being radiated to the antenna and it's a bit harder to get rid of the noise. Many times it might be as simple as moving the antenna to a new location. If that doesn't work then you have to find the actual source of the noise and eliminate it there. Radiated noise can be a real pain to track down and solve but it can be done.

    Do that little test and if you can't get rid of the noise then let me know and I'll give you some more tips for finding it and/or solving the problem

    good luck
     

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