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AM radio interference from fluorescent lights

Post in 'DIY and General non-hearth advice' started by wahoowad, Dec 27, 2007.

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  1. wahoowad

    wahoowad Minister of Fire

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    I use a 'boombox' portable radio in my garage and usually listen to either AM radio or sports broadcasts. I usually have some audible interference through the radio speakers when I have my 8' fluorescent strip lights on. I keep the radio plugged in to the outlet as it eats up batteries although my receptacle circuit is on a different breaker than my lighting circuits. Also I have both cold weather ballasts and non-cold weather ballasts and it does it on both. Is there any kind of grounding or antenna enhancements I can do to minimize this?

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  2. homebrewz

    homebrewz Minister of Fire

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    Sometimes the speaker wires or even the power cord of a radio can act as an antenna and pick up interference from other electronic devices in a room.
    You could try the following:

    - Keeping the speaker wires and power cable of the radio as short as possible and bunching up the slack
    - Plugging the lights into an outlet with a solid ground connection
    - Switching to a shielded speaker wire
    - Wrapping the slack of the speaker wires in a toroidal core.. its a type of interference filter.. basically a circular piece of iron which you
    wrap the speaker wire around and it helps filter out stray RF (radio frequency) signals from getting into the speaker wire. They're
    cheap and available at radio shack.

    The FM band antenna is the metal whip which extends out. The AM band antenna in a typical boom box is a ferrite bar wrapped with a thin copper wire. Its inside the radio. The only kind of antenna enhancement you could make would be to get one of the AM antenna boosters that sit near the radio, but try the other stuff first..
    A signal booster might boost the interference too. Probably the toroidal core is your best bet.

    cheers,
    bernd
  3. SlyFerret

    SlyFerret Minister of Fire

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    Not much you can do. Depending on how much troubleshooting you want to do, you might try disconnecting the wiring on each fixture one at a time to see if the noise goes away when one of the lights is off line. It's possible that one of your ballasts is noisy, and replacing the one unit would fix the interference. The ballasts on some inexpensive work lights are not serviceable, so the whole fixture would need replaced. Since you say it's an 8" fixture, it most likely doesn't fall into this group and has a replaceable ballast.

    -SF
  4. TMonter

    TMonter Minister of Fire

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    Are the ballasts in the lights magnetic or electronic? The magnetic ones cause the most interference.
  5. fbelec

    fbelec Minister of Fire

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    yah not much you can do with that radio, but try moving the radio itself in a 360 degree motion slowly you might find that there is a certain direction that works or makes the noise worse. if that doesn't work try laying the radio on it back and do the same thing. some of the electronic ballast make noise also but it is a different sound. if it still is bad the next time you see a garage sale and there is a old tube type radio pick it up. they usually have a place for a external antenna and use that with a coax cable to somewhere far away from the lights and hookup a wire at the end for a antenna. just connect to the center of the coax it should be fine.
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