Power supply interference

Discussion in 'Computer Support' started by jll, Jan 17, 2004.

  1. jll

    jll Guest

    Hi,
    Recently, I installed a new 400 watt power supply. Now I get interference on
    my AM radio stations. Is there some gizmo I can buy say at a place like
    Radio Shack to stop this?
    Thanks,
    jll
    address is fake
     
    jll, Jan 17, 2004
    #1
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  2. jll

    Jerry G. Guest

    The IF amplifier in your AM radio is at 455 kHz. The switching power supply
    speed is at about 45 kHz which is a near sub harmonic of the IF amp in the
    AM radio. Since the power supply drive is of very rapid square wave pulses
    that are duty cycled, these produce a lot of harmonics.

    Very often these power supplies will cause AM radio interference.

    --

    Greetings,

    Jerry Greenberg GLG Technologies GLG
    =========================================
    WebPage http://www.zoom-one.com
    Electronics http://www.zoom-one.com/electron.htm
    =========================================


    "jll" <> wrote in message
    news:YE%Nb.71213$sv6.148391@attbi_s52...
    Hi,
    Recently, I installed a new 400 watt power supply. Now I get interference on
    my AM radio stations. Is there some gizmo I can buy say at a place like
    Radio Shack to stop this?
    Thanks,
    jll
    address is fake
     
    Jerry G., Jan 17, 2004
    #2
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  3. jll

    Sano Guest

    So it's a cheap-ass power supply?

    Fix your sig please. It goes at the Bottom of your post, not the middle.

    "Jerry G." <> spluttered in
    news:buaag8$dpt$:

    > The IF amplifier in your AM radio is at 455 kHz. The switching power
    > supply speed is at about 45 kHz which is a near sub harmonic of the
    > IF amp in the AM radio. Since the power supply drive is of very
    > rapid square wave pulses that are duty cycled, these produce a lot of
    > harmonics.
    >
    > Very often these power supplies will cause AM radio interference.


    <crap sig>

    "jll" <> wrote in message
    news:YE%Nb.71213$sv6.148391@attbi_s52...
    Hi,
    Recently, I installed a new 400 watt power supply. Now I get interference
    on
    my AM radio stations. Is there some gizmo I can buy say at a place like
    Radio Shack to stop this?



    --
    "The true man wants two things: danger and play.
    For that reason he wants woman, as the most
    dangerous plaything." - Friedrich Nietzsche
     
    Sano, Jan 17, 2004
    #3
  4. Sano wrote:

    > So it's a cheap-ass power supply?


    Yup - I agree... Cheap unit = unsafe

    > "Jerry G." <> spluttered in
    > news:buaag8$dpt$:
    >
    >>The IF amplifier in your AM radio is at 455 kHz. The switching power
    >>supply speed is at about 45 kHz which is a near sub harmonic of the
    >>IF amp in the AM radio. Since the power supply drive is of very
    >>rapid square wave pulses that are duty cycled, these produce a lot of
    >>harmonics.
    >>Very often these power supplies will cause AM radio interference.


    (Blink) uhh... regardless if the IF or the rectifier bridge (I think
    your calculations are off, btw), it shoulnd be happening in the frist
    place - FCC regs and all, y'know.

    > "jll" <> wrote in message
    > news:YE%Nb.71213$sv6.148391@attbi_s52...
    > Hi,
    > Recently, I installed a new 400 watt power supply. Now I get interference
    > on my AM radio stations. Is there some gizmo I can buy say at a place like
    > Radio Shack to stop this?


    Do yourself a favor - dump that supply ang get another. This shouln't be
    happening, period - properly made PS's have filtering already built in
    to stop this, like I mentioned, because the're supposed to.

    --
    --

    BuffNET Technical Support Supervisor
    (BEHOLD! The power of the BOFH!)
     
    BuffNET Tech Support - MichaelJ, Jan 17, 2004
    #4
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