UPS and radio interference

Discussion in 'Computer Information' started by - Bobb -, Sep 10, 2007.

  1. - Bobb -

    - Bobb - Guest

    I have a few APC UPS's including one for stereo equipment and one for
    computer. When I turn on PC, I hear whine when listening to AM signal of
    tuner . I would think between the 2 UPS's I should get NO interference.
    1. Am I maybe getting the whine " through the air" vs "thru the electrical
    system" ?
    2. How to tell ?
    3. Wherever its source, how to stop it ?
    Thanks

    PS - whine not noticeable in lower AM range , but if on 1030AM ( and
    higher frequencies) it's a steady high-pitched noise in addition to the
    radio audio.
    - Bobb -, Sep 10, 2007
    #1
    1. Advertising

  2. - Bobb -

    Paul Guest

    - Bobb - wrote:
    > I have a few APC UPS's including one for stereo equipment and one for
    > computer. When I turn on PC, I hear whine when listening to AM signal of
    > tuner . I would think between the 2 UPS's I should get NO interference.
    > 1. Am I maybe getting the whine " through the air" vs "thru the
    > electrical system" ?
    > 2. How to tell ?
    > 3. Wherever its source, how to stop it ?
    > Thanks
    >
    > PS - whine not noticeable in lower AM range , but if on 1030AM ( and
    > higher frequencies) it's a steady high-pitched noise in addition to the
    > radio audio.
    >


    Whether the UPS can cause a whine, will first depend on the architecture.
    I have an SPS for example, the cheapest kind, and the inverter in one
    of those does not operate, until the power fails. That one is not a
    line interactive model.

    There may be other kinds, that the inverter runs all the time, and that
    could be what you are hearing.

    I would say the most likely mechanism, is conducted emissions. Meaning
    the noise is delivered on the cable, and not through the air.

    And that is not all - if the noise is on the cable, the cable can function
    as an antenna, and then the signal is also spilled into the air.

    This is an example of a "filter brick". If placed on the input side
    to the UPS, it would prevent noise from going back into your wall plug.
    If place on the output side, it would prevent non-60Hz energy from
    going to the load. Ideally, you want to buy these at some place that
    doesn't charge a premium, as they can be expensive if you aren't
    careful where you buy them. Newark sells them, but would not be the
    cheapest place.

    http://www.cor.com/PDF/N.pdf

    Ouch - Digikey wants $92 for one!
    http://www.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=CCM1649-ND

    The single stage is cheaper, but still not what I want to see.
    http://www.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=CCM1713-ND

    Filters like that, are present on premium outlet strips. But perhaps
    not dual stage filters, like the 10VN1 example. And since the 10VN1
    is being sold as an electrical component, it still needs cords and
    plugs fitted, and a housing around it to prevent electrocution
    of the unsuspecting.

    "filter banks" - but no attenuation specs.
    http://www.tripplite.com/products/product.cfm?productID=1347

    My partial solution to this problem, it to put an antenna in a distant
    part of the house, far away from the computer room. I do that for
    OTA broadcast video. I have an antenna, a 300 ohm to 75 ohm balun,
    a 20dB amplifier, maybe 75 feet of coax, and then a distribution
    box in the computer room. By doing that, the TV antenna picks up
    less interference from computers and related stuff. If I use an
    antenna locally, I'll see herringbone patterns from my Antec power
    supply :)

    What I cannot tell you, is how best to "remote" A.M. pickup. There
    are web pages that discuss building antennas, and maybe the
    directional nature of one of these would help.

    http://www.mindspring.com/~loop_antenna/

    Paul
    Paul, Sep 10, 2007
    #2
    1. Advertising

  3. - Bobb -

    - Bobb - Guest

    "Paul" <> wrote in message news:fc4020$40c$...
    >- Bobb - wrote:
    >> I have a few APC UPS's including one for stereo equipment and one for
    >> computer. When I turn on PC, I hear whine when listening to AM signal
    >> of tuner . I would think between the 2 UPS's I should get NO
    >> interference.
    >> 1. Am I maybe getting the whine " through the air" vs "thru the
    >> electrical system" ?
    >> 2. How to tell ?
    >> 3. Wherever its source, how to stop it ?
    >> Thanks
    >>
    >> PS - whine not noticeable in lower AM range , but if on 1030AM ( and
    >> higher frequencies) it's a steady high-pitched noise in addition to the
    >> radio audio.
    >>

    >
    > Whether the UPS can cause a whine, will first depend on the
    > architecture.

    << Snipped to clarify this one point >>

    I don't suspect the APC 350VA UPS to be the CAUSE. With no UPS's same
    issue. It seems the PC is the CAUSE. With PC off (on its UPS in den) the
    radio ( on a different APC 350VA UPS in LR) AND the radio ( on a third APC
    350VA UPS in Bedroom) is fine.

    Whatever the reason for the whine, I thought the UPS's would
    isolate/filter it. Same thing still.
    BTW I DO have a TV card/coax attached to the PC. Maybe THAT is the reason
    ( as you say - acting as antenna) ?
    - Bobb -, Sep 10, 2007
    #3
  4. - Bobb -

    Paul Guest

    - Bobb - wrote:
    >
    > "Paul" <> wrote in message news:fc4020$40c$...
    >> - Bobb - wrote:
    >>> I have a few APC UPS's including one for stereo equipment and one for
    >>> computer. When I turn on PC, I hear whine when listening to AM signal
    >>> of tuner . I would think between the 2 UPS's I should get NO
    >>> interference.
    >>> 1. Am I maybe getting the whine " through the air" vs "thru the
    >>> electrical system" ?
    >>> 2. How to tell ?
    >>> 3. Wherever its source, how to stop it ?
    >>> Thanks
    >>>
    >>> PS - whine not noticeable in lower AM range , but if on 1030AM ( and
    >>> higher frequencies) it's a steady high-pitched noise in addition to
    >>> the radio audio.
    >>>

    >>
    >> Whether the UPS can cause a whine, will first depend on the architecture.

    > << Snipped to clarify this one point >>
    >
    > I don't suspect the APC 350VA UPS to be the CAUSE. With no UPS's same
    > issue. It seems the PC is the CAUSE. With PC off (on its UPS in den) the
    > radio ( on a different APC 350VA UPS in LR) AND the radio ( on a third
    > APC 350VA UPS in Bedroom) is fine.
    >
    > Whatever the reason for the whine, I thought the UPS's would
    > isolate/filter it. Same thing still.
    > BTW I DO have a TV card/coax attached to the PC. Maybe THAT is the
    > reason ( as you say - acting as antenna) ?
    >


    I don't see a reason to suspect the TV card. But if you wish, you can try
    disconnecting the coax to the TV card, then see if your AM radio is
    affected or not.

    I believe you, when you say the problem disappears when the PC is powered
    off. Since I've seen my Antec power supply, put a herringbone pattern on
    my TV screen, I know that an ATX power supply can do it. I'm just surprised
    that FCC rules don't apply to them. If I had to fix it, I'd want to try
    something like the 10VN1. To me, it looks like a conducted emissions problem,
    with switching noise flowing backwards on the PC's power cable. Placing a
    filter as close as possible to the PC (i.e. use as short an AC cable between
    the filter device and the computer), will reduce the loop size of the antenna.
    Which is why, the filter should be inside the PSU...

    The UPS could have a filter in it, but I doubt they provide a spec for its
    effectiveness. The filter could be present, to help the UPS itself meet
    FCC.

    Paul
    Paul, Sep 11, 2007
    #4
  5. - Bobb -

    w_tom Guest

    On Sep 10, 4:43 pm, "- Bobb -" <b...@noemail.123> wrote:
    > I don't suspect the APC 350VA UPS to be the CAUSE. With no UPS's same
    > issue. It seems the PC is the CAUSE. With PC off (on its UPS in den) the
    > radio ( on a different APC 350VA UPS in LR) AND the radio ( on a third APC
    > 350VA UPS in Bedroom) is fine.
    >
    > Whatever the reason for the whine, I thought the UPS's would
    > isolate/filter it. Same thing still.


    Noise on an AM (medium wave) radio suggests bad computer hardware.
    Often due to power supplies that are missing essential functions. But
    other defective components (common in clone system built on price by
    someone without electrical knowledge) inside the computer can also
    cause that noise.

    Remember, component manufactures need do no effort to restrict that
    noise. Noise reduction is the responsibility of the computer
    assembler. The guy who so often does not know how electricity works
    even if A+ Certified.

    You are fooling yourself if you think a typical UPS provides any
    filtering or isolation. Does it claim that function in numbers? So
    many computer assemblers who don't even know how electricity works
    will promote myths about UPS functions.

    View it yourself. Review those APC numeric specs. Numerous claims
    can be made in color glossy sales brochures. Only place those claims
    matter are in numeric specs. Where do those specs make claims to
    provide filtering and isolation? They do not.

    Meanwhile, what is the dirtiest electricity delivered to that
    stereo, et al? When a UPS is in battery backup mode, then electricity
    will often be the dirtiest. AC mains never provide electricity that
    dirty. Electricity so dirty that it may even harm some small electric
    motors. But again, did you learn about UPSes from popular myths - or
    learn using science. Science starts with numeric specifications.

    Remember, a UPS typically dumped into the market as cheap as
    possible. Even a car battery that remains outside in adverse weather
    will last twice as long as the rarely used battery inside a UPS.
    Don't make assumptions for what that UPS does. It does one thing -
    provide electricity during blackouts and extreme brownouts - nothing
    more.
    w_tom, Sep 11, 2007
    #5
    1. Advertising

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

It takes just 2 minutes to sign up (and it's free!). Just click the sign up button to choose a username and then you can ask your own questions on the forum.
Similar Threads
  1. Andy Petro

    Radio interference

    Andy Petro, Dec 10, 2003, in forum: Computer Support
    Replies:
    8
    Views:
    3,721
    smehta82
    Aug 29, 2010
  2. Doug
    Replies:
    9
    Views:
    21,857
    boywonder
    May 16, 2004
  3. LEO THOMPSON

    Radio interference

    LEO THOMPSON, Feb 13, 2004, in forum: Computer Information
    Replies:
    6
    Views:
    718
    LEO THOMPSON
    Feb 14, 2004
  4. smehta82
    Replies:
    0
    Views:
    1,357
    smehta82
    Sep 5, 2010
  5. nospam

    radio station interference in the phone

    nospam, Sep 14, 2013, in forum: NZ Computing
    Replies:
    7
    Views:
    321
    Richard
    Sep 18, 2013
Loading...

Share This Page