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Interference from digital set top box

Discussion in 'Hobby Electronics' started by Mac, Aug 30, 2007.

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  1. Mac

    Mac Guest

    Hi All,

    As some of you may know I had a high noise level which appeared intermittant
    at first then solid.
    Of recent times it has been a solid S9 on 80mx and S8 on 40mx day and
    night.I guess the intermittant
    part was the 11kv power lines out the front so one would think that will
    continue from time to time.
    In the finish, I tracked the solid interference down to a standard
    definition set top digital TV box which was
    in idle mode 24/7. Even when I disconnected the TV aerial leads (in/out) it
    didn't change. I tried winding
    the power lead on a ferrite bar and eventually the TV coax but no effect.
    The plug pack is not a switching supply
    either. It just plain seems the plastic cased unit radiates broadband
    interference and doesn't need an aerial either.

    The brand is a "KROSS" Model "DSK530STB" and I would be interested if the
    same problem is noted with other
    brands or models.

    My noise level has dropped to S4-5 80mx (daytime) and S2-3 40mx. Big
    difference to my ears.

    Would be a shame if one of my neighbours bought one!!!!

    73 de Peter

    ----------------------------------------------------------------------------------
    Mid North Coast Amateur Radio Group Inc.
    Coffs Harbour And District Amateur Radio Club Inc.
    CW Operator's QRP Club Inc. No. #563
    Wireless Institute Of Australia.
    International Fox Tango Club.
    ----------------------------------------------------------------------------------
     
  2. Guest

    Guest Guest

    It costs too much to have C tick compliance, that would eat into the profits
    on their 10 containers of the spugie emitting ebay rubbish.
    Build a faraday cage for it.

    Rob
     
  3. Mac

    Mac Guest

    Hello chaps,

    This Kross STB was purchased from Woolworth Supermarket, Park Avenue Coffs
    Harbour an is supposed to be
    complient with Australian regulations.

    Cya Mac
     
  4. Mr.T

    Mr.T Guest

    And the key word is "supposed", until some one complains very loudly indeed,
    the authorities do not check that actual shipments comply with any
    regulations.
    Until companies are comprehensively fined, it is usually cheaper for them to
    ignore such regulations.

    MrT.
     
  5. who knows

    who knows Guest

    It depends on who holds the registration - many devices are identical but
    simply "badge-engineered" for different suppliers.

    The required response is clear:

    1. contact the supplier and make noises about interference, suspected
    non-compliance etc,

    2. contact the ACMA area office, lodge a formal complaint (make noises
    about suspect non-compliance or suspect labelling) - either pay your $60 or
    get your neighbours to also complain.

    Keith G Malcolm
    VK1ZKM
    3 September 2007
     
  6. Wayne Reid

    Wayne Reid Guest

    Hey Mac, are you sure the plug pack is not a switchmode PSU? The broadband
    radiation you describe would seem to be more likely to eminate from a faulty
    switchmode. I had a Kross STB, but I gave it to my Mum when the Thompson
    unit she had suffered a failed PSU, which radiated in a similar way that you
    described. She couldn't pick up any AM radio due to the interference.
    Unplugging the Thompson fixed it.

    I recall that the PSU on the Kross was very lightweight, so I assumed it to
    be a switchmode. I didn't crack it open to find out though :)

    I eventually hooked up a conventional 12v DC regulated transformer wall wart
    to the Thompson, and it now works, although it does need to be unplugged
    every now and then when it locks up.

    The Kross is still going OK. I recall that it used to squeel and break up
    when a certain light switch was turned on or off. I reduced the affect by
    winding the power lead onto a ferrite core.


    WR
     
  7. Mac

    Mac Guest

    Oh Bugger!!! it was a switch mode plug pack supply and thats where all the
    hash came from. Used a linear supply and all clear.

    Cya Peter
     
  8. Roj Blake

    Roj Blake Guest

    I got caught out too with a switch mode from Jaycar, noise o plenty!
     
  9. Wayne Reid

    Wayne Reid Guest

    Thought so.
     
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