radio station interference in the phone

Discussion in 'NZ Computing' started by Guest, Sep 14, 2013.

  1. Guest

    Guest Guest

    My neighbour has a "landline phone" she recently bought that she can
    hear music from a nearby radio station in the receiver all the time.
    If we switch to a phone that is powered from a DC plug pack, there's
    no music in the phone. I think she wants to have a phone that works
    even when there's a power fail.

    Has anyone ever heard of this or know what can be done about it?

    The previous phone she had was also a landline but she accidentally
    damaged the phone socket on the wall so an electrician came and fixed
    up the wall socket but after that, the phone wouldn't ring any more
    for incoming calls. So she bought a new phone, but now she gets
    unwanted background music. The music stops when the radio station
    (radio Ferrymead) stops broadcasting!
     
    Guest, Sep 14, 2013
    #1
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  2. Guest

    Malcolm Guest

    Hi
    Yes, it use to occur in Titahi Bay Wellington.

    Is it a certified phone as in the PTC label fitted?

    If it doesn't ring then the electrician has either used a secondary
    block, rather than a primary with the capacitor and resistor fitted.
    Unless the one repaired was a secondary block, then it's been wired
    incorrectly. Primary block is incoming line to 2 and 5, then 2,3 and 5
    to the secondary block(s).
     
    Malcolm, Sep 14, 2013
    #2
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  3. Ferrite Rings looped around the phone line will stop that..
     
    Frank Williams, Sep 14, 2013
    #3

  4. Most new Phones are only 2 wire, the Ring connection was meant for pulse
    dialing, they then clamped the ring line to stop the other phones
    ringing when you dialed out.

    Not needed on modern phones as they don't have pulse dialing.
     
    Frank Williams, Sep 14, 2013
    #4
  5. Guest

    Guest Guest

    What sort and whereabouts do you put them?
     
    Guest, Sep 14, 2013
    #5

  6. I used the Large Ring type blue gray coated came from some EX gear,
    Jaycar dose not list them and Wiseman use to sell them.

    The now seem to use the clamp on type, you might have then fitted to
    some power cards or USB lead, so you could remove one and try it, some
    you loop the cable through it and some just clamp over the cable.

    Jaycar does list some clamp types.

    Try removing one from a USB/Power cable a a test to see if it works.

    This would be fitted to the phone cable at the wall end, and may be also
    at the phone end.


    Some links

    http://en.wikipedia.org/wiki/Ferrite_bead


    http://audiosystemsgroup.com/SAC0305Ferrites.pdf
    http://nz.mouser.com/search/refine.aspx?Ntk=P_MarCom&Ntt=116549093

    http://nz.mouser.com/Search/Refine.aspx?Keyword=clamp+on+ferrite+bead


    http://popular.ebay.com/business-industrial-d-j/emi-ferrite.htm

    http://www.moddiy.com/products/TDK-...-&-Ferrites-Round-7mm-Cable-Clamp-Filter.html

    http://www.epcos.com/web/generator/Web/Sections/Components/Page,locale=en,r=247996,a=2197068.html

    All types

    https://www.google.co.nz/search?q=c...v&sa=X&ei=f1E1Ut-SJ4aciQfU_4DQCg&ved=0CHcQsAQ
     
    Frank Williams, Sep 15, 2013
    #6
  7. Guest

    Guest Guest

    ok, thanks.
     
    Guest, Sep 15, 2013
    #7
  8. Guest

    Richard Guest

    Current sockets used will have a 2C on the front, and lack any ring
    capacitor in them since it has been a very very long time since phones
    were made which needed them.

    For the OP, try a ADSL filter to get rid of the RF on the phoneline.
    Dirt cheap and a simple plugin device.
     
    Richard, Sep 18, 2013
    #8
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