Results 1 to 11 of 11

Thread: mains filter

  1. #1
    Junior Member
    Join Date
    Jan 2008
    Posts
    19
    Thanks
    7
    Thanked 0 Times in 0 Posts
    Rep Power
    0
    Reputation
    10

    Question mains filter

    Hi guys,
    My digital box suffers from freezes and the occasional pops. 99% of this is caused from light switches being turned on/off, ceiling fan switches etc. Basically when anything is turned on or off in the house. I've tried a cheapy power board with a AC filter in it but didn't change anything. I was hunting around and found this:
    Just wondering if anyone has tried one of these, or has any other ideas.

    Thanks, Jason



Look Here ->
  • #2
    Senior Member
    Uncle Fester's Avatar
    Join Date
    Jan 2008
    Location
    Commonly found in a pantry or the bottom of a fridge, searching for grains, fermented or distilled
    Posts
    6,405
    Thanks
    2,289
    Thanked 4,414 Times in 2,517 Posts
    Rep Power
    2046
    Reputation
    81778

    Default

    I have probably used over a 100 digital and analogue boxes and other 'sensitive' electronic equipment of some kind but never had a problem when I switched lights or ceiling fans.

    I would suspect a faulty box.... unless you are running from an inverter

  • #3
    Junior Member eastlake's Avatar
    Join Date
    Feb 2008
    Location
    In the vertical interval
    Posts
    67
    Thanks
    1
    Thanked 0 Times in 0 Posts
    Rep Power
    198
    Reputation
    10

    Default

    It could also be that your received signal or signal to noise ratio is marginal, and when you switch lights etc, on or off the quick burst of RF is causing the receivers decoder to drop out.
    Common sense isn't !!!

  • #4
    Senior Member
    Join Date
    Jan 2008
    Posts
    568
    Thanks
    39
    Thanked 51 Times in 27 Posts
    Rep Power
    220
    Reputation
    201

    Default

    The noise spikes are probably getting into the digital receiver via the antenna and its coax feeder. Analogue TV usually shows this a flash of white on a dark picture, digital TV shows it as a loss of MPEG data where the picture stalls momentarily, sometimes accompanied by a short screech heard in the audio.

    You can help minimise this effect by the use of better coax (RG6Q as used for satellite installations is excellent), but if your TV signal at the antenna is weak the noise pulses can be strong enough to get into the system through the antenna. The only way to remedy this is to kill the noise pulses at the source which means fitting mains noise suppression devices on the 240VAC mains at the noise source, or move the antenna itself away from the noise. Coax cable runs must be kept away from mains wiring.

    Refrigerator and freezer thermostats are the worst offenders at my location, and I use a cheap power board with built-in noise suppression to cure most of the switching noise. Some digital receivers are better than others in regard to noise immunity, and recover more quickly. My Panasonic HDD/DVD recorder seems to have some kind of audio mute as the MPEG screech is nowhere as bad as it is from my Wintal HDD box.

  • #5
    Junior Member
    Join Date
    Jan 2008
    Posts
    19
    Thanks
    7
    Thanked 0 Times in 0 Posts
    Rep Power
    0
    Reputation
    10

    Default

    Thanks for the replies. I've got a good digital antenna, with quad sheild coax and f-connectors/splitters and i get excellent reception. The house is old, approx 50 years, so maybe it's the old wiring. I'm tossing up between the mains filter i posted earlier or one of these:

    It's one of those things, if i knew it would definitely fix it i would buy one straight away, but i don't want to waste the money if it's not going to work

  • #6
    Senior Member
    Join Date
    Jan 2008
    Posts
    568
    Thanks
    39
    Thanked 51 Times in 27 Posts
    Rep Power
    220
    Reputation
    201

    Default

    If the noise spikes are from refrigerators/freezers etc., it's no good having the filters at the TV, these spikes need to be suppressed at their source.

    The noise is generated at the thermostat contacts therefore you need suppression as close as possible to the contacts as the noise is radiated by the mains wiring and the appliance lead.

    In years past you could buy 240V plugs with a suppression capacitor built in, but I have not seen them recently. If you could find such an item it could be installed on the mains leads which should be cut as short as practicable.

  • #7
    Premium Member
    Join Date
    Jan 2008
    Location
    Melbourne
    Posts
    854
    Thanks
    246
    Thanked 87 Times in 69 Posts
    Rep Power
    243
    Reputation
    886

    Default

    I have the exact same problem,.. worst culprits are the washing machine and hair dryer, but lights also set it off.

    Oddly enough, I even get it from that lighter/sparky thing you buy at the $2 shop to light the gas cooktop.

    I'm lead to believe that a properly installed antenna will resolve your issue, i.e. you need to get a quality signal in at the source to overcome the interference that may be present at your location.

    I'll be needing to call on an antenna installer when I'm fed up with it as I can't be bothered trying a 3rd location,.. I believe I may need to go upwards at my place.

    Jim.....

  • #8
    Senior Member
    Uncle Fester's Avatar
    Join Date
    Jan 2008
    Location
    Commonly found in a pantry or the bottom of a fridge, searching for grains, fermented or distilled
    Posts
    6,405
    Thanks
    2,289
    Thanked 4,414 Times in 2,517 Posts
    Rep Power
    2046
    Reputation
    81778

    Default

    I slightly misinterpreted your first post as I thought the box would freeze like you needed to power down to reset it or something.
    Indeed, old antenna wiring running possibly parallel with the lighting circuit can cause disturbances to the digital input signal and create short drop outs.
    Plugging the box through an AC mains filter will hardly help.

    If you can climb into the roof cavity you might be able to move the antenna cable and mains cable further away from each other.

  • #9
    Junior Member eastlake's Avatar
    Join Date
    Feb 2008
    Location
    In the vertical interval
    Posts
    67
    Thanks
    1
    Thanked 0 Times in 0 Posts
    Rep Power
    198
    Reputation
    10

    Default

    A simple but effective way to suppress the spikes at the equipment that is causing them, is to use ferrite rods and wrap as many turns of the AC supply lead as you can around the ferrite rod, as close to the piece of gear as you can.
    Then hold it in place with some electrical tape, this forms an RF choke on the supply lead and should attenuate the spikes considerably. You can rat the rods out of old AM radios or buy them at electronics suppliers. Generally they are cheap, so this might be an inexpensive fix for you.
    Common sense isn't !!!

  • #10
    Junior Member
    Join Date
    Jan 2008
    Posts
    19
    Thanks
    7
    Thanked 0 Times in 0 Posts
    Rep Power
    0
    Reputation
    10

    Default

    Quote Originally Posted by eastlake View Post
    A simple but effective way to suppress the spikes at the equipment that is causing them, is to use ferrite rods and wrap as many turns of the AC supply lead as you can around the ferrite rod, as close to the piece of gear as you can.
    Then hold it in place with some electrical tape, this forms an RF choke on the supply lead and should attenuate the spikes considerably. You can rat the rods out of old AM radios or buy them at electronics suppliers. Generally they are cheap, so this might be an inexpensive fix for you.
    Thanks for the suggestion, i have some that i forgot all about, will try to find them.

  • #11
    Senior Member
    best4less's Avatar
    Join Date
    Jan 2008
    Location
    Australia
    Posts
    7,684
    Thanks
    3,487
    Thanked 2,207 Times in 1,132 Posts
    Rep Power
    757
    Reputation
    15165

    Default

    Quote Originally Posted by eastlake View Post
    A simple but effective way to suppress the spikes at the equipment that is causing them, is to use ferrite rods and wrap as many turns of the AC supply lead as you can around the ferrite rod, as close to the piece of gear as you can.
    Then hold it in place with some electrical tape, this forms an RF choke on the supply lead and should attenuate the spikes considerably. You can rat the rods out of old AM radios or buy them at electronics suppliers. Generally they are cheap, so this might be an inexpensive fix for you.

    Done this a many times for the old people who like to listen
    to the am radio and it makes a huge improvement
    When you do things right, people won't be sure that you have done anything at all

  • Bookmarks

    Posting Permissions

    • You may not post new threads
    • You may not post replies
    • You may not post attachments
    • You may not edit your posts
    •