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Thread: interference

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    Default interference

    hey guys
    question: i have the main foxtel box looped back into the fta dtv setup so i can watch fox in my room at night
    its always worked well but often i get like 2 horizontal bars with interference (poltergeist) that slowly scroll up or down the screen
    otherwise its bearable to watch

    is there any sort of filter i can put inline without much drama or cost
    to see if it fixes it.
    why do we need the NBN ? because the copper network is constipated & needs fibre



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    no takers?
    why do we need the NBN ? because the copper network is constipated & needs fibre

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    its known as a birdy !!! change frequency only way to get rid of it , there is no filter for it
    cheers don
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    Quote Originally Posted by hinekadon View Post
    its known as a birdy !!! change frequency only way to get rid of it , there is no filter for it
    cheers don
    thanks don
    ive had a few birdies in my life but i dont like this one
    being atv i guess theres no way to change frequency
    i have a av sender i could revert to, but im sure it was much the same.
    why do we need the NBN ? because the copper network is constipated & needs fibre

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    birdies are caused by two frequencys beating together and producing a third which shows up as a squark on the used frequency very common in old valve radios but not a thing of the past yet . Dont want to go into the production of harmonic mixing as its long and tedious cheers don
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    there used to be a setting in the installer menu to change rf output channel, maybe try that....

    setup button
    - 4 system setup
    - 4 system settings
    - at the next menu press 0611 and then select
    - 4 RF outlets

    alternatively try an aftermarket rf modulator or hdmi over lan works very well.....
    Last edited by hoe; 10-04-19 at 03:44 PM.



    Finally got FTTN, 710m line length....

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    Curious as to what analog TV channel you are using as a back channel?
    The symptoms you describe may be due to power line interference if the channel is in the VHF low band.
    Are there any coloured dots in the interference?
    Another cause of 100 Hz asynchronous bars can be mains hum induced by house wiring or any amplifiers in the system.
    Being as there is no FTA analog transmissions, the source can only be local. A poorly regulated PSU with a full wave bridge rectifier and failing capacitors can also introduce asynchronous hum.
    Don't rule out the TV itself being the cause of the issue.
    Sometimes a simple braid-breaker can help. A picture of the issue would be more than helpful.
    "Any sufficiently advanced technology is indistinguishable from magic."

    - Arthur C. Clarke

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    ill try that hoe

    im pretty sure its low band vhf, say you auto tune a tv in the house without a foxtel box, on atv, it finds it pretty quick, bit like old channel 3.
    last night it was fine, for what i remember, & i do have a powered inline amp hooked in straight after the foxbox, before it goes back into the system
    might try without it.
    why do we need the NBN ? because the copper network is constipated & needs fibre

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    Quote Originally Posted by hoe View Post
    there used to be a setting in the installer menu to change rf output channel, maybe try that....

    setup button
    - 4 system setup
    - 4 system settings
    - at the next menu press 0611 and then select
    - 4 RF outlets

    alternatively try an aftermarket rf modulator or hdmi over lan works very well.....
    found it hoe, any certain numbers? seems 4, 44, 41 i can find

    then retune my tv?
    why do we need the NBN ? because the copper network is constipated & needs fibre

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    Yes, change channel then rescan tv

    Sent from my CLT-L29 using Tapatalk



    Finally got FTTN, 710m line length....

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    twas the inline amp i have plugged in
    took it out, no lines
    why do we need the NBN ? because the copper network is constipated & needs fibre

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    theres very little difference between a oscillator and a amplifier the are basicly the same circuit , its easy to get a amp to oscillate and a oscillator to amplify when you dont design it properly. Glad you found it tho Don
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    Used to get these bars on the TV on my old analogue system on the UHF output of a decoder, as I ran it through an indoor antenna with "booster". Simply lowering the gain level used to get rid of the bars.

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    Quote Originally Posted by Dr_Mohs View Post
    Used to get these bars on the TV on my old analogue system on the UHF output of a decoder, as I ran it through an indoor antenna with "booster". Simply lowering the gain level used to get rid of the bars.

    yea i might put the amp back in, seems to have degraded my picture a bit
    it has gain control
    i wonder if swapping the coax on my bedroom run to sat cable rg6? would help.
    unsure what it is, but theres a old foxtel cable there from when i had my own box.
    why do we need the NBN ? because the copper network is constipated & needs fibre

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    Yeah better cable (preferably double-screened) and if possible new/better connectors (depending on interface) should generally help.

    Mine was on two 5 m long flyleads coupled together with the old standard type antenna/RF 75 Ohm connector. An F-type performs better, but of course it depends on the TV's interface, etc. which one you use.

    I used to lower the gain down from about 30 dB to 20 dB and the bars would disappear. If I lowered the gain more or removed the amp, the picture became snowy. This was on PAL I CCIR Ch. 46 (671.25 MHz).

    It's basically just a case of balancing the right amount of amplifier gain to make the picture clear but not so much that you end up with the bars. Maybe even try this just on its own before replacing cable or anything.
    Last edited by Dr_Mohs; 16-04-19 at 05:01 AM.

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    if you want to get better use rg11 and compression fittings ,the output is getting into the input of your amp by removing it this dont occur so when you put it back it restarts if theres not enough shielding in the amp - reducing the gain of the amp will make it seem to not be there but it is !!!the symptoms will just get used up in the losses so you wont see it if you are using rg59 sorry misses the boat rg6 a little better if its twin shielded ok . If you can get into the guts of the amp and solder some shields around the input all the better . I have found some of the cheapest/ nastiest amps will perform well if the input and outputs are well isolated cheers don
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