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Thread: interference on cat 5

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    Cool interference on cat 5

    This is a problem experienced by an associate that he asked me to explain., what are your thoughts.

    He has lately moved away from coax for CCTV & is only running cat 5 & baluns & uses switch mode power supplies. He says he is often getting some sort of interference ( no description ) which dissappears when he runs the power over fig 8 instead of over the cat 5. If he uses a xformer type power supply over the cat 5 the interferrence also dissappears. I am not a fan of switch mode power supplies & I suggeted that it is this in combination of the balun in close proimity of the power supply that is the cause of the problem. It is only an educated guess & without a bit of lab gear is the best I could offer. What do you think ?



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    what sort of baluns is he using.

    I think i have said this in teh past, but if you use the NVT brand ones the problems you will get are very minimal.

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    Why use baluns and not coax?

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    Cool

    Quote Originally Posted by keef82 View Post
    Why use baluns and not coax?
    That is what I said to him

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    So the powersupply is at the DVR end with the twin running to the camera?
    If thats the case, switchmodes usually have a reference to earth, so there is probably an earth-loop with the camera being earthed in it's location, plus the reference to earth at the PSU end. Transformer type outputs are isolated from earth, kinda defeats the use of a balun, problem would likely not exist if the PSU were at the camera end.

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