Quick Question regarding splitters

Discussion in 'Playback Devices' started by Alexander Kuch, Apr 23, 2005.

  1. Alexander Kuch

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    I had someone ask me the other day if they use a 5-way splitter for example, and they only use 4 outs, that you need to cover the coax out jack that is not being used or it won't work. I don't use splitters, so I wouldn't know. Just wondering if anyone has heard anything like this.
     
  2. Jim Rakowiecki

    Jim Rakowiecki Stunt Coordinator

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    That's not true. If you have a four way splitter but only use three outputs it will work just fine.
    The biggest drawback is loss. Every splitter looses signal. A two way will lose 3.5 db, a three way will lose 5.5 db, a four way will lose 7.5 db, and a eight way will lose 12 db. It pays to match the splitter as closely as possible to the number of lines in use. Those losses will vary slightly between brands but not enough to matter.
    It is a good idea to terminate any open ports to prevent ingress or leakage and help maintain 75 ohms in the system.
    This should be done with a 75 ohm terminator covering it with piece of tape or a plastic cap won't make any difference.
     
  3. Alexander Kuch

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    Thanks Jim. That was pretty informative
     
  4. Rob*W

    Rob*W Auditioning

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    You are supposed to put some sort of terminating plug over the unused splits to prevent unwanted reflections.
     
  5. Seth Paxton

    Seth Paxton Lead Actor

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    Which, BTW, is done in all sorts of circuits. When I was still doing server motherboards for Compaq we had a signal specialist and all he did was check the various reflections and ensure that we had all our high speed lines terminated correctly.
     
  6. Bob McElfresh

    Bob McElfresh Producer

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    I have to agree about the reflection issue. This becomes a bigger problem with higher frequencies. (Think cable-modem signals being mixed with CATV signals).

    Radio Shack sells "50 ohm terminators" for less than $2 for a set. Your friend might notice ghosts that disappear if he uses the terminators.
     

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