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OTA signal weakening with multiple TVs

Discussion in 'Local Reception' started by golfer29, Oct 8, 2009.

  1. Oct 8, 2009 #1 of 12
    golfer29

    golfer29 New Member

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    I've tried to search but could not find a specific answer.

    My OTA reception is fine when I use one TV. When I try to use a good 2 way splitter, the signal becomes much weaker, even when I don't hook up the second TV.

    Do I need a preamp? Can I buy a preamp/splitter in one unit or do I need both a preamp and a splitter?

    I have one cable coming into the house from the antenna and would like to split it into 4 once it's in the house. I have electric power at that location if needed.

    What is the best equipment to use to split my OTA signal into 4?
     
  2. Oct 8, 2009 #2 of 12
    Stuart Sweet

    Stuart Sweet The Shadow Knows!

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    Do you have anything to measure signal strength, like a signal meter on a DIRECTV AM21 or built-in to the TV? It seems like your signal is marginal and splitting it just takes it down to the point where it's unusable.

    I've heard differing opinions about using a preamp with digital TV. Some feel that it just amplifies the noise along with the signal. Perhaps reaiming the antenna would be a first step.
     
  3. Oct 8, 2009 #3 of 12
    Nick

    Nick Retired, part-time PITA DBSTalk Club

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    The...
    Get a distribution amp (powered splitter) -- no problem with amplifying noise from digital OTA.
     
  4. Oct 8, 2009 #4 of 12
    golfer29

    golfer29 New Member

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    Sep 25, 2009
  5. Oct 8, 2009 #5 of 12
    lflorack

    lflorack Godfather

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    It's my understanding that splitting the signal in two results is a 50% drop in signal strength (3db). Additional splits cause further signal degradation to each output. If you have a marginal signal coming into the house from the antenna, splitting it will have an obvious effect. To answer your question, splitting your incoming signal affects the available signal strength even when nothing is connected or on. So, for example, if you only need a two-way splitter, don't use a 4-way splitter because you're losing more signal strength at each output than you need to.

    Key things to consider:
    • Ensure your antenna is properly aimed for maximum signal
    • Make sure your cables -- both from the antenna and from the splitter to the TV's or receivers, etc -- are as short as possible and have as few (if any) splices as possible -- and are of good quality
    • Use a good quality splitter with the minimum number of outputs as possible to fill your needs. More splits means less available signal for each output. Also, make sure that it's high a frequency type 50-2050 mhz for digital reception.

    Once you do all of the above, you may find that the signal strengths to each TV (or whatever) is too weak. You can then consider:
    • a better location for your antenna
    • a better antenna for your situation
    • a preamp

    I have just a two-way splitter in my antenna wiring and I use a preamp with my antenna (see my System Diagram via the link below) and it works fine. It must be mounted prior to any splitting to gain the benefit for each TV.

    Good luck!
     
  6. Oct 8, 2009 #6 of 12
    Stewart Vernon

    Stewart Vernon Roving Reporter Staff Member Super Moderator DBSTalk Club

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    Even without the technical details... each split = 50% signal loss because you split the signal.

    IF you have a good strong signal to begin with, then as others have suggested a good pre-amp will be able to boost your signal and make your splits still good... but you will need a good signal to begin with. Amplifying a bad signal will amplify the bad as well and might not help.

    So... antenna placement/tuning to get the best signal first is recommended... then get an amp and splitters and see what happens.
     
  7. Oct 8, 2009 #7 of 12
    CCarncross

    CCarncross Hall Of Fame

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    Silly question, I thought the typical drop per leg was 3.5dB? Am I remembering that wrong?
     
  8. Oct 9, 2009 #8 of 12
    Scott in FL

    Scott in FL Godfather

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    A two way splitter has about 3.5 dB loss. Theoretically it is 3 dB, but nothing is 100% efficient. The extra 0.5 dB is due loss within the splitter.

    The equation for calculating theoretical loss is:

    10 log Power Ratio = loss or gain in dB.

    So splitting the signal in two is:

    10 log 1/2 = 3 dB

    Splitting three ways:

    10 log 1/3 = 4.77 dB

    etc.
     
  9. Oct 9, 2009 #9 of 12
    jkane

    jkane Icon

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    Yep! This is the reason amps were created. They don't work well on weak signals to start with, but if you have a good signal and need to split it, then an amp is the answer. Get one with multiple outputs and you are all set.
     
  10. no static at all

    no static at all Cool Member

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    Jan 17, 2009
  11. SayWhat?

    SayWhat? Know Nothing

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    If you want to boost the signal coming in to the house, use a mast-mounted signal pre-amp.

    If you were to only need 3 of the 4 outlets of the distribution amp for some reason, terminate the unused port with a 75 ohm dummy load available from any store that deals in TV antennas and cables. They only cost a buck or so each.
     
  12. golfer29

    golfer29 New Member

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    Sep 25, 2009
    Thanks, the signal is fine on one TV. I will look into getting this one
     

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