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How a splitter works

Discussion in 'DIRECTV Connected Home' started by veryoldschool, Nov 18, 2010.

  1. veryoldschool

    veryoldschool Lifetime Achiever Staff Member Super Moderator DBSTalk Club

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    Seems like this needs a bump from last year:

    [​IMG]
    [​IMG]


    Now the green labeled have another part to them for DECA.
    On the back side of the board is a filtered resistor circuit that bridges the DECA signal between the outputs
    The loss is:
    2-way = 8 dB
    4-way = 11 dB
    8-way = 14 dB

    Without this added circuit the DECA loss would be the same as the isolation which is about 22 dB minimum.
     
  2. Sim-X

    Sim-X Godfather

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    Thanks
     
  3. hdtvfan0001

    hdtvfan0001 Well-Known Member

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    I vote Sticky.
     
  4. bobnielsen

    bobnielsen Éminence grise

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    Bainbridge...
  5. veryoldschool

    veryoldschool Lifetime Achiever Staff Member Super Moderator DBSTalk Club

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    So to show what an 8-way looks like inside:

    [​IMG]

    I've colored in one path that ends with two outputs and show the actual layout to the right. You'll see three more resistors have been added. These are to increase the bandwidth/frequency range.
     
  6. veryoldschool

    veryoldschool Lifetime Achiever Staff Member Super Moderator DBSTalk Club

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    Since these are all made up from the basic 2-way, there is very little difference between using a 2-way to feed two 4-ways, or a 4-way to feed four 2-way, or using one 8-way.

    Why you might need to use a combination of these verses one, could be because there aren't enough coax to have home runs off the 8-way.

    With the SWiM, you have about 25-30 dB of both splitter + coax loss before the signal drops too low at the receiver, which should be about what you have with an 8-way and 175' of coax.
    Now if you have to use a 2-way at the receiver, and it's a long coax run, you could find you have problems using an 8-way to feed this.

    One 2-way has about the same loss as 50' of coax.
    One 4-way has about the same loss as a 2-way connected to another 2-way.
    One 8-way has about the same loss as a 2-way connected to a 2-way, connected to another 2-way. This leaves about 150'-175' of coax loss between the SWiM and the receiver.
    If you have to use more than 3 2-ways in line, then you need to have about 50' shorter coax for each added 2-way.

    You can breakup "the pyramid" of the larger splitter, but should match all the legs equally between splitters and coax loss/lengths.

    What you don't want to do is to feed a four way off another 4-way, because the last splitter output would equal a 16-way splitter and the coax length would need to be 50-100' total.
     
  7. veryoldschool

    veryoldschool Lifetime Achiever Staff Member Super Moderator DBSTalk Club

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    [​IMG]
     
  8. David MacLeod

    David MacLeod New Member

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    this was helpful to me the other day figuring out optimal "load" and balancing, thank you.
     
  9. PeteB

    PeteB Cool Member

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    Falcon,...
    This has been helpful to me, as well, but I have one question:

    If you have two DVR's in the same cabinet and a 1x2 splitter, all else being equal, is it better to put the splitter right at the SWM, or with the DVR's?

    Stated differently;), split upstream or downstream?
     
  10. veryoldschool

    veryoldschool Lifetime Achiever Staff Member Super Moderator DBSTalk Club

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    It doesn't matter since the loss is a sum.
    coax -> splitter = splitter -> coax.
     
  11. PeteB

    PeteB Cool Member

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    Falcon,...
    That was my guess; thanks!
     
  12. hdtvfan0001

    hdtvfan0001 Well-Known Member

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    I just like all the pretty pictures VOS. :D

    [Still say this should be a sticky :D]
     
  13. veryoldschool

    veryoldschool Lifetime Achiever Staff Member Super Moderator DBSTalk Club

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    what do you think it is?
     
  14. hdtvfan0001

    hdtvfan0001 Well-Known Member

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    :lol::lol::lol:
    Meant to say "shoulda been" not "should be"... ;)

    Plus..you got one more post out of it... :D
     
  15. David MacLeod

    David MacLeod New Member

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    I think a lot (where to split) may also be personal preference. I tend to split close to IRDs to avoid long jumpers and if there is issue can fix (if needed) with short jumper.
     
  16. veryoldschool

    veryoldschool Lifetime Achiever Staff Member Super Moderator DBSTalk Club

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    I mount them where I use the least coax [being a cheap SOB]. :lol:
     
  17. David MacLeod

    David MacLeod New Member

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    :lol: me too, mines due to laziness though :)
     
  18. PeteB

    PeteB Cool Member

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    Falcon,...
    Well, I'll already have two home runs to behind said cabinet, which is why I said "all else equal", but I think I might split there so that I can use the other run for OTA if I end up needing it.

    You can use an AM21 (or whatever the latest is now) with an HR24, right?

    I'll be sure to keep the jumpers a little slacky so that my boxes aren't like shackled together... :)
     
  19. veryoldschool

    veryoldschool Lifetime Achiever Staff Member Super Moderator DBSTalk Club

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    yes, but this is a bit off topic
     
  20. liquidctv

    liquidctv Legend

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    >What you don't want to do is to feed a four way off another 4-way, because the last splitter output would equal a 16-way splitter

    Yep. 4x4 has never worked for me, despite many people yelling in my face that it should, and they have more experience than I do.
     

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