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Longest Cable run?

Discussion in 'DIRECTV Installation/MDU Discussion' started by iotp, Oct 15, 2010.

  1. Oct 15, 2010 #1 of 139
    iotp

    iotp AllStar

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    Question surrounding the coax length maximum length. From the DirecTV dish to the receiver, whats the longest cable run you can have? Are there some sort of repeaters? Signal amplifiers?
     
  2. Oct 15, 2010 #2 of 139
    matt

    matt New Member

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    It can be several hundred feet, but with some conditions.

    What are you wanting to do and that will help us advise you better.
     
  3. Oct 15, 2010 #3 of 139
    BattleZone

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    The devil is in the details (and the price).
     
  4. Oct 15, 2010 #4 of 139
    carl6

    carl6 Moderator DBSTalk Club

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    Some approximates:

    RG6 coax with solid copper center conductor: Recommended not to go over about 125 feet. May work reliably up to approximately 200 feet.

    RG11 coax: Probably run 200 to 300 feet.

    If you need to go longer than that, as matt1124 said tell us what you want to do and specific advice can be given.
     
  5. Oct 15, 2010 #5 of 139
    veryoldschool

    veryoldschool Lifetime Achiever DBSTalk Club

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    "Generic" 100' RG6 solid copper core:
    RF loss @ 2150 MHz ≈ 10 dB
    DC voltage drop, with 500 milliamp load ≈ 0.5 Volts
     
  6. Oct 15, 2010 #6 of 139
    BattleZone

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    [​IMG]

    My most recent commercial install was 2 D12s in an office building. 18" dish on the roof (essentially the 21st floor), with one receiver on the 17th floor (approx 275' from the dish) and one on the 9th floor (approx 400' from the dish). Copper-clad-steel RG6. Works fine.

    BUT, add a non-powered switch to the mix, and the 9th floor will probably die.

    Doing commercial work, you learn that the sat companies build a BIG margin in their specs.
     
  7. Oct 15, 2010 #7 of 139
    veryoldschool

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    Hope it doesn't rain there :lol:
     
  8. Oct 15, 2010 #8 of 139
    Renard

    Renard Godfather

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    I have 225-250 feet of SOLID RG6 copper cables (one for each tuner) from the dish to my HR20-700 and I don't experience any problems even when it's raining here in Seattle.

    I strongly recommand SOLID copper over clad steel (of course more expensive).
    The problem is not signal strength, but power the LNBs for each sat (13-18V, 22KHZ) when you run long cable.

    Hope it helps
     
  9. Oct 15, 2010 #9 of 139
    BattleZone

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    Downtown Oakland. If they have 10 minutes a year of rain fade, I'll be very surprised.

    Signals are strong at the receiver. It's the voltage that becomes a problem much earlier than signal loss.

    Though I did an experiment with a SWM16 the other day. 150' to the first 2-way splitter, and then cascaded 2-way splits every 50'. 5 splits still worked, but signals on the 5th receiver were low (70s). The 6th split resulted in zero signal. Obviously, YMMV.
     
  10. Oct 16, 2010 #10 of 139
    iotp

    iotp AllStar

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    I work in an airport, we recently pulled some conduit. I was thinking of using this to get to the area.

    The run is well over 600 feet. Problem is dealing with the airport authority. We are in the basement of a major metropolitan airport and getting a dish and signal to the area we are has been a 5 year ordeal.

    Ugh, back to the drawing board.
     
  11. Oct 16, 2010 #11 of 139
    veryoldschool

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    You may need to look at using RG11 and even then adding an amp or two along the way.
     
  12. Oct 16, 2010 #12 of 139
    matt

    matt New Member

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  13. Oct 16, 2010 #13 of 139
    byrd

    byrd Legend

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    In post #19 of this thread, BattleZone refers to a 600 foot run that was completed using RG11 and a legacy dish. That might give you some additional info. Edit - Looks like matt1124 just beat me to the punch.

    On a related note, does anyone know what affect the non-75ohm coax would have on the transmission of sat signals? I was just wondering, for extremely long runs, if low loss coax like LMR-400, 600, or 900 could be used. The center conductors have a considerably heavier gauge than RG11, but it's 50ohm cable. We typically use this for 2.4GHz radio communications.

    I have have a couple lengths of unlabeled coax in my system that I strongly suspect are RG8 (installed by a D* tech 8 years ago and never replaced - it's buried and I don't want to dig it up). After just checking out this chart I see that RG8 is 50ohm cable and it seems to work fine for my setup. It's only a 50ft run though.
     
  14. Oct 16, 2010 #14 of 139
    veryoldschool

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    Since it's the wrong impedance the forward path losses will be greater and the reflected signals too, so instead of a "win - win", you'll have a "lose - lose" condition.
     
  15. Oct 16, 2010 #15 of 139
    AntAltMike

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    I once serviced a stacked (2,025MHz) DirecTV system that was engineered by Sonora design where the signal went 660 feet through RG-11 before being amplified. At that point, it went into a 36 dB gain amplifier and was split into two branchlines, one of which went 330 feet before being amplified again, this time 30dB.

    Is this system going to be supporting a lot of tuners? If so, then there will have to be four coaxes pulled, with loss calculations made at 2,150 MHz, and the control voltages will have to be maintained to assure proper polarity selection, whereas if you are supporting just 8 or 16 tuners, you will need only one or two strands of coax with losses calculated at about 1,800 MHz, and you can "goose" the DC you are injecting into the line to assure that its strength is adequate at the LNB. I once put a generic, 20 volt power supply in a DISHPro system just to make sure the voltage was robust enough at the 400' distant LNB.

    Often times, it is impractical to amplify a long coax at a midpoint, and so, if your calculated signal strength level at the amplification point really needs to be in the mid, minus-60 dBmV neighborhood or higher, and even then, you are lacking much of a cushion for rain fade.

    IF you have someone in house who can do even primitive circuit design, it wouldn't be that hard to inject AC voltage into the coax, like the cable company does, break it out at the DISH end of the coax, and convert it to DC there to support a power locker and booster amplifiers.

    One problem with pre-boosting SWM signals at the dish end of the coax is that available, two-way SWM amplifiers do not have the power handling capability of one way amplifiers.
     
  16. Nov 20, 2010 #16 of 139
    InsiderOK

    InsiderOK New Member

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    Hey guys... I am needing some help with this exact issue. My parents living in Atlanta have FINALLY (I have been working on them for two years...ever since I got Direct) decided to switch from Charter to Direct. They had an installer out this morning and he told them the cable run was too far. They are having three receivers installed, one HDDVR, one HD, and one SD, and the two HD receivers will have Whole Home installed. They have to put the dish at the front of the yard because of trees, resulting in a cable run of about 150-160 feet to the first receiver (or about 5 feet less if counting to just inside the craw space). I am hoping that this installer was just being overly cautious (or lazy) and they can still have Direct installed if they just ask for another installer. What do you guys think?
     
  17. Nov 20, 2010 #17 of 139
    P Smith

    P Smith Mr. FixAnything

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    Carl6 did answer you already - read his post above (#4).
     
  18. Nov 20, 2010 #18 of 139
    InsiderOK

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    I did see that, but my main question was if they need to ask for another installer or if no installer will do it since it is over 125 feet (the rec. distance for RG6)...
     
  19. Nov 21, 2010 #19 of 139
    joe diamond

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    That could be a magic number without reference to engineering. If you consider that 125 x 4 =500 and that is the number of feet in a box of dual cable what they are telling you is they will not invest more that one box of cable per installation. Know that the slimline Ka/Ku requires that four lines be buried...not kicked into the sod....and that is a lot of shovel time. As mentioned above there are ways to do long runs. Think $$$$$$$$!

    Joe
     
  20. Nov 21, 2010 #20 of 139
    BattleZone

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    No installer is going to do that job as a "standard installation", meaning, for the meager pay they get from DirecTV. As Joe points out, cable costs alone would eat up nearly the entire pay for the job, and that's not including any of the other cabling needs, or any labor.

    If you want the install done, either hire a private contractor to handle the cables from the dish to the house, or do the work yourself. Dig a trench, and run 2" conduit with sweeps on each end, from the house to the dish. Take measures to keep dirt out of the conduit. Then, you can put a plastic bag on the end of a pull twine and suck it through the conduit with a shop-vac. Cut your 4 cables the length of the run +40', so that you'll have 20' on each end to work with. Tape the first foot or so of the cables to the pull twine and pull your 4 lines through the conduit.

    IMPORTANT: you need to have someone feeding the cable into the conduit, and the person pulling should just keep pressure on the line, so that the cable moves as the FEED person feeds. If you try to just pull the line through, bad things can happen.
     

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