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Signal Problem, Downgraded LNB

Discussion in 'DIRECTV HD DVR/Receiver Discussion' started by SEAKevin, Jul 30, 2012.

  1. SEAKevin

    SEAKevin AllStar

    51
    0
    Jul 8, 2006
    I've got my dish mounted on a wooden fence and I've noticed that every 2-3 years I need an alignment. Also, my neighbor has a maple tree that is growing steadily and I think it's interfering a bit.

    A few months ago I noticed signal degradation especially in the 110 and 119 satellites (119 was down to around 70% and 110 was at zero), but also a couple of my 99 transponders were at 77%..when performing a system check I would get an error message saying there was a dish alignment problem. But none of this was causing me any issues until the last couple weeks.

    I had 2 HR21's..and one of them was having real problems with picture quality and it would get very temperamental when watching recorded shows to the point it was becoming unusable. But the other HR21 was working fine. So I called and they sent out a tech yesterday.

    But before he tried realigning my dish he swapped out my Slimline 5-LNB with a 3-LNB (still the same dish..just new LNB). He told me that I would no longer see satellites 110 and 119..but 119 is Spanish programming and 110 is not in use so it's no loss for me... I was a little surprised he did this even before trying an alignment first... but in thinking about it I guess it's better in my situation (with my wood fence/tree issue) to have the receivers looking at fewer satellites to avoid slow processing times when signal problems arise with 110/119 if I don't even need them.

    He ended up replacing one of my HR21's with an HR24...I am very happy about that..the HR24 is so nice and fast. After the alignment all of my signals are back in the high 80's-mid 90's where they should be... minus 110 and 119. Actually eliminating these 2 satellites has made my remaining HR21 perform a little faster (at least it seems like it).
     
  2. Shades228

    Shades228 DaBears

    6,081
    46
    Mar 18, 2008
    Wooden fence posts will move, expand, contract, and can swap with age. If your locals don't come from the 119 and you do not subscribe to spanish, jadeworld, or care about a specific couple of channels then you don't need the 110/119. Changing the LNB would not increase your signal strength alone tweaks had to be made and he probably did it while he was swapping the LNB.
     
  3. TomCat

    TomCat Broadcast Engineer

    4,153
    101
    Aug 31, 2002
    I don't think you would get slower processing times. The only processing is in your DVR, and it is only concerned with signals that you are actually tuned to, and signals being read from the HDD. Anything else, including signals you are not tuned to, is just as non-relevant to you and your system as whatever signals my system is tuned to.

    Sats not in use are not being looked at, other than by the LNBF on the antenna, and that is just a dumb analog reamplifier/heterodyne converter; if a signal comes in to its focal point that is on the right frequency, it amplifies and block converts it to L-band and sends it to its output, and if nothing comes in, nothing goes out. That's the limit of what processing it is capable of and none of that invokes digital delay or latency, because it is analog.

    If there is a signal, that is made available to the multiswitch in the LNBF array, another dumb analog device. But since you receive no signals on your STB from those sats, the switch is never instructed to switch the matrix to that port anyway, so whether there is a signal there or not is really a moot point, just like if you never turn your FM radio to Hot93, you will never know when they go off the air. And none of any of that invokes "processing", other than instantaneous analog processing.

    But one common failure of the LNBF is to lose the ability to amplify, which is often a gradual decrease in output gain over time. Any time current flows, heat is created, and that eventually can cause board-level components to change value. It is not unlike what happens to a projection TV lamp (although not as dramatic or predictable); it gets old and starts to wear out and just can't do the same job it could do back in the day (I can relate). An LNBF that is 7 years old, for instance, will likely not perform as well (will not amplify the incoming signals as much or as consistently flat over the operating band) as one fresh out of the box. The incoming sat signal usually stays relatively the same (assuming proper alignment), but the LNBF's output levels that feed your DVR tuners' front end will start to gradually go lower, which will lower the rain fade margin and eventually cause pixelation issues, mimicking poor alignment or obstruction.

    If you align your antenna and it still does not seem to have the gain it should have, a new LNBF array is probably the smartest first step (the reflector is still as good as it was on day one).

    Why did he change it out before attempting an alignment? Since the cost of that does not come out of his pocket and since he may get a spliff just for "having" to replace it, both he and you are probably both better off doing that first, and if he knows how old your original LNBF array is going in, that might actually be the smartest first step.
     

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