Multiswitch and diplexers

Discussion in 'DirecTV TiVo Powered PVRs & Receivers' started by OaklandRobb, Aug 28, 2007.

  1. OaklandRobb

    OaklandRobb New Member

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    Jul 1, 2001
    Oakland, CA USA

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    This is NOT a question about the 5 LNB dish and diplexers. I know that is not supported. But I have a 3 LNB, with 4 DirecTivos, two of them being HR10-250s. I had them running on a 4 x 8 switch with no problems. Since I only had one HD TV, I took my antenna lead, ran it into a diplexer, ran a short cable from the multiswitch into the diplexer, and then my regular cable to a diplexer at the Tivo end. All worked fine and I got my HD local off the air channels and my satellite channels on that TV with no problems.

    However, because I was buying a second HD TV, I purchased a Perfect Vision 5 x 8 multiswitch from Solid Signal. I installed it and all satellite channels continue to come in fine. However, I was not successful with the antenna. The way I hooked it up was to attach the antenna cable to the Terr connector on the switch. I ran the cable that used to go from diplexer to diplexer directly to the switch. I did not use a diplexer on the switch end. I left the diplexer at the TiVo end unchanged. But with this setup, I did not get a picture on my local stations - 5-1, 7-1, 11-1, etc. I went back to my previous setup with a diplexer at the switch side, with the antenna lead running into the diplexer, and everything was fine again. But that does not give me a way to connect the second TV for off the air locals other than running another line directly. It also means that the 5 x 8 was a waste of money.

    I contacted Solid Signal both by email and phone. The tech support guy on the phone told me that no multiswitch does diplexing and that I needed a diplexer at the switch end. He could not explain the benefit of a 5 x 8 switch over a 4 x 8 switch or how to hook up the diplexer other than how I was already doing it.

    The tech support guy who answered my email said I need to either add a preamp, or change to Channel Master diplexers. Currently, I am using Perfect Vision diplexers, although he does not know that.

    Is what either of them saying true? Do I have a defective multiswitch? Is there a different way to hook this up, that I am not thinking of other than running additional cables from the antenna to each TV?

    I am hesitant to spend more money on this 3 LNB setup, since I know sooner or later I will need to switch to the 5 LNB and give up the diplexing strategy. But I am hoping to put that off for awhile, and the $50 for the Perfect Vision multiswitch seemed a reasonable way to do that.

    Any help you can provide will be much appreciated.

    Thanks in advance.


    Robb
     
  2. JimSpence

    JimSpence Just hangin'

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    Sep 19, 2001
    Binghamton, NY
    With you original setup you had very little signal insertion loss with the diplexer. Now by connecting the antenna to the 5x8 switch you have much more signal loss (essentially an 8 way split). I think some switches can amplify the OTA input to make up for the loss. If you only need the OTA at one receiver, I'd go back to diplexing it on the line to that receiver. Otherwise, an amplifier on the antenna before it's connected to the 5x8 should also work.

    What frequencies are the missing channels using? These may be on one end of the spectrum or have lower power.
     
  3. OaklandRobb

    OaklandRobb New Member

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    Jul 1, 2001
    Oakland, CA USA
    Thanks for the reply, Jim. I happen to have an old Radio Shack 10db amplifier from the days that I had cable. I will give that a try and see the result. It may not be enough, but sounds like a good first step.


    Robb
     
  4. Vin

    Vin New Member

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    Jun 13, 2003
    Clifton, NJ
    I think the amp will solve your problem but if it doesn't I'd try a two way splitter on the antenna line (less signal insertion loss than the 8 way split from the multiswitch) and then use diplexers to send the OTA feed to your 2nd HDTV....I doubt the amp will be necessary with the 2 way split.
     
  5. OaklandRobb

    OaklandRobb New Member

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    Jul 1, 2001
    Oakland, CA USA

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    I tried my experiment with my old Radio Shack 10 db signal amplifier, and now have a bit of a mystery. Likely it is just a mystery to me, and Jim or someone else with more understanding of these things will explain it. Before adding in the amplifier I reconnected the antenna lead to the switch and removed the diplexer. The first day I tried this I just saw that I had no picture on my over-the-air channels and suspected the multiswitch or my hook up. This time I wanted to check the signal strength as recorded on the HD Tivo. Just as Jim predicted, I was getting a signal, but it was quite weak and jumped up and down. With my weakest I was getting a peak of 34, with my strongest, a peak of 50. I then went back to the basement to add in the amplifier. When I checked the signal strength, instead of a little bit better or even much better, it was at 0. No signal at all. I started thinking, bad connecting cable, mixed up in and out, dead amplifier, dead power outlet. But as I was turning away thinking of how to deal with each of those possibilities, I noticed that the peak reading was indicating 95 and 100. I went back down and confirmed the power outlet was good, good connections, and remembered that the last thing I had done was to plug in the amplifier. Was it possible that the amplifier worked better without power? I unplugged it from the power, but left it connected to the switch. When I went back to check on the TV, I had great signal strength and great HD pictures on all over-the-air channels. I am not complaining, but how does the amp work without power?
     
  6. JimSpence

    JimSpence Just hangin'

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    So you are saying that the amp was unpowered but connected to the antenna? Now that is weird! An amp without power should almost block any signal. As a test, use one of your sat lines for the antenna to the receiver.
     
  7. OaklandRobb

    OaklandRobb New Member

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    Jul 1, 2001
    Oakland, CA USA
    Yes, with the Radio Shack 10DB amplifier plugged in to power, the signal meter in the HD Tivo registered zero, zero. With it unplugged from power, but no other change in connections, it registered 95, 100. However, last night, although I didn't check the strength, it had clearly gone down for one my channels (PBS) which usually comes in strong, or did with my old hookup, to the point that it was unwatchable and had no sound. Other over-the-air, were good.

    Sorry Jim, this is all pretty new to me. I am not understanding your last suggestion - "use one of your sat lines for the antenna to the receiver". I need all the details. What should the antenna be plugged into? what should I have at the receiver end. Currently, it is antenna to amp to switch. Switch to room and then diplexer split to sat and antenna connections on the Tivo.


    Robb
     
  8. OaklandRobb

    OaklandRobb New Member

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    Jul 1, 2001
    Oakland, CA USA
    As soon as Solid Signal has more of these in stock I will get a couple.

    Channel Master 4001IFD VHF/UHF Satellite Diplexer/Separator (CM4001IFD)

    At $6 each they are cheap, and I understand there is very little signal loss.
     
  9. JimSpence

    JimSpence Just hangin'

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    Instead of using one of the sat lines from the multiswitch to the receiver, use it as the feed from antenna to the ant input on the receiver. Specifically, use a F/F barrel connector to connect the antenna coax to one of the sat lines going to your receiver. At the receiver us that line and connect it to the ant input on the receiver. This removes all variables from the equation. You have a straight connection from antenna to HR10 to see how it affects your reception.

    As for the amplifier, it's possible that it is overloading the HR10's OTA tuner causing a total loss of reception. You just have to play around with different combinations.
     
  10. OaklandRobb

    OaklandRobb New Member

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    Jul 1, 2001
    Oakland, CA USA
    OK, Jim. Now I understand what you are suggesting, and I will give it a try on Saturday. But since going from the antenna into a diplexer, mixing in the satellite and then into a diplexer at the receiver works quite well, I expect your idea will get me better signal strength, although likely not a better picture. But I don't see how it will solve the mystery of why my signal amplifier works well with no power, and leads to no signal with power. But it is easy enough to do, so why not. I know my best choice is to just use a splitter for the antenna and run another cable to each TV without diplexing. I also know I will have to do that when I break down, get the 5 LNB and the latest non Tivo HD DVR from D*. I am just trying to put off the day.


    Robb
     
  11. JimSpence

    JimSpence Just hangin'

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    As I implied with the amplifier, the signal could be overloading the OTA tuner. It's still possible that a direct connection will also overload the tuner if your locals are close and are high powered. With the amp unpowered, this is the same as putting an attenuator in the line, bringing the signal down so that the tuner can lock on. Your original diplexing setup possibly attenuated the signal too much, thus also causing a lack of lock on. Using a 2 way splitter on the antenna may attenuate the signal just enough to work.

    All this is why I said it is an adventure of trial and error.
     
  12. Carlosrjr

    Carlosrjr New Member

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    May 22, 2003
    Hey Jim, I recently purchased a HR20 to replace my networked DSR7000 that died. I had two DSR7000 and using a multiswitch and diplexer @ the point of entry receiver (garage) and a diplexer prior to connecting the receiver. This allowed me to run two TVs from one receiver.
    The installer said that diplexers would prevent the loband HD signal from functioning. Other than running an separate run from the satellite to my vcr (input from HR20) I am screwed. Luckliy I remembered that I had an AV Sender & receiver and was able to send the signal to the tv upstairs. Not a bad option but wondered if I could actually use diplexers and multiswitch to achieve the same result. thanks
     
  13. JimSpence

    JimSpence Just hangin'

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    Basic info for those that may read this thread. Multiswitches are used to create extra outputs for use by DirecTV receivers. Diplexers are used to combine/separate sat and OTA signals. With the implementation of MPEG4, diplexing on those sat lines now can't be done. This is why the new multiswitches for MPEG4 don't have an OTA input.

    Having said all that, if you have a sat line that isn't used for MPEG4, you could diplex onto it.
     
  14. jimrobinette

    jimrobinette New Member

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    May 21, 2003
    Seattle
    All,

    It IS possible to diplex with MPEG4, you just have to be creative!

    See: http://www.dbstalk.com/showthread.php?t=62299

    Jim

     
  15. JimSpence

    JimSpence Just hangin'

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    Sep 19, 2001
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    True.

    However, it would be less trouble to just run separate cable from OTA to receivers.
     

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