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"backfeed" question

Discussion in 'ViP612/622/722/722K DVR Support Forum' started by aaronbud, Sep 24, 2013.

  1. aaronbud

    aaronbud Legend

    219
    1
    Nov 3, 2006
    My 722k died and I have a new one on the way. My current set up includes the OTA modulator connected via a triplexer. I installed a Toshiba 29" hdtv on my back patio this summer that I have been feeding from the 722k's tv2 output with an RCA analog wireless transmitter/receiver. It's ok, but fuzzy at times. Since I'll have to re-install the new 722k when it arrives, I thought I'd try to somehow get a wired connection to my patio tv. Running a second cable directly to the 722k is not really an option. I'd like to be able to run a cable around the house to where the dish wiring/switch is and get signal from the 722k that I could control with remote #2. I've read on the forum about "back feeding", but I am confused as to whether it's possible with my current set up or not. Any insight on this would be truly appreciated.

    Thank you.
     
  2. scooper

    scooper Hall Of Fame

    6,237
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    Apr 22, 2002
    Youngsville NC
    In your case, since you're using the the triplexer for the OTA feed - you need to run another cable from the TV2 coax to wherever you want it. You can do that to multiple destinations with appropriate use of splitters and amplifiers. Be aware - the output from that coax output is NTSC (equivelent to 480i digital) , but it does have stereo audio output.

    What I'm really saying is that you can't do backfeeding of TV2 AND your OTA feed from your antenna on the same cable.
     
  3. aaronbud

    aaronbud Legend

    219
    1
    Nov 3, 2006
    Thank you for your reply. If I lose the ota, it will work? How do I wire it up?

    Sent from my SCH-I535 using DBSTalk mobile app
     
  4. RBA

    RBA Active Member

    928
    44
    Apr 14, 2013
    TEXAS
    Just as scooper said run a new cable from the back of the receiver TV2 to the patio where your TV is. If you want to provide a floor plan of your house maybe someone will tell you exactly how to run the cable.
     
  5. gov

    gov Legend

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    Jan 11, 2013
    I've had this work:


    UHF OTA <---------------
    [UHF/VHF splitter combiner]----------------------------[diplexer]-------cable to DISH receiver, modulator, TV
    VHF Modulator ---------> to DISH dish<-------











    TV OTA jack <----------------------------
    [UHF/VHF splitter combiner]------------
    channel 3/4 modulator------------------>
    ^^^ {RCA Cables} [diplexer]------------------------ {the above cable}
    DISH Receiver <---------------------------------------------------------------------------





    If there are VHF Hi band locals, they make VHF Lo and Hi band seperators, if you want to go to that degree, LOL. Lotta jumper wires to do this, and I suggest for those who haven't done this before, to just wire the DISH receiver first, and get it working. Then add the diplexers, and verify that DISH is still working, and then insert UHF/VHF seperators in the lines and make sure DISH receiver still works, then connect OTA and make sure that works, then add the modulator.

    If you make an error, you'll know right away, and can fix it. All the diplexers and seperators have different functions on their outputs and inputs and they all have to be connected correctly. Also, the large number of jumper wires all need to be carefully made, no wire whiskers or short center conductors allowed.

    Easy to have this set up turn into a cluster of wire, neatness counts.
     
  6. gov

    gov Legend

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    Jan 11, 2013
    Just remembered DISH DVRs have 2 input lines, use the DISH supplied triplexer instead of the lower diplexer I noted above.
     
  7. scooper

    scooper Hall Of Fame

    6,237
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    Apr 22, 2002
    Youngsville NC
    no need to use VHF - the Dish TV2 modulators are UHF
     
  8. gov

    gov Legend

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    Jan 11, 2013
    Ahhh,


    but the OP wants OTAs at the receiver and to backfeed a modulator upstream too, and only has one wire.


    It's possible to backfeed UHF upstream too, but since I can't be there to supervise, went with a VHF-lo modulator, and still think this is a pretty difficult circuit to get together right for a padawan learner.

    Putting a VHF-hi OTA at the TV is possible too, but it takes even more jumpers and 2 more (weird) splitters and a 2.4 GHz splitter.

    :coffee
     
  9. gov

    gov Legend

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    Jan 11, 2013
    I assume they still make these. I have quite a pile of them and haven't ordered any new ones for years.

    [​IMG]
     
  10. aaronbud

    aaronbud Legend

    219
    1
    Nov 3, 2006
    Thanks for the info, guys. running a cable to the patio would be best, but the only real possible way is to run under the brand new carpet through the wall to the patio. This side of the house has vaulted ceilings, so thats the only option. I'm considering just running a cable to the switch around the eaves of the house, and then just pull the 612 from the bedroom to watch dish on the patio.........I probably just wait until the wireless unit I have craps out.
     
  11. harsh

    harsh Beware the Attack Basset

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    Jun 14, 2003
    Salem, OR
    What are the chances of going under the house?
     
  12. harsh

    harsh Beware the Attack Basset

    21,192
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    Jun 14, 2003
    Salem, OR
    Methinks you've had too much coffee. VHF-hi goes up to 216MHz, not into the gigahertz range as you seem to be suggesting.

    The VHF High-Low Separator/Joiner (HLSJ) that you pictured isn't an option (as scooper pointed out) unless you use an outboard modulator.

    If the TS can't go under-house, it would seem that a wireless solution remains the best.
     
  13. gov

    gov Legend

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    Jan 11, 2013
    The VHF hi needs to be split off, and then combined with the (as I mentioned) existing UHF OTA. The combining is accomplished with the high frequency (they work better) splitter I mentioned above.

    I purposely did not make a diagram for that as it is even more complex than the (now I too late realize) poorly understood circuit that did not include a digital VHF-hi channel.

    :coffee
     
  14. harsh

    harsh Beware the Attack Basset

    21,192
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    Jun 14, 2003
    Salem, OR
    As a conventional splitter/combiner is typically rated up to 950MHz, it will more than adequately cover any and all VHF (and UHF for that matter) frequencies (54MHz to 806MHz). High frequency splitters offer no benefit over conventional splitters in this application.
     
  15. gov

    gov Legend

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    In actuality, there is less loss with the 2.4 GHz variety. For such a mass (mess, LOL) of various splitters and jumpers, as the application is demanding, we need to be cognizant of insertion loss, and of all the jumpers and connectors.

    I've noted with the hi frequency splitters, far less of the signal applied to one of the two "inputs" appears on the other "input", and more on the common output. We want to conserve OTA signal in the deep rural area I live in, and I've learned this and a few other techniques out here.

    (Just saw an in attic antenna install that was performing very poorly for the home owner (that's why he called) and he had the antenna situated so it was aimed thru a valley in the roof. In this area, it is very common for roof valleys to be lined with sheet metal under the shingles, and when I moved the antenna several feet off to the side, the signal was then able to get to the antenna. Everything we know is the result of somebody having a problem, it seems, LOL)
     
  16. harsh

    harsh Beware the Attack Basset

    21,192
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    Jun 14, 2003
    Salem, OR
    In actuality, this is NOT true.

    Using the popular Holland branded splitters as an example, the wideband splitters have quite a bit more loss in the VHF-hi band:

    2-way standard 3.6dB
    2-way wideband 4.3dB
    4-way standard 7.2dB
    4-way wideband 7.8dB

    The products from PerfectVision have specs that reflect a similar relationship.

    If you're not using cable TV (where the wideband performance may be of interest), the old school 950MHz splitters offer less loss.
     

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