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four receivers on directv ??

Discussion in 'Archived Threads 2001-2004' started by David Wilbanks, Aug 19, 2001.

  1. David Wilbanks

    David Wilbanks Auditioning

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    What's the best and cheapest way to run 4 receivers on directv? What will be needed? What kind of switches? Does a powered switch mean that the signal is amplifieed at the switch? Thanks for any help you can give me........
     
  2. James Reyes

    James Reyes Stunt Coordinator

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    If you are looking only at one sat (101) you simply need a standard DBS four-way multiswitch. A powered switch does not mean it amplifies. The switch needs power to actually do its thing, i.e. switch. The receiver sends back at the most 18 volts which isnt' sufficient to power the switch. You will also need a dual LNB on your dish.
     
  3. James Reyes

    James Reyes Stunt Coordinator

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    Hmm... do you use both receivers simultaneously? See basically the deal is polarity. In order to maximize bandwith, satellite frequencies are polarized, i.e. adjacent frequencies travel in the air differently to avoid interference. Some channels fly through the air clockwise, or what is called righ-hand circular polarity (RHCP) and some travel counterclockwise, left-hand circular polarity (LHCP). Without going into too much detail, odd transponders are RHCP and even transponders are LHCP. On C-band a transponder is a channel, on compressed DBS, multiple channels reside on one transponer. The LNB cannot pick up both polarities at the same time, it must switch to one or the other. If you have two receivers, each must have it's own LNB so it can have both polarities available to it at any time. A dual LNB is literally two LNB's in one enclosure sharing the same feed horn. So, one output can be on LHCP and the other on RHCP or any combination of the two. Each output of the LNBF are total independent of each other.
    The polarity switching process is executed by voltage fluctuations from the receiver. When the receiver needs a channel that is on an odd transponer (RHCP) it sends 13v back to the LNB and when it needs a channel on an even transponder (LHCP), it sends 18v. Now, let's say, as an example, that Nickelodeon in on an odd transponder (RHCP) and HBO is on an even transponer(LHCP). In your set-up both receivers are hooked up w/ a splitter to a single LNB. Receiver 1 is tuned to Nickelodeon and then someone goes to the other room and turns on the receiver and puts it on HBO. Receiver 1 was sending 13v and now receiver 2 is sending 18v. When the voltage meets at the splitter, the 18v will win out and the LNB will switch to LHCP and guess what happens to Nickelodeon? Signal out. Now this set-up will work if you only use one receiver at a time or if both receivers are tuned to the same polarity.
    Now the way a multi-switch works, like the 4-way, is the switch is hooked to a dual LNB on one end and up to four receivers on the other end. The switch will send out a constant 13v on one side and a constant 18v on the other, resulting in both polarities being sent to the switch at all times. It then is able to distribute either polarity to each receiver based on the voltage it gets from the receiver.
    Hope that made sense [​IMG].
     
  4. Michael Jsmith

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    What a great explanation! I, too, have two receivers running from just a splitter. Now I finally understand why sometimes they both work (get different channels at the same time) and why other times one or the other can't find a signal. Guess I'll go ahead and hook up another line from the 4-way multiswitch my dish has built-in. Should have done it that way the first time-- Proof again that it rarely pays to do things the lazy way! Thanks for the great post.
     

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