Tricky Dish Network signal splitting

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Old 02-14-11, 09:12 AM
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Tricky Dish Network signal splitting

I have dish network which is wired in the following way:
Signal from dish antennas goes into a junction box (outside the house) then to the receiver (Dish 722) downstairs (There is a splitter right before the receiver to feed into both tuners, I believe). The receiver gives me two independent TV signals, one goes straight to the TV there, the other one goes back out the same cable to the junction box. (At this point I believe it is a standard analog (cable?) TV signal, since the TV receives it that way.)

From the junction box there are feeds for several upstairs rooms. The second TV signal currently goes to one room. I can split it off here to go to a second room, which is what I am trying to do, but if I do, the loss of power causes the picture to become grainy. I tried installing a signal booster on the line coming from the wall to the receiver downstairs (to boost the signal going back outside) but when I do, I lose the incoming signal. This is a powered Motorola signal booster that is supposed to boost the signal in one direction while allowing the return signal to also pass, if I understand it right. I believe the signals from the satellite dish are outside the frequency range that the booster can handle so it is not passing the signal from the antenna to the receiver.

Can anybody see how I can amplify the outgoing signal (receiver output) while still allowing the incoming signal (antenna to receiver) to pass through? I can't put the booster outside (where I wouldn't have to worry about the incoming signal) because I don't have a power source out there (it uses 12V DC).

Is there a way to do this?
Thanks,
Clay
 
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Old 02-14-11, 04:13 PM
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Hi Clay,
Welcome to the forums.

Satellite signals are not only higher than the frequencies that a typical booster can handle, the dish is also powered by that cable. Most boosters won't pass that power. Worse, the return paths of the boosters are usually limited to frequencies under 50MHz.

See if I'm understanding correctly:

The cable from the dish to the receiver shouldn't pass through a splitter in the j-box. It should go directly to a splitter at the rear of the receiver. The splitter feeds both inputs of the dual receiver. The frequency passband of that splitter is typically 1GHz to 2.1GHz -- well above the bandwidth of the TV channels and booster, which are typically 5MHz to 900MHz.

The TV closest to the receiver is connected to TV1 which utilizes the IR (line-of-sight) TV1 remote. It is connected to the TV with A/V or HDMI cables.

The output of the second receiver is a menu-selectable standard-def channel that uses the TV2 remote. This remote is not line-of-sight, and it can be used anywhere in the house. The output of the TV2 receiver should connect with a dedicated cable to the splitter in the j-box to feed the rest of the TVs. You can insert your booster between the output of the receiver and the cable that feeds the j-box. If you don't have a second cable from the receiver to the j-box you need to run one.
 
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Old 02-14-11, 07:50 PM
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For starters - go into the 722 menu under modulation and change it to a lower ch , such as 22. It's probably at the default of 60. this alone may help some graininess on tv2 pics. Change/get a quality splitter for the junction box, see if this helps.

fred
 
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Old 02-14-11, 09:42 PM
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More info

Rick,
You have it pretty much right.

The first thing the signal from the antenna does is go through a diplexer (backwards, that is into one of the "outputs") at the junction box and then into the receiver (splitting into two TV1 and TV2 at this point). The output from TV2 goes back out to the junction box and through the previously mentioned diplexer. The CATV signal goes from here to TV2, which is upstairs. This is where I can split the output and go to TV3, which is just a clone of TV2.

I called the local Dish installer company and the guy told me it should be able to feed 3 or 4 TVs on that output (TV2) without boosting it. He told me to check the connections and try changing the channel from 21 (over-the-air frequency) to 73 (cable). I did and I seem to be getting a cleaner signal now. It's not perfect, obviously, because its an SD signal, but I think it is fixed. I still want to check when I have a chance if it is as good as the unsplit signal, so if anyone knows a way to get the booster to work I'd be glad to hear it.

Thanks for the quick replies!
 
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Old 02-15-11, 05:40 AM
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Some boosters are designed to be powered through the cable, which allows them to be placed anywhere you need it. Power is injected where it's convenient to plug it in to AC power. As long as you're not using the same cable as the sat dish you might try it. This would connect between the diplexer and TV2. Here's a sample.

The tech is correct, though. My sat dish CATV output is up around +15dB, which is plenty to feed several TVs. I don't know what kind of insertion loss the diplexer is subtracting (-3.5dB?), but each 2-way split loses -3.5dB. Each 100 feet of RG6 cable loses another -3dB at TV freqs and -10dB at sat freqs. Add it all up and you should still have a decent signal at TV3.

+15dB at the output of receiver TV2
+12dB at the far end assuming 100 feet of cable
+8.5 after the diplexer
+5 to TV2 and TV3 after the splitter, which is plenty of signal.

Also keep in mind that too much signal can damage the tuners in the TVs. You really don't want to hit them with more than about +15dB.
 
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Old 02-15-11, 06:01 AM
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You may have been receiving some local interference on air 21. Cable 73 frequency is still very close to air 21. air 22 and cable 73 are almost identical frequencies.

try some other modulated channels.
you should not need the amp at all!!
fred
 
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Old 02-15-11, 07:42 AM
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OK, thanks. Will try some other channels.
 
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Old 02-15-11, 09:29 PM
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Also, if you use an output of a splitter to inject the signal, the other feed should be in the other output. I ran into this when I connected my OTA antenna. The receiver's signal was fine for a day or two, but eventually failed until I swapped the OTA from the input to the output and used the input to feed the TVs.

Splitters can work as combiners provided there is no other channel on the system. You don't say what city you're in, snoweel, but if you're in a large market you may have to change the TV2 channel several times before you get a clean picture.
 
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