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#179715 07/28/08 06:24 PM
Joined: Mar 2002
Posts: 179
derater Offline OP
I'm a resi guy and do the tv cable for new builds, but never cared what the dish guys were doing 'cos they also did final termination. I'm building an addition on my own home now, and have NO idea what to run for future dish tv. Shame. Can someone fill me in ? Thanks.

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Joined: Jan 2005
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Cat Servant
I suggest you drop by the chat room in a bit .... there's usually a "dish guy" or two there.

Joined: Apr 2002
Posts: 156
Four Rg-6 for a dual LNB with HD.

Joined: Jul 2004
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You need 4 RG6s to each TV?

Greg Fretwell
Joined: May 2003
Posts: 1,158
Depending on the system there is combiners and separators to use on a single line if your going to use dish network equip.
some of the receivers that have the hard drive for recording will either require the latter or 2 lines ran to that room.

any how its best to run 4 lines from the dish to a central location where the home runs from all the rooms would come too also.

What type of system are you installing and how many receivers. Direct TV is another story.

Joined: Nov 2005
Posts: 827
If you are using multiple receivers, a switch will likely be involved. Basically, you need one RG6 cable for each polarization of each bird that you are looking at, between the dish and the switch. You need one RG6 for each tuner in your receiver to the switch. Polarization is controlled by the DC PS/tuning voltage sent to the LNB. CW and CCW from each feed must be provided to the switch so that any tuner can select either with its tuning voltage. A tuner may also send a low frequency AC signal up the coax to the switch to select a different bird. I just have the old parabolic dish with a dual LNB and 2 single tuner receivers. In my case, it's just one RG6 from each receiver to the LNB. The tuner will switch between about 12VDC and about 18VDC to select polarization. Most of today's dishes are hyperbolic paraboloids to handle multiple feeds on the azimith axis. I think there might be a configuration ot there with 3 birds but only 4 cables needed because of some sort of FDM (Frequency Division Multiplexing)

Joined: Oct 2006
Posts: 745
Joe, any chance we might be able to get the English version of that answer? grin grin


"But the guy at Home Depot said it would work."
Joined: Nov 2005
Posts: 827
I guess my answer might only make sense to those who already understand how the system works. I'll have to work on a better one. Azimuth axis wasn't a good term either. The skew angle and the hyperbolic shape are used to focus the feeds over a small portion of a polar arc that covers the 2 or 3 satellites used.

Joined: Mar 2005
Posts: 1,213
LOL, I don't think that was any better!

Translation to english: they stretch the dish a little bit so it can look at multiple satellites without having to move. But you still need 1 RG6 for each of the 4 satellites you're looking at. And you need a switch so that your TV can switch between the 4 lines.

Joe, let me know if I get this right:
1) Find a good spot to put the switch.
2) Run 4x RG-6 from the dish to the switch.
3) Run 1x RG-6 per TV to the switch. Or, 2 if you have a Tivo or another dual-tuner DVR (highly recommended, btw!!), because each tuner needs to be switched independantly.
4) In fact, just run 2x RG-6 to every room in the house, just in case you put a TV there at some point. RG-6 is cheap.

Joined: Nov 2005
Posts: 827
You're close Steve! You still need 2 RG6 cables for each satellite though. If you had one tuner looking for a program on a clockwise polarized transponder, while a different tuner was selecting a program on a counter-clockwise polarized transponder of the same satellite, there would be a conflict.

Now this is what I'm not at all sure of. I'm hearing that some HD programming might be coming off of a third bird without increasing the cables needed to 6. The output of that LNB is above the upper limit of the 950-1450 MHz of the other LNBs so it can be multiplexed on the other cables. An in-line unit at the tuner can let the 950-1450 MHz in and let tuning voltages and switching frequencies out. But it can also, supposedly, accept another unique signal from the tuner. This signal triggers the inline unit to block the original 950-1450, and do another block down conversion on the higher frequency signal.

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