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Old 21-Jan-2010, 6:29 PM   #2
mtownsend
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Join Date: Dec 2009
Posts: 632
Hello and welcome!

Quote:
Originally Posted by FolFool View Post
I'm in an 8-year old home with a wiring distribution system that goes into a CM splitter/combiner in a box in a closet.
Does this splitter have any amplification? When a signal feed is split, less power will go down each branch of the split. It sounds like this is a 4-way or 8-way splitter.



Quote:
I noticed there's what looks to me to be a spare CAT 5 cable run in the attic, so I'm hoping if I install an antenna there and hook it up to the cabling I can just change the input in the combiner and, voila, Comcast out, OTA in.
Are you suggesting to connect the antenna to the CAT 5 cable? Just so you know, this will not work very well. The impedance mismatch between the different systems will cause lots of signal loss. You need to keep the OTA signal in its native 75 ohm coax, preferably RG6.



Quote:
We will eventually have 3 HD TVs connected, but there are at least 2x that many coax connector jacks (?) throughout the house.
That is fine as long as you terminate the unused ports (inexpensive F-type terminators are available for this). This will prevent any open-ended ports from "reflecting" the signal back into the coax and potentially causing self-interference problems.



Quote:
So if I can really use a set-top antenna to get those stations (including 2 in the Hi-VHF area), is it unreasonable to hope that an attic antenna would also work?
I think an attic installation would work best. If you use an antenna like the Antennacraft HBU-22, it will adequately handle channels 7-69. Since it is significantly better than your average set-top antenna (but probably still in the same price range), it should be able to provide enough extra signal to overcome the loss of your long coax run. The added directionality of the HBU-22 over a set-top antenna can also reduce the impact of multipath (signal reflections from the environment that can make channel decoding more difficult). This will improve your chances of getting a clean signal to your TV that is easy to lock on to.

I would avoid using any pre-amp for now. Your signals are strong, so a pre-amp would be at risk of being overloaded if installed right after the antenna.

If your distribution splitter has a built-in amp, I would leave that in for now. The line loss between the antenna and the distribution splitter might be enough to bring the power down to a level that can be handled by the amp without overload. If we discover signs of amp overload, we can discuss ways to disable or bypass the amp later.

If the distribution splitter does not have an amp, then we'll just leave it that way. Your OTA signals are probably strong enough to drive a clean signal to each TV despite the multiple splits. Again, I'd try the most straightforward thing first, and if adjustments are needed, we can deal with those later.
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