If you have ever needed to wire up more than a couple CATV jacks, you probably encountered the same problems I did while trying to distubute CATV to the 16+ jacks in my house (nooooo, I don’t have 16 TV’s in the house). My distributed setup includes Comcast Digital Cable, with my security cameras modulated on channel 78 and the Antenna 1 (The Greek Channel via Dish Networks) on channel 76 — more on the channel modulation a bit later. The OTA HDTV feed runs from a WineGuard SquareShooter SS-2000 mounted on the roof to the Windows Media Center PC in the equipment room. I can access any content from the MCE via an XBOX, 360 (HD), or Media extender. However, I wanted the ability to connect standard CATV ready displays and displays with CableCards in any room, so I needed to come up with a simple solution.
Here are a few tips I learned:
– You do not need to get 2ghz splitters or amps — Digital Cable only needs 1ghz Bi-Directional spec splitters/amps.
– The best distribution amp I found is ChannelVisions CVT-38BID, I have tried everything from the cheap $10 ones to the more expensive ones like this one… no comparision… get this one!
– Throughly read and study the “Compensating for Video Loss” page on Structured Wiring How To. This site has everything you need to know about distributing cable TV and all the losses involved with splitters.
I ended up buying two 1×8 Leviton 2ghz splitters, again, you don’t need the 2ghz, but it’s not that much more cost for future needs. The 8-way splitter outputs are connected to the remote room jacks. The splitters are feed via a 2-way 2ghz splitter that comes from the 2-way 1ghz splitter/combiner. This combines the signal from the modulator (Greek TV on channel 76) and the filtered CATV signal from the ChannelVision Bi-Directional Amp. The 4-way 2ghz splitter is where the CATV input from the dmarc comes in. I take a 7db loss at that point, and a 5db loss from the main dmarc (point the CATV enters the home) due to a 100′ RG-6 run. So let’s say the db from the street to the dmarc is 25db, by the time I get it into my equipment room, I have 25db – 5db – 7db = 13db ( read the Compensating for Video Loss for more info on this). The 13db is still a good signal and I can use the extra two unamplified ports for testing or for future cable modem needs (currently run DSL 6mb). One of the ports of the 4-way goes to a Digital Cable box, which I could connect directly to the 8-way, but chose not to. The other cable from the 4-way splitter goes to the ChannelVision CVT-38BID for amplification to the two 8-way splitters.
Once everything is connected, and the amp powered up, I just needed to plug a TV on the furthest jack in the house, then check to see if the signal is too weak or too strong. Too weak usually causes noise, too strong you will see waves or a haringbone pattern. Adjustment is easy, just turn a dial until the picture is clear. The main reason why I really like the ChannelVision CVT-38BID is because it has a test input and output which attenuate the signal by -20db. This is a good feature because you can attenuate the input by 20db and amplify the output, or vice-versa. The amp also has a tilt-compensator if you get any signal problems on the higher end of the spectrum — I didn’t need to use that adjustment. Also, if a few of the jacks are a bit to strong you can attenuate them with CATV attenuators. They are available in different values to suit your needs.
In conclusion, setting up a distributed CATV system can be frustrating and a bit complicated, but once you get a basic understanding of how to set one up, everything turns out as good as the final picture.
If there are any CATV installers out there, I’d love to hear if what I did is kosher.