Comcast XFINITY TV → Cable tv and cable modem wiring Diagram

Hello I am trying to find out the correct way to wire my house for
a Comcast cable TV and modem. I have heard several ways I just want to find the most popular way so my modem functions efficiently and TV has a good signal . Right now I am having a problem with the farthest TV from where the cable comes in to the house about 70'
it works at times and then just cuts out. all connections are tight
I think I just want to start over and need a diagram as to do it correctly. Thanks Mark

At 70 feet you're more than likely losing signal due to line loss. An inexpensive drop amplifier on the split feeding the TV should fix that.

For example: »www.3starinc.com/broadba ··· ier.html

If there are other issues causing your poor reception, an amp can actually make those worse.

You can pay Comcast for an amplifier installation or do it yourself easily enough.

There have been some other recent threads about poor signal levels where you can get some ideas on what you could do:
»Poor picture quality
» Do I need to get an amplifer and active return?

In your case, if your cable modem is located near the cable entrance to your home and it currently has good signal levels, a set-up where you use a high-quality unbalanced 3-way splitter (like the Antronix CMC2003H: »www.amazon.com/ANTRONIX- ··· 01E4T3YK) connected in the arrangement shown below, that provides the strongest signal to the farthest TV, may work out better for you:

                         -7dB output
                          ---> to the Cable Modem
                        / 
---> 3-way unbal splitter -7dB out ---> to other closer TV(s)
                        \
                          ---> 70' cable to the farthest TV
                         -3.5dB output
 

If you wired the house yourself, what kind of coaxial cable are you using - brand, catalog/part number, RG6, RG59, number of shields, etc? And, what about termination fittings? Furthermore, what is the make and model of your splitter? Some splitters are pure junk and may actually cost more than really good ones. You should be able to get two two-way splitters from your local Comcast office for free or flag down a truck and maybe get a three way. My local office didn't have any splitters having more than two outlets when I rewired. Comcast here uses Extreme Broadband splitters, but other regions may use other brands of equal quality. The splitter should have a frequency range of 5 - 1,000 MHz. Two two-way splitters will give you the three outputs as telcodad showed - two -7 dB outs and one -3.5 dB out.

Thanks for your help That what I needed Mark

Yes, if you get only two 2-way splitters (or your cabling arrangement requires two splits in different areas of your home), as Streetlight suggested, here is how to connect them:

                        -3.5dB output
                         ---> 70' cable to the farthest TV
                       / 
--> 1st 2-way splitter 
                       \
                         ---> to 2nd 2-way splitter < Modem and other TV(s)
                        -3.5dB output
 

It's best to avoid using an amp if possible. Unless you have a lot of splits to feed a large number of boxes in your home, you should not need to use one.

If the signal levels are low entering your home, you need to call Comcast about that and have a tech check it out.

If after replacing the splitter(s) and cables with high-quality ones, you still have a signal level issue with the farthest TV, then placing a good-quality bi-directional amp right after that splitter output then may help (you want to avoid using an amp on the cable modem's line). Besides the amp that jack b suggested, you can check out some other ones that were recommended in this thread: »[DVR] Which AMP to use

Thanks for the info Mark