Cable splitting question

I recently bought a USB TV Tuner for my computer so it looks like I’m going to split the cable line again to get another signal for it. Here’s my (future) setup: from the main cable jack it will need to be split three times: 1 for my cable modem, 1 for my main HDTV digital cable box, and 1 to go into my future PC TV tuner.

Now I’ve had issues with splitting cables in the past and cable modems. First off, am I going to have any significant problems that would require me getting an amplifier to boost the signal? I figure splitting it just 3 ways probably won’t have much of an effect on me…

Also, what kind of splitter should I get? This site recommends “high bandwidth low-loss splitters” but that’s rather vague… What should the splitters specifically say on it?

As they add more cable channels, including digital & HD, splitting the cable becomes more and more tricky. I had split the cable in my house some years back and had no problems until a while ago. Then some of my channels were coming in all weird.

When the cable guy went through my house he told me right away that some of the splitters from just a few years ago were no longer useful for todays bandwith. And sure enough, it was the splitter that needed to be changed. He put in a different one for free. He also swapped out the splitter that splits the road runner signal so I can use my WIN TV without problems.

Maybe your cable company can recommend/provide the proper splitter?

Most amplifiers to split the signal only amplify in one direction, towards the TV set. They will block the signal in the other direction making duplex communication with the cable modem impossible. Make sure the amplifier is bi-directional, and is the first thing the cable goes through after it enters your residence.

Hmm… I just looked at the splitter the cable installers used when they set my cable and internet up and it says 5-1000MHz and each output says 3.5dB. It’s apparently a “Genesys II” 2-way splitter. Perhaps I could just get a 3-way splitter with the same specs?

Three way splitter will by necessity have a larger dB drop.

This is the three-way splitter Comcast installed when I made a service call about problems with my cable modem.

Thanks for the input everyone! I just ended up getting a 4-way bi-directional powered RF amplifier that seems to be working great…

And now for a related question… For my PC tuner card, it has one coax input. It’s currently hooked up to my (analog) cable signal so I get all the basic cable channels on it. Would it be possible to hook that signal, along with a signal from an antenna (that was included to pickup over-the-air HD signals) into a combiner and have the output of that go to the tuner in order to get both normal cable channels plus local channels in HD? Is my concept of a combiner correct here?

I don’t think so. There’s a substantial overlap between OTA broadcast channels and the channels used in a cable system.

SDMB, we have a problem. I thought the new splitter/amplifier was doing a good job but ever since I got it I’ve been having occasional internet problems. I’ll have internet access, then all of a sudden, my internet is gone. I’ll tell Vista to “Diagnose and Repair” the problem and this is the error message it always spits at me:

Does this sound like a problem with the amplifier? Here’s a pic of the old 2-way splitter I was using (without problems) from the cable company:

Here’s a picture of the bi-directional RF amp I’m currently using:

The configuration: the IN line is coming straight from my coax wall jack, OUT 1 is to the cable modem (and then to router), OUT 2 is to digital cable box, and OUT 4 is to computer’s TV tuner. Did I get an amp with unsuitable specs? What could be causing the rather random internet connectivity loss (that seemingly fixes itself after a few minutes)?

This is substantially the hookup I have with my HDTV - I use a simple switcher to go between analog cable and digital broadcast.

HOWEVER… to do it I need to flip the tuner selector on my TV from cable to air. If your tuner card is designed for cable only, you’ll be SOL.

I’m not sure how it’d work with internet stuff, but sometimes, when I deal with splitters with work, I find the Eagle Aspen, and Holland brand splitters work well, with a slight preference for the former. They typically work with frequencies above 2000MHz, so they should be adequate for most applications where a splitter is appropriate. My guess is that one marked ‘all ports power passing’ would be what you’d want, but perhaps someone else in here might know better than I…

After reading a bit on the interwebs, it seems one of these splitters should be adequate…


Sounds like the problems I was having about 2 weeks ago. We moved our computers to a different room, so the cable modem was plugged into a different cable jack. The internet connection would be fine, and then disappear. A couple of minutes later, it would be back. It turned out that the signal strength to the modem was borderline being strong enough. If there was any kind of waver in the signal, the stength would dip below the minimum required and we would lose connection. Try unplugging other equipment that is hooked into your cable jacks. Unplug them at the wall, not from the cables. I found that one cable/splitter combo, down in the TV room, was enough to drop the signal, even if there wasn’t a TV connected to it.

Then, call your cable company and have them add line-guarantee, or line-backer or whatever they call it, to your account. It runs $3/month where I am. Normally the cable company is only responsible for the cable until it hits the wall of your house. The line-guarantee is their fee to cover lines inside the house. Now, call the cable company and tell them that you have a low signal strength to your modem. Set up an appointment for them to come out. While you are waiting, remove any cable splitters that you have installed.

For us, the cable repair guy rerouted one of the cables in the wall. He also replaced all of the wall-to-equipment cables and gave us a couple of cable splitters. All for the $3 monthly fee.

After everything is fine, call the cable company and cancel the line-guarantee. Yes, they know it happens. When I called with my original low-signal problem, the person I talked to asked “Do you want to add line-guarantee? It’s $3/month and you can cancel at any time.”

Try looking at the signal levels if your modem has a built-in web server. Search for your modem model number and “signal levels” on your favorite Google-like search engine.