Q: What kind of splitter do I want?  
A: If you can flag down a cable guy and convince him to give you some free splitters, then good for you. If you can't, then be prepared to spend some money.

Those cheap looking splitters they sell at Radio Shack are NO GOOD. Do NOT use combiner/splitters. Combiners trash digital signal and make it almost impossible for cable modems and digital boxes to talk back to your provider.

You want at least a 1GHz splitter. 900MHz usually work as well (unless your cable company actually goes above a gig, which I seriously doubt).
The 1GHz means that the splitter is designed to pass signals all the way up to 1GHz.

You may also have the option of buying power passing or not. You most likely do not need a power passing splitter. These are generally for special purpose applications (such as powering a signal amplifier that's in your attic from the outlet in your bedroom without running a power cord to it).

Also, do not get a bigger splitter than you NEED. The more ports a splitter has, the less signal it passes along to each port. Plus, they are more expensive.

Splitters are NOT made to connect wires together. I've been to many houses where people used an old crappy splitter they had laying around to hook up 2 or more short wires to each other because they didn't want to go out and buy a longer wire. SPLITTERS LOSE SIGNAL.

Good brands that I personally have dealt with are Monster (expensive), Regal, and Cablevision. I'm not incredibly fond of Magnavox splitters (usually found at K-Mart).
 
 
Q: What is the best configuration for my splitters for TV service?  
A: Basically, you want to even out the signal distribution as much as possible between all of the TVs.

If you have a loop system, there isn't much you can do, but if you have a junction, spend a few minutes looking at the numbers on the splitter and see what you can come up with.

Remember that cable loses signal over distance.
 
 
Q: What's the best configuration for HSD with two other TVs?  
A: You should have a 3 way splitter here. Put the modem on the 3.5db leg of the splitter, and the TVs on the 7db legs.
 
 
Q: What's the best configuration for HSD with three to four other TVs? 
A: Usually you'll have a two way splitter at the top, with one 3.5 leg going to your cable modem. The other 3.5 leg will go to either a 3 or 4 way splitter, depending on your needs.
 
 
Q: What's the best configuration for HSD with five to six other TVs?   
A: In this case I'd usually use a three way at the top.
The 3.5 leg on the first three way will go to a four way. The first 7 leg would go to the cable modem, and the second 7 leg would go to any TV.

The 3.5 and 7 leg can be swapped if the cable modem doesn't like it, but your TVs might be getting a little fuzzy at this point.

After 6 TVs, an amplifier is usually a good idea.
 
 
Q: What's the best configuration for HSD with seven or more TVs?   
A: This one is easy:

A two way at the top, one leg going to the cable modem, and the other going to an 8 way. Cable modems do NOT like 8 way splitters, so try and keep it away.

You will most likely need an amplifier in order to have decent TV service (or you can just have some of your unused outlets turned off).
 
 
Q: Why don't you discuss 5, 6, 10, or 16 way splitters?   
A: Mostly because they are not common. Although there are some situations where these rare splitters will fit in great, you'd probably have to order them online or from a special supply store.

You can do a pretty good job by just using 2, 3, 4, and 8 way splitters.
 
 
Q: What do the numbers on a splitter mean?   
A: Each splitter is different, but here is what most of them mean:

The numbers on each OUT leg of the splitter show how much signal is lost after passing through that leg.

For example, a 2 way splitter has 3.5 on each leg. That means that 3.5db was lost as the signal passed through that leg.

Note: The signal loss written on splitters is how much is lost at around 50 to 100Mhz. The higher a frequency is, the more is lost over distance. This applies to splitters too. In reality, a cable modem is probably losing more like 4 to 5db when passing through this same splitter.

The following info provided by RadioDoc:
On the back of a splitter, you may see a number like 130db EMI etched into it. That's the ingress/egress suppression (shielding) spec for the splitter, e.g. if a +10 dBmv signal is present inside at the input, the maximum leakage from the splitter itself would be 10-130=-120 dBmv, which is very low. Same the other way...
 
 
Q: What's the difference between a Passive and an Active Splitter?  
A: Passive Splitters are the ones you see every day. They have an "In", and 2 or more "Outs". You hook them up, they do their thing, and you never touch them again. They do not require any kind of power to run.

Active Splitters run on power. Most active splitters also boost the signal a tiny bit to compensate for the signal that would usually be lost after passing through a passive splitter.

Do not confuse an Active Splitter with an Amplifier.
 
 
Q: Why did the installer put a 2-way split on my CM? 1 is open.   
A: You may have been getting too MUCH signal. We do this sometimes to lower the amount of signal you are getting.

Also, he may have just been trying to be nice by leaving something you can plug your TV into.

  or he/she (Tech) was out of barrels.
 
 
Q: Is it important to use a terminator on a unused splitter output?  
A: This really can depend on your system and the type of splitter that you are using.

  we use terminators for three reasons:

1.) To prevent ingress from entering the system through an open port at the tap.
2.) To prevent signal reflections (which really isn't too big of a problem).
3.) To prevent cable theft.

Honestly, I doubt it would make much difference to have a terminator on a splitter in the home. If you want to do it anyway, you may be able to pick up a pack or something from Radio Shack.

You cannot use the ones that cable companies use, because they require a special tool to install/remove them (prevent cable theft).

Please see the definition for terminators for pictures of them.
 
 
 
 
Q: How can I configure 17 seperate outlets? 
A: I'm Going To Be Wiring My Home W/ (Wall Plates) RG6 In 8 Rooms
2 Per Room(In Case We Move TV To The Other Side Of Room), So 16 Splits + A Cable Modem

What's The Best Way To Do This?
Will I Need Terminators On The 8 Unused Splits,
Should I Terminate At The Splitter Or The Jacks?

This is a special situation and I highly recommend you get a 2 port AMP from your cable company.

My suggestion: Input going into 2 way splitter, one which goes to the cable modem, and the other going into the 2 port amp, and each port of the amp going into an 8 way splitter. This is of course if you want to have all 17 outlets active at once.

If you're just going to have 9 active, just use a one port amp going to a single 8 way. In this case you might not even need to use an AMP, depending on how strong of a signal the cable co pushes into your house.

 
 
Q: How do I connect 2 cable modems to a 3-way splitter. 
A: The options are really limited here, so just plug one into the 3.5 leg, and the other into a 7 leg.