The center conductor of the coax is acts a small broadcast antenna (as
well as a receiver) the outer shield serves to contain the signal on the
center conductor to prevent both radiated signal leakage and reception
of over-the-air signals. The exposed end of the cable or splitter
connection is breaks the "seal" on the system and allows for leakage and
reception of unwanted signals. The terminator acts like a lid on jar and
maintains the cables impedance.




" A caveat --

In a setup such as yours, each unused outlet should have a 75 ohm
terminator. Radio Shack has them. Unterminated cables can mess up
the signal to the active devices on the network.

SJF

That goes for any unused connections on the spliter(s) as well. "

Wow, for someone who is regulary considered by his friends as a more
or less maven, I now feel unbelievably ignorant ): I guess ignorance
is relative... I have never heard of 75 ohm terminators, nor of the
problems caused by unterminated cables and unused connections on
splitters. As I mentioned in another response - learn something new
every day.