Coax cable question

[Lee Schierer]

In a house with digital cable tv from a cable provider (COMCAST) where splitters are used, do unused outlets of the splitter need special termination caps? If so what exactly are they called? If there is a signal booster with several outlets, do the unused outlets need terminations? I used to know this stuff, but CRS is setting in.

[Jim Becker]

Yes, you should cap unused outlets with readily available coax terminators. They look like little "hats" and you screw them on like a regular connector. If you have a large number of those unused, you should use smaller splitters.

[Lee Schierer]

Yes, you should cap unused outlets with readily available coax terminators. They look like little "hats" and you screw them on like a regular connector. If you have a large number of those unused, you should use smaller splitters.

Splitters seem to come in frequency ranges like 5 MHz - 1 GHz; 5 MHz - 2.3 GHz. which do I need?

[Mike Henderson]

Splitters seem to come in frequency ranges like 5 MHz - 1 GHz; 5 MHz - 2.3 GHz. which do I need?

It depends on what the highest frequency is in your cable system. A lot of cable systems only go to about 1GHz but unless there's a big price difference, I'd go with the higher frequency in case your cable provider upgrades at a later time.

An issue is whether you have any old splitters in the cable path somewhere. Originally, they were about 500MHz on the top end. If you have some of those, you would do well to track them down and replace them.

Mike

[You would do best to only have splitters with the number of ports that you need - no extras. A splitter divides the signal power so too many ports can cause your signal to be low enough that one or more services won't work.]

[Marty Gulseth]

Just a quick comment if I may - you all probably know this, but those splitters are not 100% efficient, they are lossy. So, for a simple one-to-two splitter, you don't get 50% of the original signal level at the split ports, you will get something like 40-45% (or less, for a real cheapy.) As Mike mentioned, this can aggravate things when the system gets too many splitters or too many ports on one splitter and the signals are getting dicey downstream.

(Yes, I am a gEEk and proud of it!)

Regards, Marty

[Jason Roehl]

You're better off doing a couple things: If the outlets are unused, and likely won't be, don't just cap them, get a splitter that only has enough outlets for the number of devices you use. Two, only use ONE splitter off the main service entry cable, don't daisy-chain them. THREE, since this is Comcast, you could try asking for the appropriate splitter at your local office--many times they will hand this type of thing out for free, as it saves them a service call (sometimes you may have to be a little persistent/persuasive, but we've never had any problems with our local Comcast office). While you're there getting a splitter, get any cable you might need to replace any that might be iffy, they should also give that away free (I found this out AFTER I had bought the friction-fit tool, fittings and a roll of quad-shield cable).

[Lee Schierer]

Just to follow up. Thank you all for the information. I was able to eliminate two splitters with multiple outputs with some double male connectors and now the signal reaching the TV is much stronger so it can actually get the internet signal that was missing before. I also capped two outputs with terminators on the signal booster.

Thanks again

Lee

[Chris Padilla]

Just to extend the gEEkiness of all this, the reason you terminate is to prevent signal reflection. The terminator (no, not Ahh-nold) is actually a resistive load and quite probably just a resistor. It will be of the same value of resistance (or more correctly the characteristic impedance) of the cable. Most "coax" in homes is 75 Ohms so the terminator (I'll be baaakk!!) will likely be 75 Ohms. Signal reflection happens every time there is a mismatch or a deviation from 75 Ohms so if it is open (no termination, infinite impedance) or shorted (0 ohms) or even a different cable not 75 Ohms is plugged in, the signal reflects or bounces back in the opposite direction. This is called noise (or more gEEkingly, Return Loss) and something we wish to prevent. A splitter is designed to minimize reflection (but some still happens) but it also absorbs a bit of the signal in its impedance so they never transfer 100% of the signal...there is loss in reflection and its internal resistance (heat). Anyway, all the advice provided here was sound:

Minimize splitters
Use the right number of splitters such that no terminators are needed
Always terminate unused ports