General Question

ETpro's avatar

Cable People: Are splitters really unidirectional?

Asked by ETpro (34208 points ) October 21st, 2012

Most cable splitters are like this one with labels for “In” and “Out”. Are they diode protected and thus unidirectional, or are they actually bidirectional? I want to use one in a non-conventional fashion to help reduce cable clutter. I want the external feed to go into one of the two “Out” connections, and want to route the “In” from the splitter to my TV Cable Box and the other “Out” along the living room wall in the opposite direction, under the threshold, and into my office where it connects to my Internet Cable Modem.

I know I could just test and see if it works. But my wife is sleeping to TV right now, and if the set suddenly goes off from my testing she’ll wake up and rave on for a half hour about how thoughtless I was to interrupt “her program”. So I figured I’d just ask all the cable gals and cable guys here.

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9 Answers

RocketGuy's avatar

A good splitter will take the signal from the “in” and equally split it to the two “outs”. It can also combine the two “outs” and send it to the “in”. Trying to send a signal from one “out” to the other “out” might not work well. Cheap splitters will just have the center conductors soldered together, so “in” and “outs” are all the same.

ETpro's avatar

@RocketGuy Thanks for the “Ins and Outs” of cable splitters. Sounds like I just need a cheap one.

filmfann's avatar

The signal will not be the same quality if used in the reverse direction.

filmfann's avatar

I don’t know the reason, I just know the results. I have tried this, and it doesn’t work well.

dabbler's avatar

@ETpro I might be missing something but why not route the external cable to the “in” and the two “out“s to the internet cable modem and cable tv box ?

That said “Digital… Bi-Directional” helps in this situation because it is made to propagate signals in both directions, absolutely necessary for internet, and even for digital cable tv to work at it’s best. Older splitters do not have this accommodation and definitely do not work as well in both directions.

The ‘in’ signal goes through two independent inductors to get to the two ‘out’s, so going from one ‘out’ to the other ‘out’ sends the signal through two inductors… twice the signal attenuation. Might work but… if it doesn’t then try reconnecting per my first sentence.

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ETpro's avatar

@dabbler What’s the purpose of an inductor? I’d expect splitters to be simple coaxial conductors. used the T shaped splitter as I mentioned to keep the cables routed as I wanted them, and it works just fine.

RocketGuy's avatar

The fancy splitters are designed to adjust the phase of the signals so that they don’t cancel each other out when combined (2 in’s into 1 out). When used as 1 in and 2 outs, the phases are also matched, which some EE’s can take advantage of later.

It cracks me up that some cheapy splitters have the fancy Digital, Bi-Directional name. Those are the ones where all center connections are just soldered together – no fancy electronics inside.

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