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So, I've just bought a house. It's reasonably new - built in the early '00s. One of the features that got built in was a cable TV drop in every room. The cabling is gorgeous - there's even a wiring cabinet of sorts in a closet where the cables all tie together to the splitter to the outside line.

Of course, my problem is that I only own the one TV. I do, however, own a few computers. What I would love to be able to do is drop a switch in the wiring closet and run 100/1000BASE-T ethernet over the coax in the walls I wouldn't otherwise be using. My fantasy would be if you could get some kind of adapter-plug-thing that would take a coax plug on one side and a cat5/RJ45 plug on the other.

Had anyone else done this? Any suggestions?

(There are a few other options that suggest themselves - first, I could just use the existing cabling channels and re-run cat5 or 6 through the walls. While tempting, that sounds like more work than I really want to put in, so I'm calling that Plan B. Also, I could just scare up a mess of old 10BASE2 cards and run the house on thinnet, all mid-90s style. While I think I'd get major style points for that, I don't think I can get a 10BASE2 adapter for the new laptop. Also, I have all these super-snazzy gigabit adaptors I'd like to be using. And so forth.)

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+1 for the general enthusiasm and for taking us back to the thinnet-Napster-RealPlayer nineties, if just for a second – trolle3000 Mar 4 '10 at 4:34
up vote 7 down vote accepted

I really think you should go with plan B, as this'll give a lot less problems later on.

It might take some time to install it, but this is only a one-time installation.

Using standard connectors completely makes it easier to ugrade/expand/repair your network later on.

There are some nice connector shields out there that have coax+ethernet connections, enabling you to simply plug in a standard cable anywhere in the house.

also, if you ever want to sell the house, it is worth more, as it has the cables already ;)

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After doing more research, I have to agree. As teabot points out it can be done - just at $200 a pop. Compared to spending a weekend slinging 50 bucks worth of cat5, I think I'll go with Plan B. – Electrons_Ahoy Nov 12 '09 at 18:20

Netgear offer 270Mbps Ethernet-over-coax adapters (MCAB1001) for under $200. They can (apparently) coexist with your cable system (if you have one) and provide a 10/100baseT (RJ45) socket to connect to your LAN/computer.

Not sure what the deal is regarding the advertised 270Mbps transfer speed being limited by the 100bT connection though.

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Damn. Not cheep, but da-amn. – dmckee Aug 3 '09 at 21:45
Wow, those are pretty slick. Still, compare those to the price of vanilla cat5 at monoprice, and the right choice becomes clear. – Electrons_Ahoy Nov 12 '09 at 18:19

In addition to what others said: TV coax is not the same as 10baseT coax. The former has an impedance of 75 Ohm (at least in Europe) the latter has 50 Ohm.

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It's a nitpick, but 10baseT is not coax. By definition it's twisted pair (that's what the T at the end stands for). What you're referring to as "10baseT coax" is actually 10base2, a true coax, usually of the RG-58 variety, terminated with BNC connectors. – hotei Sep 9 '10 at 20:09

There is a trade body Moca which has this page with a number of ethernet to coax bridges on it. I think this is what you want. However most of them don't look like they are retail products at the moment.

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The Netgear adapter mentioned here… appears to be a result of this Moca trade body. – Martijn Heemels Aug 4 '09 at 9:07

This is not really a serious suggestion...just a dumb, but potentially cool hack.

The cable companies more quite high bandwidth internet activity over 75 ohm coax using only part of the available bandwidth. SO the hardware for this has got to be available, and a standard cable modem is one half of it (and I own two of the things, how about you?). You might even be able to configure several in a peer-to-peer mode with fixed IP address.

Like I said, not serious.

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Man, that is a cool idea. Sadly, I've been a DSL man for the last decade, or I might actually give that a whirl. – Electrons_Ahoy Nov 12 '09 at 18:17
For what it's worth this solution is nearly 30 years old. Look up Sytek cable modems. We networked with them in our office around 1982. – hotei Sep 9 '10 at 20:14

The only option I have seen is a product call TVNet from Coaxsys, but it looks like the product and the company no longer exist. These essentially created an Ethernet transceiver and used some sort of proprietary protocol to communicate over coaxial cable.

Maybe you can find some old units on Ebay.

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There's another alternative that I'm surprised nobody else has mentioned: just install WiFi. If you need multiple connections in one room, you can save on wireless adapters and configure a router running DD-WRT (or your favorite open router firmware) to bridge your wired and wireless networks.

In some houses, it's not easy to run new cable. If that's the case, you can tape the end of your network cable and the end of a rope to the end of the coax in your wiring closet, then pull on the other end of the coax until the network cable and rope are through. To pull the coax back into place, retape just the rope to the coax then go back to the wiring closet and pull until the coax is back. Note that you may or may not have perfect success with this, depending on whether the holes for the cable are big enough to accommodate both coax and network cable, so it might be best to try it first in a room where you'll never need coax (just in case you can't pull the coax back through from the room to the wiring closet).

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There's a cheap solution to your problem that nobody has mentioned so far. The ActionTec that are provided by Verizon implement MoCA, which is a standard that allows IP traffic to coexist with CATV traffic on the same coax. (The speed is good - it should be close to 100baseT wired speed). These routers can be configured in bridge mode, so you can use several of them - you'll need one at each endpoint.

These devices (ActionTec MI424WR) can be bought very cheaply on eBay; I've seen them as low as $25/each. So it should be possible to do exactly what you want without spending a fortune and without causing any problems with your TV reception.

More detailed info can be found in these threads:

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Outside of all these fine suggestions, i'd lurk on AT&T UVerse forums and see what you can dig up.

I just had an install, and the tech tried to use the existing cabling to make my UVerse home net, but we couldn't ever find how to sever from the rest of the building so he just switched to the existing phone networking (forgot to ask if it was cat5).

So, AT&T folks know how to run home ethernet on normal 'cable' coax.

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