star coax network with rj adapters ?


Two years ago, I bought a house that already had coaxial plates installed on almost each rooms. Each plate uses a single wire (no T conectors are used), which makes the whole installation a physical star coaxial network.

Of course, unless I plan to buy 18 TVs and put them everywhere in my house, this setup is kind of useless. However, if I could use these coax wires as an ethernet network, it could help me transform my not- so-reliable wireless computers network to a fast reliable wired network.

I've found RJ-to-coax adapters that seem to be able to do the conversion. But, as a certified CISCO administrator, my knowledge of coaxial wires consist of knowing that they have been used an eternity ago in physical bus topologies barely reaching 10mb with a lot of instability.

So if I put these physical rj-coax converters, will I be able to reach fast ethernet speeds and standards? Will the coax wires ever be able to reliably support a lan-type computers network?

Thank you, EBL

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Assuming you want to use 10/100 Base-T over these "physical RJ-coax converters", how do they provide conversion of 2-conductor coax to 4-conductor twisted pair ??

Any chance the coax can be used as "pull string" for CAT5 wire ??

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What kind of connectors on the plate? Screw-on ~ 3/8" diameter normally used by TVs (type 'F' connector)? BNC?

If that is for television, it's almost certainly RG-6/U or RG-59/U coax, which is 75 Ohm. Ethernet uses cables similar to RG-8/U (for the original thick-net) or RG-58/U (thin-net) both of which are 50 Ohm. That means Ethernet doesn't work to well (if at all) using television coax.

Not very likely. The cables come together somewhere (the "center" of the "star" using splitters - which are basically resistor networks to "match" the impedances. These will not work on Ethernet.

There were media converters that allowed connecting coax to one (or more) twisted pairs. These worked for 10Base5 (Thicknet) or 10Base2 (thin-net) ONLY.

That would come as a bit of a surprise to Bob Metcalfe who co-invented Ethernet, and founded 3Com. It might also surprise a few people who were using coax networking for a dozen or more years.


They did for years - but not using the configuration you have.

Google for 'media converter'. For the simple minded, think of a

10Base2 NIC connected back-to-back with a 10BaseT NIC.

If the coax is in conduit - perhaps. More often, the coax is secured to internal wall support structure (studs) with staples or bent nails.

Old guy

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Moe Trin

having lived thru StarLan and ArcNet - along with IBM mainframe 3270's it's always interesting to stumble across coax related discussions.

Depending upon what you have found to "convert" the coax into 10baseT, you might not be looking at the right stuff....

We used to use coax to twisted pair "baluns" for the IBM 3270 terminals, to run the coax terminals across the internal twisted pair phone wires....

You are looking at the other way around - you need to have TWO pairs of signals - xmt & rcv - going across the coax. That would seem to indicate that an "active" device would need to make the transformation from the RJ-45 based Ethernet to the single conductor based coax.

Worse case - you would need; xmt, rcv, common ground - 3 conductors - the coax has center + shield = 2 Therefore, a plain direct connect RJ45 solution won't seem to work, it would appear you need something that puts a "signal" on the coax - xmt channel + rcv channel ?

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A very common device in the 10Base? era was a hub - specifically one that came with two or more interface types - 10BaseT, and 10Base2 coax and/or AUI. It was a simple matter to plug in your twisted pair on one side, and use the appropriate interface on the other. These would probably be considered a repeater, but as we commonly used them to connect those systems that only had a 10BaseT interface to our coax network, under the worst case, there would be two repeaters between the furthest hosts on the wire.


Results 1 - 10 of about 157,000 for Ethernet hub 10Base2. (0.28 seconds)

Results 1 - 10 of about 97,300 for Ethernet hub 10Base5. (0.27 seconds)

And how did the original Ethernet work? ;-)

Old guy

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Moe Trin

interesting reading guys...

but notice - the OP never came back :)

so we don't really know what he had, or what kind of RJ adapters or media converters he was looking at...

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Hello all,

First, thank you for all your answers. Really sorry to come back so late on that topic but I had to hold my projects for several weeks.

OK, here it goes for the questions you've asked :

1- My home network consists of 8 RG6 individual coaxial runs. 2- The adapaters I found are about 25$/piece ... so with a cost of 50$/ run, the whole project would cost around 400$ 3- Using the existing coax cables as "pull string" for LAN wires or passing new LAN wires on the walls are impossible ; it would ask me to open several walls and, shortly after, negociate an expensive divorce with my wife

From your readings, I understand that the physical properties of RG6 wires are incompatible with fast-ethernet requirements and that those cables were used during base-2 and base-5 era, where physical networks were in bus configurations.

I decided to go for another strategy. I recently moved my phone number on cable-modem technology, along with my Internet connection. Since I am using wireless phone units connected to a single phone base (which connects to my modem), my house phone wiring is completely unused. I will therefore use these 2-pairs wires for fast ethernet.

The only thing I havent figure out yet is where is the phones patch- panel. I suspect the company put all terminations in a locked box, outside the house.


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wrong idea again -

You seem to have this concept that just because you have access to a "wire" that it will serve just about any purpose.... WRONG

Why do you think they are all different to begin with ???? Can you run your TV from the coax thru the "telephone wires" and connect to a TV ?

Each "wire" has it's own set of attributes or properties that makes it work for a given application...... coax, Cat5, telephone twisted pair It's doesn't work like on TV where they tie knots in fiber optic to wiretap..

OK ? do you get it ?

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Hey bozzo,

Read my post correctly. If you don't know that a 2-pairs wire (like those used for voice) also supports data, go read more on networking.

And for you information, wires are *not* made for *given* application. In all standard models (like OSI), layers are independant and a physical specification (like a 2-pairs wire) can support more than one higher specifications.

OK? Do you get it?

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let us know when it all starts working for ya -

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