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#173233 - 01/05/08 04:43 PM Coax as network cable
Obsaleet Offline
Member

Registered: 04/05/03
Posts: 361
Loc: Pa
Does anyone know if I can use a coax cable to extend my existing network?

Ob
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#173236 - 01/05/08 05:33 PM Re: Coax as network cable [Re: Obsaleet]
TOOL_5150 Offline
Member

Registered: 08/01/07
Posts: 62
Loc: Bay Area
You cannot. You need at least 2 pairs to have ethernet work.

~Matt
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#173237 - 01/05/08 06:06 PM Re: Coax as network cable [Re: TOOL_5150]
techie Offline
Member

Registered: 05/17/05
Posts: 240
Loc: palo alto, ca usa
 Originally Posted By: TOOL_5150
You cannot. You need at least 2 pairs to have ethernet work.

~Matt


This is true if you are using twisted-pair based ethernet (10baseT, 100baseT, 1000baseTX), but remember that the original 10mb ethernet was based on a single coax cable bus running between stations, tapped at each location.

Coax is not used for new installations, but it is still out there. It's generally considered to be obsolete, but it still works if you don't expect high performance.

Coax based ethernet is 10mb/sec, shared media, half-duplex, unlike 10baseT which uses dedicated tx/rx paths, and can be full-duplex if connected to switches.

Coax based ethernet comes in two types. ThickNet (10base5) uses a thick 50ohm coax similar to RG8/RG213/RG214 type. Normally yellow or orange in color, tapped with vampire taps, or N connectors. Maximum segment length 500m before a repeater or bridge is required. Each end must be terminated with a 50ohm terminator.

ThinNet (10base2) uses RG58A/U type 50ohm coax, with a maximum segment length of 185m. BNC connectors and T's are used at each station. Each end must be terminated with a 50ohm terminator, which may be built-in to a hub.

Note that these are both 50ohm coax types, not the 75ohm coax used for tv/sat/video.

If you are using a 10mb hub with a BNC connector on it, you can use RG58A/U to extend the network to other hubs.

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#173238 - 01/05/08 06:23 PM Re: Coax as network cable [Re: techie]
TOOL_5150 Offline
Member

Registered: 08/01/07
Posts: 62
Loc: Bay Area
You still use that junk? I figured 2 things when answeing this question: He isnt going to want to buy a bunch of obsolete junk to make that work, and he is probably talking about RG6. However - good point techie.

Hey Obsaleet, Can you use the existing coax to pull in a cat5 cable.

~Matt
_________________________
I would rather beg for forgiveness then beg for permission.

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#173239 - 01/05/08 06:47 PM Re: Coax as network cable [Re: TOOL_5150]
Obsaleet Offline
Member

Registered: 04/05/03
Posts: 361
Loc: Pa
Thanks guys,
I don,t 10mb is gonna cut it. I have an sub building that was wired in 1969. Someone has run coax to it. The old phone lines have been spliced many times from what I can see. All is direct buried about 200'. We tried a new product that is like a DSL but I think there is to much impedance on the phone lines due to the splices. It did not work. The wireless is not reliable and security is now becoming an issue do to change in use. I 'm working up a price to get a 2" pvc coduit out there and due it proper. I'm getting concerned about distance thou as the trench will have to go the long way around(about 280"). As usual the budget is tight.

Ob
_________________________
Choose your customers, don't let them choose you.

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#173240 - 01/05/08 09:10 PM Re: Coax as network cable [Re: Obsaleet]
techie Offline
Member

Registered: 05/17/05
Posts: 240
Loc: palo alto, ca usa
Sounds like you are going to want to run fiber..

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#173242 - 01/05/08 09:20 PM Re: Coax as network cable [Re: TOOL_5150]
techie Offline
Member

Registered: 05/17/05
Posts: 240
Loc: palo alto, ca usa
 Originally Posted By: TOOL_5150
You still use that junk? I figured 2 things when answeing this question: He isnt going to want to buy a bunch of obsolete junk to make that work, and he is probably talking about RG6. However - good point techie.


I support a small network that has a run of thicknet out to a remote communications shelter to support a pc and a multiport terminal server used to interface to a antenna positioning system.
The distance is too far for twisted-pair, and thicknet cable was readily available, as were 10mb hubs and utp-to-coax media converters. The required bandwidth is low.

Around here, getting your hands on obsolete 10mb hardware is easy.. you just take a run down to Weird Stuff, or any of the other surplus places in the valley.

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#173243 - 01/05/08 10:42 PM Re: Coax as network cable [Re: techie]
TOOL_5150 Offline
Member

Registered: 08/01/07
Posts: 62
Loc: Bay Area
Oh.. didnt see where you were. You talking about the one on Caribbean Dr? I have been to that one and their first location as well.. the newest place seems to be the biggest warehouse they have. I live in antioch.

You must know of halted too then, right? That place always beat weird stuff imo.

~Matt
_________________________
I would rather beg for forgiveness then beg for permission.

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#173244 - 01/06/08 01:28 AM Re: Coax as network cable [Re: TOOL_5150]
techie Offline
Member

Registered: 05/17/05
Posts: 240
Loc: palo alto, ca usa
Thats the one..

HSC has a better selection of some things, but Weird Stuff has more computer stuff. HSC always seems a bit overpriced..

The one I miss is Haltek, which had a great selection of small hardware (screws, etc) and linear power supplies. (they had a large stack of Lambda supplies..), but they closed a number of years ago.

The other good place to get parts, although they are not a surplus house, is HDB in Redwood City. There is a good taco stand down the street as well.

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#173255 - 01/06/08 09:26 AM Re: Coax as network cable [Re: techie]
Obsaleet Offline
Member

Registered: 04/05/03
Posts: 361
Loc: Pa
Techie,
It was my understanding that 300' would be the cutoff. I would expect that even if we are close we will just have less bandwidth. Witch compaired to what is going on now would be a hughe improvment.


ob
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