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Running ethernet over Van Damme 268-307 6 x 75 ohm cable

Started by Peter October 13, 2019
Hello All,

For complicated reasons I have this cable in place. It was installed
20 years ago and is inaccessible except at the ends. Total length is
about 20m.

I have not found data on it but there is a 268-307-20 which is a
single core 75 ohm coax and this one seems to have six of these, plus
what looks like smaller (audio type) coaxes.

It looks like a professional video cable.

I need to send ethernet over it.

I know one can run ethernet over a 50 ohm coax using an RJ45 to coax
media converter. These are common and cheap. And one could convert 50
ohm to 75 ohm with adapters which presumably just contain a
transformer.

But that gives you only 10 megabits/sec. That is only just barely
enough for media (video) over ethernet.

How could I get say 50 megabits/sec? Or possibly standard 100mbps?

Any ideas much appreciated.
On Sun, 13 Oct 2019 15:10:23 +0100, Peter <nospam@nospam9876.com>
wrote:

>Hello All, > >For complicated reasons I have this cable in place. It was installed >20 years ago and is inaccessible except at the ends. Total length is >about 20m. > >I have not found data on it but there is a 268-307-20 which is a >single core 75 ohm coax and this one seems to have six of these, plus >what looks like smaller (audio type) coaxes. > >It looks like a professional video cable. > >I need to send ethernet over it. > >I know one can run ethernet over a 50 ohm coax using an RJ45 to coax >media converter. These are common and cheap. And one could convert 50 >ohm to 75 ohm with adapters which presumably just contain a >transformer. > >But that gives you only 10 megabits/sec. That is only just barely >enough for media (video) over ethernet.
A decade or two ago, there was some hype about running 10 Mbit/s Ethernet across a single 75 ohm MATV/CATV cable. In 10 Mbit/s the carrier sense and collision detection (CS/CD) was well defined.
>How could I get say 50 megabits/sec? Or possibly standard 100mbps?
If you have two 75 ohm coaxials, then you can forget the CS/CD issue and run unidirectional links in each cable. Twisted pair to 75 ohm coaxial using baloon transformers should do the trick.
> >Any ideas much appreciated.
On 13.10.19 17:10, Peter wrote:
> Hello All, > > For complicated reasons I have this cable in place. It was installed > 20 years ago and is inaccessible except at the ends. Total length is > about 20m. > > I have not found data on it but there is a 268-307-20 which is a > single core 75 ohm coax and this one seems to have six of these, plus > what looks like smaller (audio type) coaxes. > > It looks like a professional video cable. > > I need to send ethernet over it. > > I know one can run ethernet over a 50 ohm coax using an RJ45 to coax > media converter. These are common and cheap. And one could convert 50 > ohm to 75 ohm with adapters which presumably just contain a > transformer. > > But that gives you only 10 megabits/sec. That is only just barely > enough for media (video) over ethernet. > > How could I get say 50 megabits/sec? Or possibly standard 100mbps? > > Any ideas much appreciated. >
If you can use two cables, a 100 Mbit/s connection should go fine using one cable for uplink and the other for downlink. At least here (Northern Europe), there are TV antenna adapter cables with a RJ-45 at one end and a 75 ohm coax connector at the other end (and a balun inside). You'll need some RJ-45 connectors to branch the pairs to the adapters at each end of the link. -- -TV
upsidedown@downunder.com wrote

>>How could I get say 50 megabits/sec? Or possibly standard 100mbps? > >If you have two 75 ohm coaxials, then you can forget the CS/CD issue >and run unidirectional links in each cable. Twisted pair to 75 ohm >coaxial using baloon transformers should do the trick.
That is above my pay grade; I know analog but know almost nothing about the way ethernet (RJ45, 8 wires) communicates.
Peter <nospam@nospam9876.com> wrote:
> Hello All, > > For complicated reasons I have this cable in place. It was installed > 20 years ago and is inaccessible except at the ends. Total length is > about 20m. > > I have not found data on it but there is a 268-307-20 which is a > single core 75 ohm coax and this one seems to have six of these, plus > what looks like smaller (audio type) coaxes. > > It looks like a professional video cable. > > I need to send ethernet over it. > > I know one can run ethernet over a 50 ohm coax using an RJ45 to coax > media converter. These are common and cheap. And one could convert 50 > ohm to 75 ohm with adapters which presumably just contain a > transformer. > > But that gives you only 10 megabits/sec. That is only just barely > enough for media (video) over ethernet. > > How could I get say 50 megabits/sec? Or possibly standard 100mbps? > > Any ideas much appreciated.
You can solve this using MoCA. These are adapters to run ethernet over in-house COAX installations made for TV. Different levels exist that can do 100 Mbit/s and even like 500 Mbit/s. 20m is no problem. I ran this for a while on a cable like 150m long, and it worked perfectly.
Rob <nomail@example.com> wrote

> >You can solve this using MoCA. >These are adapters to run ethernet over in-house COAX installations >made for TV. >Different levels exist that can do 100 Mbit/s and even like 500 Mbit/s. > >20m is no problem. I ran this for a while on a cable like 150m long, >and it worked perfectly.
Thank you. I bought a couple of IB-CX110-110-KIT and will see how fast they run. I would like to run some videos which were encoded at 30-50mbps and these absolutely do not run over wifi no matter what the wifi is. Even "5 gigabit" wifi doesn't keep up, though probably because the 5Gb signal is usually so weak that normal 2.4Gb wifi runs faster ;)
Peter wrote:
> Hello All, > > For complicated reasons I have this cable in place. It was installed > 20 years ago and is inaccessible except at the ends. Total length is > about 20m. > > I have not found data on it but there is a 268-307-20 which is a > single core 75 ohm coax and this one seems to have six of these, plus > what looks like smaller (audio type) coaxes. > > It looks like a professional video cable. > > I need to send ethernet over it. > > I know one can run ethernet over a 50 ohm coax using an RJ45 to coax > media converter. These are common and cheap. And one could convert 50 > ohm to 75 ohm with adapters which presumably just contain a > transformer. > > But that gives you only 10 megabits/sec. That is only just barely > enough for media (video) over ethernet. > > How could I get say 50 megabits/sec? Or possibly standard 100mbps? > > Any ideas much appreciated. >
Obviously, use a faster converter..the 100mbps one.
On 2019-10-13, Peter <nospam@nospam9876.com> wrote:
> Hello All, > > For complicated reasons I have this cable in place. It was installed > 20 years ago and is inaccessible except at the ends. Total length is > about 20m. > > I have not found data on it but there is a 268-307-20 which is a > single core 75 ohm coax and this one seems to have six of these, plus > what looks like smaller (audio type) coaxes. > > It looks like a professional video cable. > > I need to send ethernet over it.
the cable guys do network over 75 ohm cable.
> I know one can run ethernet over a 50 ohm coax using an RJ45 to coax > media converter. These are common and cheap. And one could convert 50 > ohm to 75 ohm with adapters which presumably just contain a > transformer. > > But that gives you only 10 megabits/sec. That is only just barely > enough for media (video) over ethernet. > > How could I get say 50 megabits/sec? Or possibly standard 100mbps?
if you can use one coax for up and one for down all you need is the right baluns at each end, the balun trnsformers are going to need to pass 5 to 70Mhz at about about 80mW power. (you need the 5Mhz capability for the neotiation of fast ethrnet which uses faster symbol rate. transforming 100 to 75 ohms calls for a turns ratio of 2:sqrt(3) so a 7:6 ratio is pretty good.. The transfomers in a VGA to twisted pair adaptor might work, VGA is 75 ohms and SXGA is about 150HHz pixel rate so there should be enough bandwidth at the high end. -- When I tried casting out nines I made a hash of it.
On 2019-10-13, Peter <nospam@nospam9876.com> wrote:
> > upsidedown@downunder.com wrote > >>>How could I get say 50 megabits/sec? Or possibly standard 100mbps? >> >>If you have two 75 ohm coaxials, then you can forget the CS/CD issue >>and run unidirectional links in each cable. Twisted pair to 75 ohm >>coaxial using baloon transformers should do the trick. > > That is above my pay grade; I know analog but know almost nothing > about the way ethernet (RJ45, 8 wires) communicates.
at 100Mbit/s (100 Base Tx) one pair the signal outwards and another carries the inwards signal, and the other 4 conductiors do nothing at all. So you just need to interface the twisted pair tp the coaxial in such a way that the signal integrity is maintained. that where balun transformers come in. -- When I tried casting out nines I made a hash of it.
Peter <nospam@nospam9876.com> wrote:
> > Rob <nomail@example.com> wrote > >> >>You can solve this using MoCA. >>These are adapters to run ethernet over in-house COAX installations >>made for TV. >>Different levels exist that can do 100 Mbit/s and even like 500 Mbit/s. >> >>20m is no problem. I ran this for a while on a cable like 150m long, >>and it worked perfectly. > > Thank you. I bought a couple of IB-CX110-110-KIT and will see how fast > they run. > > I would like to run some videos which were encoded at 30-50mbps and > these absolutely do not run over wifi no matter what the wifi is. Even > "5 gigabit" wifi doesn't keep up, though probably because the 5Gb > signal is usually so weak that normal 2.4Gb wifi runs faster ;)
Ok, this is not MoCA but it will likely work just as well. You will find that such solutions much better than WiFi. MoCA has the advantage that it uses a radio band outside the normal cable bands so you can run cable TV and network at the same time over the same cable. When that is not required, a converter like you have chosen should work just as well.