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

[Peter]

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.

 

[Peter]

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.

 

[Tauno Voipio]

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

 

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.

 

[Peter]

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

 

[Rob]

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.

 

[Robert Baer]

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.

 

[Jasen Betts]

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.

 

[Jasen Betts]

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.

 

[Rob]

Robert Baer <robertbaer@localnet.com> wrote:

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.

The original coax ethernet is only 10 Mbps. Some hardware for that
standard may still be in junkboxes or found as surplus, although a
converter between coax and UTP was never common. There were hubs
that had coax and UTP ports, however.

Today, proprietary converters exist that put 100 Mbps ethernet on coax,
made for the video surveillance camera world where old coax-connected
cameras are being replaced by IP cameras, and it can be attractive to
re-use the existing wiring, especially for outdoor cameras.

 

[Rob]

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.

 

[Dimitrij Klingbeil]

On 2019-10-14 11:04, Rob wrote:

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.

Sorry if this a little off-topic, but has anyone here tried to run WIFI
over coaxial cable in a point-to-point configuration?

Presumably, a coax not rated for 2.4 GHz will add a lot of attenuation,
but WIFI devices were originally intended to communicate over the radio
waves, where the attenuation between transmitter and receiver could be
much higher. So the coax should still look like good connection that
can offer multipath-free and nearly reflection-free signal integrity.

A spare WIFI access point and a spare WIFI client box with an external
antenna connection each, a pair of attenuators and a pair of resistive
50 to 75 Ohm matching pads and some cables should be all it takes...

Are there technical reasons why this will not work (even with a pair of
attenuators to match the transmitted signal levels to the receivers) or
is the idea just too unconventional? I haven't seen it done so far.

Regards, Dimitrij

 

On Friday, 18 October 2019 23:19:53 UTC+1, Dimitrij Klingbeil wrote:

On 2019-10-14 11:04, Rob wrote:
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.

Sorry if this a little off-topic, but has anyone here tried to run WIFI
over coaxial cable in a point-to-point configuration?

Presumably, a coax not rated for 2.4 GHz will add a lot of attenuation,
but WIFI devices were originally intended to communicate over the radio
waves, where the attenuation between transmitter and receiver could be
much higher. So the coax should still look like good connection that
can offer multipath-free and nearly reflection-free signal integrity.

A spare WIFI access point and a spare WIFI client box with an external
antenna connection each, a pair of attenuators and a pair of resistive
50 to 75 Ohm matching pads and some cables should be all it takes...

Are there technical reasons why this will not work (even with a pair of
attenuators to match the transmitted signal levels to the receivers) or
is the idea just too unconventional? I haven't seen it done so far.

Regards, Dimitrij

That should work fine. Don't worry about the impedance matching as
50 and 75 ohms are near enough to make negligible difference and any
reflections in the cable will almost certainly be damped enough by
the cable loss.
Make sure you attenuate enough. The receivers will not want to see
more than about -40dBm and the transmitters could be emitting around
+25dBm.
So you should have at least 65dB attenuation in total, including cable
losses which you can probably look up or estimate from the data for
similar diameter and construction cables. Split the attenuation
roughly equally between both ends.

I have used a 15m long ultra low-loss coax (about 15mm diameter)
with an antenna at each end to re-radiate WiFi to an underground
location. It worked fine as long as the antenna at one end was a
few cm away from the base station and the device at the other end
was within a few metres of the far antenna.

John

 

[Rob]

Dimitrij Klingbeil <nospam@no-address.com> wrote:

On 2019-10-14 11:04, Rob wrote:
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.

Sorry if this a little off-topic, but has anyone here tried to run WIFI
over coaxial cable in a point-to-point configuration?

Presumably, a coax not rated for 2.4 GHz will add a lot of attenuation,
but WIFI devices were originally intended to communicate over the radio
waves, where the attenuation between transmitter and receiver could be
much higher. So the coax should still look like good connection that
can offer multipath-free and nearly reflection-free signal integrity.

A spare WIFI access point and a spare WIFI client box with an external
antenna connection each, a pair of attenuators and a pair of resistive
50 to 75 Ohm matching pads and some cables should be all it takes...

Are there technical reasons why this will not work (even with a pair of
attenuators to match the transmitted signal levels to the receivers) or
is the idea just too unconventional? I haven't seen it done so far.

Regards, Dimitrij

Yes, I used that before the MoCA thing on the coax line that we had.
It worked, but not nearly as good as the MoCA.

The WiFi used was the wellknown WRT54G and of course that was only
a 54Mbps WiFi (which, as known, at most achieves half of that rate),
so a lot slower than the MoCA which can run 100 or 400 Mbps fullduplex.

Also, as we pushed a lot of data over it we had frequent issues where
the WRT54G hung up and had to be rebooted, which never happened once
it was replaced by MoCA.

In our case the attenuation was so much that we just connected the
WiFi routers straight to the coax and the received signal level was
such (I don't remember exact values) that it was strong enough but
certainly not too strong. When your cable run is short you will need
to add an attenuator.

 

[Peter]

Rob <nomail@example.com> wrote

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.

I can report that I get 80-90 mbits/sec over 75 ohm video cable, using
the above. That's pretty good.