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jonheal
2007-01-10, 13:35
Has anyone tried soldering RCA jacks on Cat-5 to make a really long (100ft) digital coax cable?

seanadams
2007-01-10, 13:42
It won't work without baluns.

Something like this would give you the right impedance match:

http://www.svideo.com/500021.html

It's hard to say how far you might be able to go... would depend on the s/pdif circuitry on either end, the quality of the cable, and the environment in which it is run.

GoCubs
2007-01-10, 13:45
Has anyone tried soldering RCA jacks on Cat-5 to make a really long (100ft) digital coax cable?

You'll need to use a balun at each end to get the signals right. I've used them before for video with amazing results.

http://www.svideo.com/500020.html

-Greg

Eric Seaberg
2007-01-10, 13:48
You'd almost be better off converting to AES and back to SPDIF. AES can go 330 meters with the proper cabling.

robertlewisca
2007-01-10, 17:01
I've used 75 ohm coax cable with an F to RCA adapter at each end. Correct impedence, works great, and is inexpensive.

TiredLegs
2007-01-10, 18:31
I have successfully used 75 ohm coax (cable TV wire) to transmit S/PDIF over a run of more than 200 feet.

However, any wire you use (coax or Cat5) cannot be carrying any other signal at the time. And if you are using Cat5, it cannot be connected to any active networking devices (no routers, hubs, etc.). None of those devices would know what to do with S/PDIF.

peter
2007-01-11, 02:25
TiredLegs wrote:
> I have successfully used 75 ohm coax (cable TV wire) to transmit S/PDIF
> over a run of more than 200 feet.
>
> However, any wire you use (coax or Cat5) cannot be carrying any other
> signal at the time. And if you are using Cat5, it cannot be connected
> to any active networking devices (no routers, hubs, etc.). None of
> those devices would know what to do with S/PDIF.
>

If you follow the link GoCubs provided you'll see the device claims to
need only one pair of CAT5 wires. So apparently you could run many over
one cat5 cable and - with a proper splitter, you should even be able to
run a 100 Mbit ethernet connection on the same line, since they use only
4 wires IIRC.

Regards,
Peter

GoCubs
2007-01-11, 07:45
TiredLegs wrote:
> I have successfully used 75 ohm coax (cable TV wire) to transmit S/PDIF
> over a run of more than 200 feet.
>
> However, any wire you use (coax or Cat5) cannot be carrying any other
> signal at the time. And if you are using Cat5, it cannot be connected
> to any active networking devices (no routers, hubs, etc.). None of
> those devices would know what to do with S/PDIF.
>

If you follow the link GoCubs provided you'll see the device claims to
need only one pair of CAT5 wires. So apparently you could run many over
one cat5 cable and - with a proper splitter, you should even be able to
run a 100 Mbit ethernet connection on the same line, since they use only
4 wires IIRC.

In my situation using the video balun I used a pair of the unused pairs on a CAT5 line I was running ethernet over (ethernet doesn't use all the pairs). I believe I separated the video pair out before it made it to my switch. I'm not sure what a switch would do. My guess would be it doesn't look at the pairs at all and likewise it wouldn't pass the signal along. A passive hub might work, but who knows...

-Greg

seanadams
2007-01-11, 09:59
I'm not sure what a switch would do.

Basically nothing. The unused pairs would typically have some ESD suppression, eg a high voltage cap to ground.

peter
2007-01-12, 09:07
seanadams wrote:
> GoCubs;169251 Wrote:
>
>> I'm not sure what a switch would do.
>>
>
> Basically nothing. The unused pairs would typically have some ESD
> suppression, eg a high voltage cap to ground.
>

Unless you would be using a gigabit capable switch like mine, they use
all 4 pairs.

I think my Audio/Video baluns use all wires too, but I could be wrong
there (they have CAT5 connectors). Perhaps I should open one up to have
a look.


Regards,
Peter