Can I passively (no electricity) move a phone line to a different room via coax

brimur69

Hi guys,

I have a home office with a networking rack and UPS. Other than APs everything is in that rack except the vDSL modem which is in the living room because that is where the phone line comes into the house. The office is upstairs on the other side of the house. The power goes often enough that I needed a UPS to keep working and sometimes for an hour or more. The office UPS can keep my desk and network on for hours but the internet goes because the modem is in the living room and not on UPS. I took the UPS downstairs one time when the power was out for a few hours and put the modem on it and the internet worked so I wanted to move the modem upstairs onto the UPS if possible

There is a TV aerial socket (RCA) next to the phone line which I am currently using with two MOCA devices to connect to my office and cabinet upstairs. The two rooms are connected directly from a coax point of view, as in not split to other rooms, and the signal is perfect. Rather than buy another UPS to keep the modem going for hours is it possible to move the vDSL modem up to my cabinet and extend the rj11 phone line passively over the RCA cable to upstairs.

Some of the things I was looking at were these...

RJ45 to COAX

https://www.amazon.co.uk/Metronic-Ethernet-Coaxial-Metres-395285-dp-B0BN5WGYFD/dp/B0BN5WGYFD

https://www.amazon.co.uk/dp/B08N4JHGTR

RJ45 to RJ11

https://www.amazon.co.uk/SHONCO-Ethernet-Splitter-Network-Extender/dp/B0967SK49C

My thought process was to use the RJ11 adapter with one of the passive cables and then the reverse up in the office. No electricity needed but I dont know if the signal would be lost along the way so wanted to check before wasting money on it.

Thanks

Glaceon

You could have an impedance mismatch between the telephone cable and coax (100 ohm vs 75 ohm I think). That could be a problem for something as sensitive as VDSL. It would probably work but I'd say your line speed would reduce.

brimur69

https://www.boards.ie/discussion/comment/120975876#Comment_120975876

Thanks, I currently only get ~20Mbps anyway on a 100Mb package so that might be a problem alright if it went any lower. 😔

Tow

Standard phone line is 600 ohms. Cat 5/6 which is used internally in modern buildings is 100 ohms. in It will probably work fine with 75 Ohm TV coax. Keep in mind that there is 50volts on the phone line when it rings.

brimur69

https://www.boards.ie/discussion/comment/120975924#Comment_120975924

Thanks. Will the voltage matter if its passively going over different mediums but still ending up at the vDSL modem?

Tow

https://www.boards.ie/discussion/comment/120976102#Comment_120976102

Not if it is passive, you don't want any baluns or filters before the Modem.

10-10-20

Would an mini-UPS do what you need as extending the cable is never a good idea with telephony based systems?

https://www.eaton.com/ie/en-gb/catalog/backup-power-ups-surge-it-power-distribution/eaton-3s-mini-ups---emea.html

9v, 12v 15v and 19v. Hunt Office have them available.

GerardKeating

Saw a YouTube video on the "goCoax MoCA 2.5 Adapter with 2.5GbE Ethernet Port". They seem to give gigabit performance on normal TV coax cable.

I did consider it, but two 40m CAT-8 cable in the attic with the cable dripping down the walls won out.

brimur69

https://www.boards.ie/discussion/comment/120976171#Comment_120976171

Thanks. This is unrelated to my question as my issue is getting a modem upstairs but I do actually have those at the moment and did see 2.5Gbps speeds from them when I tested them.

brimur69

https://www.boards.ie/discussion/comment/120976167#Comment_120976167

I will go this way eventually I suppose if moving the modem upstairs fails

niallb

I'd say go for it and see what happens.

Your biggest issue might be getting a network signal back down to the TV as I think your MOCA network might collapse if you run the analog phone signal over the same cable. Getting a call in on the line could blow them completely and they're not cheap!

You can put back what you have very easily if your speed drops, but I'd say it's one or the other.