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What are causes of line loss on an extension?

DrSeeAll
Grafter
Posts: 51
Registered: 30-07-2007

What are causes of line loss on an extension?

My S/N figure is about 16dB.
I've just installed a hardwired exension to the far end of the house using normal 4 core telephone wire.(~30m long) and the S/N figure has dropped to 6dB - no phone or filter connected. Not good enough to maintain good BB connection

The resistance in each wire is about 4 Ohm. I had to make some joins in the wires but they where all soldered and taped.

How can I improve the situation or is it simply the length of the run that is causing the loss? Would a heavy duty cable with no joins make a significant difference?

TIA
4 REPLIES
Community Veteran
Posts: 4,729
Registered: 04-04-2007

What are causes of line loss on an extension?

Problems can be caused by the stray capacitance of the cable, and pickup of external electrical noise, ie running the cable next to mains electrical cables.

A couple of suggestions;

1) Try running the extension cable using cat5e or cat6 network cable and away from any mains wiring within the house. (300mm separation should be sufficient, where practical) And also make sure that the cable does not loop any mains cabling. Also joints should be avoided.
2) If possible I would sit the router (if you are using a router rather than a USB modem.) at the phone point and run the extension as Ethernet.

Chilly
DrSeeAll
Grafter
Posts: 51
Registered: 30-07-2007

What are causes of line loss on an extension?

Hi
Thanks for your answer. The extension I've installed is purely for an additional telephone.
The wireless router is located on a short extension from the main socket and worked OK until I put in the new telephone wiring.

Are you suggesting that I use cat5/6 cable simply for the telephone as it is better quality than 4 core telephone cable? Or have you misunderstood and thought I wanted a long ethernet connection?

The bulk of the telephone extension is outside the house (no joins outside though).

Thanks again
Community Veteran
Posts: 4,729
Registered: 04-04-2007

What are causes of line loss on an extension?

Sorry I did misunderstand that the router was at the end of the extension cable.

Option 3)
If practical fit one of the original BT face plate ADSL splitters, this will separate the ADSL / Telephone at the master socket where they enter your house.

See this link
http://portal.plus.net/central/forums/viewtopic.php?t=9996

Chilly
DrSeeAll
Grafter
Posts: 51
Registered: 30-07-2007

What are causes of line loss on an extension?

The problem with this is the wireless modem/router has to be located (upstairs) away from the master socket to give good wireless coverage.

What do you think is the problem with the new telephone extension? Is it just the length (~30m) or would I benefit from re-doing it with thicker wire (less resistance) although I would not have thought that 4 Ohm was a problem?