[RFI] Modem - Wireless - CAT 5

[Jim Brown]

--- On Tue, 12/9/08, rick darwicki <n6pe at yahoo.com> wrote:

> Running a wire pair in CAT 5 to my splitter in the shack,
> is it better to parallel all the pairs, leave them float,
> short all the unused pairs and leave them float or short
> them and connect them to one wire of the main pair? 

Hi Rick,

What signal are you splitting?  Are you talking about an actual 
Ethernet signal or a POTS line? Ethernet signals use at least two 
pairs in a CAT5 cable, and depending on the speed of the connection 
they may use all four. It is VERY important that you use them as 
pairs. 

If all you're carrying is a POTS line, you can put it on one pair of 
the cable (and you can put four lines on a CAT5). The pairs in CAT5 
cable are twisted at different rates, with the blue/blue-white pair 
having the highest twist ratio. I've recently seen some very good 
research showing that the blue/blue-white pair has significantly 
greater immunity from coupling at 60Hz than the other pairs. I 
suspect this advantage would carry up to RF, but I haven't seen data 
to support that. 

73,

Jim Brown K9YC