Hi Vitaliy:

When you have more than 1 pair in a cable the twists of each nearby pair should 
be different to reduce coupling. For example the CAT 5 cable I measured at:
http://www.prc68.com/I/Zo.shtml#Wm
has twist lengths of : 16, 17, 20 and 22 turns/foot.

If you are doing your own twisting there's a trick.  If you rotate each wire 
about it's center line in the direction opposite to the twist rotation, when 
the two wires touch each other they lock together and do not then undue the 
rotation.  If there is no rotation about the center of the wire the twisted 
pair will have random air gaps between the wires.

-- 
Have Fun,

Brooke Clarke
http://www.PRC68.com
http://www.precisionclock.com
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