Topband: twisted pair cable

[Jim Brown]

On 9/8/2013 11:48 AM, Bruce wrote:
> Of the cables this company is selling it appears the only one that has 
> its impedance (55 ohms) posted.

The Zo of most paired cable is in the range of 60-80 ohms. You've got to 
work at it to get the Zo much higher. CAT5/6/7 is speced at 100 ohms, 
but with a tolerance on the order of 20%. :)

> I decided to cut a section lengthwise to find out if the drain wire 
> was in fact was next to the twisted pair and it is not. It runs in a 
> straight line on the outside of the foil. 

That's very interesting, because it means the cable industry is finally 
starting to pay attention to the research Neil Muncy published in 1994. 
:)  Several years ago, Gepco introduced "rack wire" with a shield that 
is foil plus a light braid, which is an even better solution.

73, Jim K9YC