[Lowfer] Cat 5 cable

[Jay Rusgrove]

Bill

There is some info on twisted pairs in the ARRL Handbook editions around 1980 or
1981 - may still be in current editions - we made quite a few measurements in
the lab around that time on enameled copper wire twisted pairs for use on
ferrite cores as baluns. Conductor size, separation and number of twists per
inch control control the line impedance. A pair of  #24 enameled wires at 3.5
twists per inch has an impedance of about 50 ohms. CAT 5 which is #24 with 3.5
twists per inch with the added insulation thickness (and conductor separation)
is about 100 ohms.

The twisting together of numerous pairs is a whole science unto itself. Paul or
one of his Telco guys will have to fill us in on that!

Jay

Bill Ashlock wrote:

> Paul,
>
> Thanks for the chart on cat 5 cable losses. I've used this stuff many times
> in the past for home computer networking and even worked for a while for one
> of the local schools insalling a network but confess I know next to nothing
> about the theory of how it works as a transmission line - and it sure
> appears to be designed contrary to my undestanding of how a transmission
> line should work. It must work pretty darn well because local networking
> hardware doesn't support coax any more. The "experts" I talked to, back
> then, didn't have a clue of how it works. Do you know of any web sites that
> cover these details?
>
> Thanks.
>
> Bill
>
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