[Lowfer] Cat 5 cable

Thu, 01 May 2003 23:23:22 -0400

Bill

BTW...are you transmitting tonight? I'm seeing absolutely nothing on dot 3.

Jay

Jay Rusgrove wrote:

> 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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