🚀 go-pugleaf

Yes, length makes a difference.  WHEN the rise time of the signal is
included.  

For example a very slowly changing signal doesn't care whether you used 50
ohm, 75 ohm, or even romex.  

The rise times of ethernet are slow enough that a 2 inch, or 2 foot
mismatch doesn't matter much.  

You may not know this but almost all tees used in 75 ohm systems are
actually 50 ohm tees.  They're so short and most video is too slow to care
about that miniscule mismatch.

                                    - Robert -


On 30 Aug 1998, Smith and O'Halloran wrote:

> In article <35e6319c.53011606@news.lakwod1.co.home.com>,
> Aaron Blosser <blosser@home.com> wrote:
> >On Fri, 21 Aug 1998 11:07:04 -0500, Daniel Erskine
> >For short runs of cable, I highly doubt that using 50ohm vs. 75ohm would
> >make a difference.  That measurement is a measure of the cable's
> >impedance over some distance (1000 ft?), so for a short bit of maybe
> >50-100 ft, the difference *may* be neglible.
> 
> Oh, it does make a difference.  Even a two-inch length of the wrong
> cable causes reflections.  The characteristic impedance of a cable
> is the same as value of the resistor that can terminate the cable without
> causing reflections or anti-reflections; it has nothing to due
> with the length of the cable.
> 	-Joe
> -- 
> INWAP.COM is Joe and Sally Smith, John and Chris O'Halloran and our cats
> See http://www.inwap.com/ for "ReBoot", PDP-10, and Clan MacLeod.
> 
>