[ot] use of a long coaxial cable

[David Bandel]

On 1/21/07, Ric Moore <wayward4now at gmail.com> wrote:
> On Sat, 2007-01-20 at 20:38 +0800, Man-wai CHANG wrote:
> > > 10base2 is 50 Ohm.. period.
> > > 75 Ohm is probably (cable) TV or radio.
> >
> > Do we need special equipment to measure impedance? I have forgotten my
> > A-Level physics... :)
>
> Just an Ohm meter...
>
> E = I times R
> Energy = Impedence times Resistance  which translates to:
> Volts = Amperage times Ohms.
>
> I've always wondered why they changed all the words?? Who and When?
>

They may have changed some of the words at some point, but resistance
and impedance are not the same.  Resistance is static.  Impedance,
however, is not static, it changes depending on frequency.  You don't
just measure impedance with an ohm meter.  Consider yourself gonged.
Show's over for you.  Please leave the planet.  Resistance is futile.

The coax jacket should be marked with a number of things including its
manufacturer, category, impedance, frequency, and number of feet from
the end of the roll.  Those markings may still be present somewhere
along its length.  After all, the markings are made every two feet.

Ciao,

David A. Bandel
-- 
Focus on the dream, not the competition.
            - Nemesis Air Racing Team motto