15 Aug
2014
15 Aug
'14
6:10 p.m.
On Aug 15, 2014, at 5:25 PM, Tony Duell <ard at p850ug1.demon.co.uk> wrote:
I don't
know about Mac monitor cables but AUI cables are not strictly straight
through. If I recall correctly, AUI cables are supposed to consist of four
individually screened pairs. The remaining 3 pins may or may not be connected.
It is 4 pairs, but I don't rememebr them being individually screened (and
I have made AUI cables). 3 signal pairs (transmit, receive, collision)
and a power pair. The powerpair is thicker wire than the other 3. From the Ethernet 2 spec:
7.2.2 Transceiver Cable Parameters
7.2.2.1 Mechanical Configuration
The transceiver cable consists of four stranded, shielded twisted pair conductors, plus an
overall shield and insulating jacket. The conductor and jacket insulating material may be
polyethylene or other suitable material. The flammability characteristics of the
insulating material must be suitable for the installed environment.
...
7.2.2.6 Resistance
The resistance of the conductors used for the power pair shall not exceed 40 mOhm/meter.
For a 50 meter transceiver cable, this implies that the distribution impedance of the
power supplied to the transceiver shall not exceed 4 Ohm
paul