To make a custom video extension cable for a Macintosh II, you'll need a
cable with a 75-ohm impudence value (usually RG59U standard coaxial video
cable). Each line can be tied to the appropriate pin at the connector and
the shield connected to the signal ground pin.
- Impedance: 75 ohm
- signal strength: 13.33 amps, 1 volt
The video signal can extend as far as 1,000 feet (though there is some
color loss at this distance). The signal should be reliable up to 50 feet.
The distance is limited by the loss of signal strength through cable
resistance.
For more information on pinouts and cabling, search under "Macintosh II
video signals".