In article ,
glen herrmannsfeldt wrote:

JohnO wrote:

"philo" wrote in message
(snip)

VGA cable is shielded
and CAT5 is not, so you would get some horrible ghosting.

BTW, there may still be some ghosting even with VGA cable

STP CAT5e or CAT 6 would do the trick, and at these
lengths the cost difference isn't an issue.

There might be a minimum amount that they will sell, but the
real problem isn't shielding but impedance and
balanced/unbalanced line.

If you transition from a balanced line (UTP) to an unbalanced
line (coax), unless exactly impedance matched, it won't
work right. UTP cable depends on the voltage and currents
on the two wires being exactly opposite to cancel out and
not radiate the signal. Coax depends on the voltage on the
shield being zero. To couple between them you either need
a transformer (if there is no DC component), or active
circuitry such as differential amplifiers. VGA has a
DC component so you can't use transformers.

-- glen

You can use a transformer, but wired as a *balun* (coils in series with
the lines instead of across them); this provides the required impedance
transformation while still passing DC.


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