[na-user] Monitor Noise

[David A. Pruett]

The old monochrome TTL, CGA and VGA monitors had digital interfaces.  VGA
and later generally have analog interfaces.  From the electrical
engineering point of view, RF noise on monitor interfaces is related to the
rise time of the waveform.  Digital signals tend to have very fast rise
times, analog interfaces can usually tolerate some slope which helps for
noise.

The old color CGAs were pretty bad for noise.  I had good luck noise-wise
with the one EGA monitor I had.  The worst setup I ever had for noise was a
special Paradise card which did grey scale on a TTL monochrome monitor (it
pulse-width-modulated the signal).

Five of the six monitors at K8CC are cheap VGAs and we rarely have any
noise problems anymore.  However, the wobbly image from a nearby
transformer that W8KX mentions is a big problem.  Ham-M rotator boxes cause
the same effect.  I am looking lustfully at the new breed of color LCD
monitors which would make this problem go away.  Yeah, these are expensive,
but what worries me more is not knowing how these work in DOS text mode. 
Everything these days is GUI, where any resolution or dot count can be
handled.  Not so with a fixed number of characters.

73,

K8CC


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