"Paul" schreef in bericht
...
Linea Recta wrote:
Today I bought a VGA cable for someone. Back at home I noticed the
following text on the blister: "designed to work with monitors smaller
than 17 inches". No idea what this is about. It is to be used with a 21.6
monitor.

Anyone ever heard of cables specially for certain monitor sizes??

This is some kind of half-assed admission that the coaxial
cables for RGB in the VGA cable, have a relatively high loss.

For any VGA cable, if you make it long enough, it gets
fuzzy above 1024x768 approximately. So if you run a 50 foot
or 100 foot cable somewhere, you would not expect to use
1600x1200 as a screen resolution choice, and view a good
quality image. Dropping to 1024x768, makes the lack of
sharpness less apparent.

Coax cables can be made in a range of qualities. So 50ft of
cable made from one flavor of internal coax, could be inferior
to another.

If the cable is relatively short, it really shouldn't
have an issue with this stuff. Bandwidth limitations
should be more apparent on long runs. If this is a
six foot cable between computer and monitor, it would
have to be almost "non-coaxial" to be that bad.
Note that, of the five signals RGBHV, many cables
carry H and V as twisted pairs or separate wire next
to a ground, while only RGB have the higher quality
coax used. In the following example, they use coax for
all five.

My old Sony Trinitron, came with a five coax cable and
individual BNC connectors. The cable has VGA on one
end, and separate coax span from the VGA to the monitor
itself. This causes the monitor to not support EDID
(the computer can't tell what resolutions it supports),
but the usage of separate coax, would allow longer cable
runs. So it is possible to make longer runs of cable,
or even fabricate your own - if the monitor, like my
Trinitron, had five BNC connectors on the back as
the input. So if I wanted to run a VGA signal the
absolutely longest distance without regeneration,
I might look into this approach. Since you can buy
VGA connectors with just pins on the back, you can
build your own cables if you want ("home coax" and all).

http://site.ambery.com/webgraph/VGA-5BNC-Cable.gif

You can certainly try the cable with your 21" monitor.
If the picture is too fuzzy, then you'll have your
answer. Run the monitor at native resolution, to
give the results a fair evaluation. Don't run it
at 1024x768 and "call it good". The native resolution
is the resolution where there is no scaling between
the incoming signal and the pixels on the screen,
so "one pixel coming in, gives one pixel going out".

And doing an "A-B" comparison, compare two VGA
cables, may give you some idea how much this
cheap cable is screwing up the quality.

Paul



Thanks for your comprehensive reply. Where do you get that much time? :-)
This cable wasn't especially cheap, at least that's not what I call 10,50
Euro.
The cable length is 1.8 meter, so not very long. Belkin F2N028cp

Going to connect it friday, Asus VW220TE to an old (only VGA) computer. I
expect it to be sufficient.



--
regards,

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