VGA cable

ARWadsworth wrote on 31/08/2011 :

You cannot just use an unlimited length of VGA cable. I think 3m is the maximum. I think they are wire in twisted pairs (like LAN cable), one signal the other ground return.

VGA to RF, might be better for a distance run, or 1v p to p BNC, or SCART.

You can put VGA over cat5 up to about 120m.

I've used 20-30m runs happily. VGA (using decent (separately screened RGB lines) cable) is less prone to noise than composite over such distances.

I've used 10 metre VGA extension cable without any issues. Maplin sell

Mr Bloomfield's reply seems not to have arrived here, but I've seen a

There was a time that VGA cables of a reasonable quality were frightening prices. It looks rather like Maplin have not noticed that time has passed!

dennis@home wrote on 31/08/2011 :

With a pair of baluns !

OK, OK - my knowledge seems to out of date on this one. In early days of VGA, it was impossible to get long leads or extensions, because the suggestion was that it degraded so quickly.

I wouldn't use baluns.

It really depends on what resolution you want, plain VGA (640x480) is quite easy to put down 20-30m cables. Higher resolutions don't like it much.

If you go into a data centre you will find lots of VGA outputs are connected to kvm switches using cat5, along with the mice and keyboards. there aren't enough pairs in cat5 to just use baluns and only one cable. Some even use IP and network switches.

VGA is not designed to cover long distances an IME it doesn't.

But not as VGA though.

I'd install cat5 and use a cat5 VGA extender.

The longest off the shelf VGA lead I can find is this one

Cat5, probably a few of them

You can run VGA over longer cables than the spec says, if you're lucky. This depends on the resolution you're using (VGA is 640x480, and you're probably runnign a lot more than this) and on the behaviour of the monitor you're driving. LCD tends to work better without degradation than CRT, until it gets to a point when it suddenly stops altogether. There are also tricks for playing with the termination capacitors in the cable connectors.

Really though, this is a mug's game. Baluns are available to run VGA (and higher) over Cat5. They just work. Try CPC.

I think the image quality at 75m would be disappointing over any cable.

From experience, 30-50m is a sensible limit for the basic VGA interface, beyond that the separate syncs loose integrity and you need to use HF precompensation to keep the video edges but I've had success running to

As already suggested, for a CCTV signal either modulators or baluns over cat5e sound the most sensible and cost effective option. I'm having my doubts about VGA over the 15m or so I have here, and I actually have the cable on the shelf.

Well it does on a basic lead - and to be fair, some time ago that is all you could find easily - even a short one or two metre extension could cause a big signal mess. The higher the resolution and refresh rate, the worse it got.

With decent lead that uses mini co-ax for the actual video signals, the situation is much better. Even fairly high rates and resolutions can be carried a reasonable distance without too much degradation.

In article , Harry Bloomfield scribeth thus

You should find CAT 5 with BALUNS thereon is OK for around 100 feet and more .. just that the High frequency definition rolls off with distance as does the contrast on the pic but that can be compensated for...

Andy Dingley :

I've been using them for years and IME they don't "just work". They work for a while but every so often the receiver loses the signal and blanks out. The signal comes back a seconds or two later but it's still annoying. This happens on two different cable runs, and I've used a variety of PCs at the transmitter end, a variety of monitors at the receiver end, and a variety of active and passive adapters, and the problem's still there. It's most annoying.

En el artículo , Andy Burns escribió:

I've used 30m, and the picture was acceptable, if not wonderful. A lot will depend on the quality of the cable.

En el artículo , Harry Bloomfield escribió:

No, three individually screened micro-coax for RGB and signal wires. In good quality cables anyway.