Long vga cable with STP

Written by Walter on x/x/2004

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Need this for my dad. He wants to install a long vga cable for a HTPC (longer than 15meters). First I thought it would be very expensive (since my 13meter vga cable cost a lot already). But furtunately thanks to hackaday, we can now just use a STP (cat 5 shielded twisted pair, so similar to UTP...) cable which is a lot cheaper.

The only local place I could find shielded Cat 5 products was at Fry's. L-com has them but they are mail order and a little more expensive.

I did the exact same thing as before. I bought a 25 foot shielded cat 5 cable and cut it into a 6 foot and 19 foot piece. I also bought a shielded Cat 5 junction box, two HD-15 male solder cup plugs and to 9-pin metal hoods (HD-15 is the same size). I wired the HD-15's in the following fashion to the shielded cat 5 cable.

HD-15 pin Cat 5 color
1. Red + Orange
2. Green + Green
3. Blue + Blue
6. Red - (aka GND) Orange stripe
7. Green - (GND) Green stripe
8. Blue - (GND) Blue stripe
10. Ground (GND) shield wire.
13. H sync Brown
14. V sync Brown stripe

Extended table:

VGA Video connector pinouts:
Pin # - Signal Name - CAT 5 Conductor
1  -   Red     -  Orange     
2  -   Green  -  Green
3  -   Blue    -  Blue
4  -   No Connection
5  -   Ground - No Connection
6  -   Ground - Orange/White
7  -   Ground - Green/White
8  -   Ground - Blue/White
9  -   No Connection
10 -  Ground - No Connection -
11 -  No Connect
12 -  DDC DAT - No Connection
13 -  Horizontal Synchronization - Brown
14 -  Vertical Synchronization  - Brown White
15 -  DDC Clock - No Connection

The "-" signals are actually the very same ground as "Ground" is. The H and V don't need their own separate ground line. The results were excellent as I stated before.

At this point you might be saying cool but what does shielded Cat 5 give me over bundled coax? It gives a few things:

  1. Thinner form factor.
  2. Cheaper cable. Plenum being much cheaper
  3. Much easier to solder to an HD-15 connector. Bundled coax requires shield terminators when soldering and big mouth back shells to allow the larger diameter of the cable to exit.
  4. similarly, no break-out BNC to HD-15 cables required. These bring their own problems
References :

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