Quote:
...using shielded Cat5 networking cable... |
CAT5 STP is a 100 ohm, 50 pf/ft balanced cable. It is not designed for 75 ohm single ended applications.
CAT5 into a 75 ohm connector will reflect 25% of the signal back into the cable, due to the mismatch, which will result in ringing and all kinds of distortion.
CAT5 is designed for balanced application where common mode rejection mostly nullifies crosstalk between pairs, and reduces shielding requirements. Typically, single ended applications would not find CAT5 to be shielded well enough and will have cross talk problems.
CAT5 with the appropriate circuitry to provide loss-less conversion from single ended to balanced mode, and impedance matching, might yield fairly decent long distance transmission capabilities with video.... and with that goes an increase in cost and complexity.
For a quality signal, stick with a properly matched (75 ohm), low capacitance, single-ended coax cable. You don't have to pay an arm and a leg; cable engineered specifically for video applications isn't that expensive. Gepco sells direct to the public, and
does sell by the foot. From a recent quote:
RGB250 $ .83/FT.
VS32001 $1.48/FT.
RGBSC260TS $1.39/FT.
Belden, Mohawk-cdt, and many other have similar offerings, but, you usually have to buy in bulk and you usually have to go through distribution.
I am sorry, I'm an electrical engineer, and hearing talk of CAT5 for video applications raises the hair on the back of my neck about the same way as dragging finger nails across a black board... I don't mean to over react.
-Ted-