Fitting BNC plugs

[Scoby_Beasley]

Recently had a look at my locals cctv system, but it's something outside my area of expertise, so tbh, was sort of fiddling in the wind.

Anyway, t'other day one of the broken cameras started again. So re-looking at the back of the video/dvd machine a few of the plugs look a bit battle worn.

We decided the next plan of action is to put new connectors on the cables.
1.) I take it that I'm right in calling them BNC plugs?
2.) Which are the best. Crimp or (I think I've seen) screw-on?
3.) What's the difference between RG58, RG59 etc.? Is that down to size?

 

[scott1980]

Poorly made off BNC connectors is quite a common cause of video loss faults.

This is a BNC connector:

View media item 59315
There are crimp, twist and solder BNC connectors. If done correctly, I prefer crimp on over the other two. Twist on are OK for the odd temporary connection or in a pickle. Never used the solder type.

RG58 has a slightly smaller outer diameter and lower impedance compared to RG59. Most CCTV installs using coaxial cable will be using RG59.

If you're going to use crimp on BNCs, you'll need a special crimping tool and the three part BNC crimps shown above. I'd also recommend you get a three way stripping tool if you've never done them before. You can strip RG59 with side cutters or a knife, but it's important to cut the various layers of the cable to the correct length. The stripping tool will ensure you have a nice, cleanly cut cable ready for crimping.

 

[bernardgreen]

The charactoristic impedance of RG58 is 50 ohm and that of RG59 is 75 ohm.

The charactistic impedance must match the impedance of the equipment being connected.

The use of cable with the wrong charactoristic impedance means signals can be reduced in strength and / or distorted by signal reflections at the points where the charactoristic impedances are not matched.

 

[Scoby_Beasley]

Thanks for the hints and tips lads!