ScrewType BNC Vs CrimpType BNC - Solved

I am trying to set a CCTV system and collecting the required hardware. The one thing that still is a bit confusing is the way the link video cable is connected to the camera. The camera has a BNC male and my link cable is a two core power + RG59 coax.

I have some options with regard to the way the Coax cable is connected to the BNC. The easiest is the screw type BNC...

ScrewType BNC.JPG

And the other is the Crimp type BNC.

CrimpType BNC.JPG

Just wanted to know if the screw type BNC is any good and if it will degrade the quality of the video signal ? Its a 5MP camera with AHD video out.

Thanks for any suggestions.

CrimpType BNC.JPG

ScrewType BNC.JPG

By far the best is to use the Crimp type, it was designed for Coax the other was not.
This response is to help you get started in solving your problem, not solve it for you.
Good Luck & Have Fun!
Gil

The screw type connectors definitely will degrade the signal more than the real connectors; whether the amount of degradation will be acceptable, I do not know, but am not particularly optimistic given that you want to send analog HD over it.

The screw type connectors also are generally kind of crappy - it's easy to yank the wires out, short them out, etc - I suspect the level of degradation would vary noticeably depending on how carefully you screwed, stripped, and cut the wire.

They also make you look like an amateur. You may not care, and I have things that look awful wired up and working, but if you like showing your friends your electronics, you may.

DrAzzy:
The screw type connectors definitely will degrade the signal more than the real connectors; whether the amount of degradation will be acceptable, I do not know, but am not particularly optimistic given that you want to send analog HD over it.

The screw type connectors also are generally kind of crappy - it's easy to yank the wires out, short them out, etc - I suspect the level of degradation would vary noticeably depending on how carefully you screwed, stripped, and cut the wire.

They also make you look like an amateur. You may not care, and I have things that look awful wired up and working, but if you like showing your friends your electronics, you may.

Guessed as much. No no for sure I am quite serious about a good installation and not just to show i can get a CCTV image to show up !! ( That phase is already over :wink:

Maybe i will settle down for a BNC connector which has a screw to tighten the signal wire and have the shield crimped ... its easy rather than the full compression type as that needs a tool !!

Thanks

I am surprised you do not simply use a pre-manufactured cable. :roll_eyes:

Video uses 75 ohm throughout, beware of this as some BNC connectors are 50 ohm and others are 75 ohm,
You must use 75.

Paul__B:
I am surprised you do not simply use a pre-manufactured cable. :roll_eyes:

Because they don't make them every length for a CCTV install of course!!

You can get BNC compression connectors for RG-59, similar to the common type-F compression connectors used for cable/CATV wiring, if you have access to the tool to install them.

MarkT:
Video uses 75 ohm throughout, beware of this as some BNC connectors are 50 ohm and others are 75 ohm,
You must use 75.

Thanks... that 75 Ohm was the fine print that many CCTV data sheets do not mention. It is just RG59 BNC. Possibly that means 75 Ohm.

Thanks to all those who responded... I will go ahead with the crimp type 75 Ohm BNC.

And just for info. if there any white paper that talks about the quantitave signal degradation when using different methods to extend RG59 cables starting with the quick and dirty Splicing to the ultimate Crimped BNC ?

Mogaraghu:
Thanks... that 75 Ohm was the fine print that many CCTV data sheets do not mention. It is just RG59 BNC. Possibly that means 75 Ohm.

Video (which is baseband) is always and always has been 75 ohm. RF stuff is usually 50 ohm (and usually narrowband) Everyone in the industry knows this. RG59 is 75 ohm, easy to look this up.

BNCs are the only connector I can think of that comes in both 50 ohm and 75 ohm forms, and they are not compatible, electrically or physically (you can force one into the other, this can distort the centre pin connection though).

And just for info. if there any white paper that talks about the quantitave signal degradation when using different methods to extend RG59 cables starting with the quick and dirty Splicing to the ultimate Crimped BNC ?

Depends on the max frequencies involved. Video is more demanding in that phase and amplitude variations with frequency make visible artifacts on vertical edges, and reflections cause ghosting. For RF narrow band all you usually care about is loss at one frequency and at high power the VSWR.

75 ohm was long ago chosen as lowest loss point for coax, and 30 ohm as highest power handling, and 50 ohm is a compromise value. 30 ohm flexible cable is difficult to manufacture so 50 and 75 ohm predominated.

MarkT:
BNCs are the only connector I can think of that comes in both 50 ohm and 75 ohm forms, and they are not compatible, electrically or physically (you can force one into the other, this can distort the centre pin connection though).

The pin on the 50 Ohm is larger.

Thanks to all those who helped out. And in particular to MarkT who ran a short tutorial on the topic. Appreciate that !