Cat5 cable, Baluns and how to use them for newbies

This is just for the newcomers and those DIYer's that just want to know more.

Baluns what are they? They are transformer devices that change the impedance at both of a cable to allow a video signal to travel along it which is fast, convenient and extra economic over long runs. Okay how to use these devices and cat5 cable

Couple of things to note, he is using brick Baluns notice how tight they are when you view them at the back of a DVR.

Unless you have microscopic fingers, I suggest "Pigtail baluns" i.e. the BNC is in a pigtail wire.

Whichever pair you use to connect the baluns, I usually use the solid colour to connect to the positive terminal of the baluns at either end.

When I use Cat5 cable for various jobs I have devised my own convention as to colour coding always using the solid colour as the +ve.

Cat5 cabe is a loosely speaking is 4 pairs of unshieded twisted pairs (UTP) of 24AWG solid (or sometimes stranded) wires.

It's those twists in the pair of conductors that allow signals to travel further along the cable by reducing energy loss in magnetic fields.

Here is an info page if you are interested to find out more

There are two basic types of baluns for CCTV video, passive baluns and active baluns, there are other types but we'll leave it there for now!

Baluns don't change the impedance of the cable. They convert an UNbalanced signal into a BALunced signal (this is where the name "balun" is derived from). This can give you an impedance *match*, but it doesn't change the cable itself.

The following is a simplified explanation:

In an unbalanced signal, the signal (data) is measured as referenced to ground. The ground side of the cable tends to stay at 0 volts (because it's grounded ), so if you have a source of noise or interference it affects only the signal carrying conductor and not the ground/shield. If you have a REALLY good shield, you can prevent most sources of noise from affecting the signal carrying conductor. If you don't have a perfect shield (and you never really do), then interference can be imparted on the signal, which we see or hear as distortion and noise.

In a balanced signal there is no ground. The signal/data is measured as a delta between the two conductors. EG: in data terms a "1" might be a voltage delta of 5 volts, and a "0" might be a voltage delta of 1 volt. Because the wires are unshielded they may pick up more stray signals. However, they wires will both pick up the SAME stray signal. So the noise may impart a 3V spike on the cable, but it will be picked up up by BOTH wires. The delta between the two wires is still the same (eg: 5 volts), but instead of 0V on one wire and 5V on the other it's now 3V and 8V. The twists in a twisted pair cable ensure that the two conductors in the wire pair being used in the signal path stay in close physical proximity to each other so that they are always exposed to the same noise source at the same time.

The eHow link you posted is not completely accurate, eg: Cat5 has no limit on length of a run. *Ethernet* on a twisted pair network has a cable length limit of 100M, and this is based on timing (to detect packet collisions), not on the quality of the cable, or signal strength or anything like that.

Thank you, I stand corrected.

So Baluns with a Cat5 cable between replace the coaxial cable and you wire one balun at each end. Passive baluns are unpowered, but for even longer runs there are powered Baluns available. Quite convenient for a one time installer who doesn't possess the skill or the tool to crimp BNC

plugs.

How I have used Cat5 cable with baluns:

Use the pigtail baluns. Its just easier for tight spaces... Get them so that they fit inside you camera enclosures.

I have a color scheme:

Orange pair for positive power. (Could be 12VDC or 24VAC, etc). In case its AC, +/- doesn't matter!

Green pair for negative power. Power lines are doubled-up to handle voltage loss at longer distances.

Brown pair for Balun. Brown/white for left Balun connection, Solid Brown for right Balun connection. If you switch them up, the picture WILL look like shyte. One time I forgot and switched them, the picture was B/W with all kinds of crazy-ness!

Blue as a spare, or if the DVR won't be checked by a person for long periods of time, Blue is a tamper loop that goes to the alarm system!

Thanks for that Adam. Did you view the video clip and if so what did you think of it, not too bad was it?

As I said before, so long as you have a convention for your wiring colours, someone else coming along later on to service your work will be able to figure it out and in the case of home users, even if you forget, you will work it out bt be consistent and even use a sticky label to note your wiring colours and stick it somewhere it can be found easily.

Just one other thing, for running Cat5 outside you will need exterior grade cable. You can buy runs of Cat5 on ebay if you are only installing a few cameras in your home. The stuff is usually quite good but do read the spec to see if it's right for you. It's a more economic option than buying a 300 M box and you can choose different from colours. For short runs inside the home under 10M it's otfen cheaper to by a 10M patch lead and cut the RJ45s off or get baluns that accept RJ45 plugs. These will mostly be stranded wire and additional care may be needed. Alternatively, you can leave the RJ45s on and buy a pair of POE (power over ethernet) Balums like these below. Very convenient.

Just one other thing, Baluns are NOT waterproof so enclose your connections in a IP65 rated junction box fitted next to the camera bracket.

They cost a few pounds / dollars but t believe me when I tell you they Are necessary especially when using a pair of Baluns. It's good practice even when not using Baluns, but not always necessary. I always use one and place a sachet of silica inside to collect any slight moisture.

That was very informative, but of course I'm still confused.

What would be the difference between using a female to female BNC as opposed to a balun? I was thinking that I needed a 4 port balun in my garage (I ran a single cat5e from house to garage to run 3 cameras) but why can't I use female to female BNC's in place of the 4 port balun?

Can four of those take the place of this 4 port balun?

numb-nuts, are you CCTV42?

the reasons i have used mostly cat5 and baluns is because:

A: don't want to spend money on a crimper. although its a useful tool and i have no doubt that i'll need it one day, i want to spend as little as i have to,

B: in situations where i have 3 or 4 cameras close to each other and away from the DVR. it makes more sense to run 4 camera signals through one cable.

C: it works out cheaper than coax.

my two vantage cameras on the outside of the shed have terminals on the camera for power in and video out. it did have a BNC plug connected to the video out on both cameras but i only had two baluns left and i wanted to get the cameras up. i decided to take the bnc lead off and connect the video cores of my cat5 cable straight to the camera. i accepted there would be noise but it was only going to be temporary until i got some more baluns.

got to the DVR end, attached the two baluns i had to the cores the cameras were connected to and i was amazed at the picture quality!

the new baluns arrived and i went and put one in one of the cameras but did not notice a difference in image at the dvr (iknow, the quality was really good!) so i just left the other one with the video cores going straight into the camera. works fine.

can i use CAT5 for PTZs? i want to use 4 cores for power, 2 for video and 2 for RS-232. my ptz cameras can be controlled via the coax video line but they are going to be on my chimney and if i replace my DVR i'd rather not have to go up there and mess about with changing cores around.

That was very informative, but of course I'm still confused.

You wouldn't be if you read the first two posts of the thread.

What would be the difference between using a female to female BNC as opposed to a balun?

All the female-to-female connector (often called "lesbian adapters") does is allow you to join two male BNC connectors together. It doesn't balance or unbalance the signal as described in Brian's post, and it doesn't give you an easy way to connect twisted pair wires.

Can four of those take the place of this 4 port balun?

No - they have entirely different functions.

can i use CAT5 for PTZs? i want to use 4 cores for power, 2 for video and 2 for RS-232. my ptz cameras can be controlled via the coax video line but they are going to be on my chimney and if i replace my DVR i'd rather not have to go up there and mess about with changing cores around.

You can do that, but two 24ga. pairs may not be enough to handle the current requirements of a PTZ. You need to look up the PTZ's power or amperage ratings, then plug that and the wire length into a voltage-loss calculator, like this one: http://www.netkrom.com/voltage_loss_over_cat5_calculator.html

One other thing to note: Baluns DO NOT require UTP (unshielded twisted pair) cable. Cat5e is used most often, because it's commonly available, relatively low cost, provides flexibility by allowing power, video and control OR multiple video signals on one wire, and provides for future upgrading to network cameras... however, baluns will work just as well over lower-grade UTP (like Cat3 cable), large multicore cables (like old 25-pair telephone cables), or even non-twisted cable like speaker wire, microphone wire, station wire, etc.

thanks for that. i have bookmarked that calculator. it will be very useful

numb-nuts, are you CCTV42?

No, I just think the videos are very helpful. CCTV42 is run by the chap in the videos a chap called Henry. A very nice guy I met at IFSEC

I would also echo what Adam said, I like to use pigtail baluns becuse they fre easier to install when space is tight like at the back of a DVR.

numb-nuts, are you CCTV42?

 

No, I just think the videos are very helpful. CCTV42 is run by the chap in the videos a chap called Henry. A very nice guy I met at IFSEC

ahh. i like henry, he has a voice that would be good for children's TV. i was going to tell him in a comment but thought he may be offended so i didn't

You mean instead of CCTV he should be in CBBC ?

You mean instead of CCTV he should be in CBBC ?

yup

Talk nice to mr tumble Henry and he might give you a porsche

★★★★★ This PDF is very good in explaining the use of Cat 5 cable and Baluns. ★★★★★

http://www.systemq.com/PDG_Commerce/TeleSales/pdfs/tips/TechnicalTip-0067.pdf

Thread revival time.

Baluns are easy to use etc etc. But really causes a mess of wires at the back of the DVR.

How do you guys neaten it up?