Brand of video balun, which cable to use ??

[tacon 0]

I need some help with the following :

im using a year old zmodo wired system , i have lost 2 video baluns, two cameras stopped to work and i assume its the cat5 cable.

are video baluns absolutely necessary one at camera end and another at the dvr ?? which brand of baluns should i buy ?

what type of cable should i use ?? cameras are like 100ft away from dvr and are installed indoors. i prefer tu use Siamese cable but not sure about it since the coax cable might no be compatible with video baluns.

it would be ok to use Security Wire Burglar Alarm 18/4 500FT Stranded Shielded Control Speaker Cable ??

[the toss 0]

A quick and simple tutorial in transmission lines. CCTC (and other systems) can be broken into 3 distinct parts. Signal source , transmission medium (cable) and signal load. Each of these parts (as part of the design) have a characteristic impedance . The characteristic impedance of the transmission medium is the theoretical impedance(NOT resistance) of a line of infinite length. When the signal source outout impedance and the signal load input impedance matches the line impedance then we obtain maximum power transfer. A bit like a irrigation system - if the pump outlet , water pipe and tap are all the same size , then you will get maximum water flow.

Now in the analogue days the impedance of everything (cctv) was 75 ohms and all was good until the new technology of IP based signal transmission came along which required UTP cable with a characteristic impedance of 100 ohm. UTP cable was dirt cheap with pretty good noise immunity and so was attractive to use for analogue systems. This required the matching of the different characteristic impedances to work. The ability to do this has been around since electronics was conceived by using a simple matching transformer. These were common to match the 300 ohm ribbon cable to your 75ohm analogue TV back in the day. So by using a balun in CCTV we match the 75 ohm camera to the 100 ohm UTP cable then back to 75 ohm at the DVR. This is why one is needed at both ends. The use of baluns does however result in a small drop in transferred signal power.

Basically baluns are baluns (given the impedance matching they are designed to do) with the more expensive ones having a bit of noise filtering built in.

So if you are planning on using 75 ohm coax cable baluns are not needed and use of them will render the system inoperable.

 

 

hope this has been helpfull

The Toss

[tacon 0]

Awesome explanation , thanks !

i live in the state of Texas , i got plans to install security cameras in the area but no alarms , do i need to get a license ??