Using CAT6 Cables for Analog HD Cameras is not mostly recommended.If you are using CAT 6 Cables for HD CCTV Cameras , Please ensure below things for proper working of cctv cameras.
Balun Connector – Video Balun / UTP Balun
While opting for CAT6 Cable over traditional coaxial cable , Video baluns are must. Video Baluns helps in uninterrupted signal transmission over cat6 cables.
Separate power adapters for each cctv cameras is a must while using cat6 cables. Either you can put it at camera end or at dvr side cable end. Using Single SMPS would create lots of problems with cctv camera if CAT6 Cables are used.