dannyharding

Hi all, Hope someone can help me I've recently just installed a Swann 4-4575 DVR with 2 HD PRO-T853 Cameras, and for ease I have put in 2 Cat5e cables in (1 for each camera) the furthest run is about 30m more or less, and using quite cheap baluns from ebay at either end. When I connect the 1st camera the picture is okay not perfect is a little bit hazy but no visible interference. As soon as I power up the second camera, interference shows up on the 1st camera. If i connect the second camera by itself it still is a terrible picture with horizontal lines scrolling down the screen. Things I have tried: 1. 3 separate plug PSU's for each camera and DVR (same problem). 2. fitting a isolator on the second camera. (makes no difference). I've done a bit of googling and seen you can buy "HD Baluns" but do they really make a massive difference over 30m? Also just mocked up a test camera using 300m drum of cat5e using these baluns but camera is not HD and baluns held up fine, so I'm really confused. Cant say I've tried putting a non-HD camera on the set up yet to see if it makes any difference. If anyone else has any ideas what it might be would be very grateful.