I've replaced all my old analogue cctv cameras with ip cameras and pulled cat6 cables through to replace the existing coax and power cables but there's one that's impossible to replace. I need to run one camera through coax and have tried using a pair of coax to cat6 balun but it doesn't work. I've tried 3 different sets but none of them work. The power lights on the back of the NVR don't come on at all. I've tried putting 12 vdc directly to the camera while it's connected through the balun but that doesn't work either. Does anyone have any further advice please? Thanks