pig

Hi attached are some of the pictures as requested. I have tried a ground loop isolator on both ends of the run (not simultaneously) which solved the picture flicker, but some hum bars remain. This problem only occurs when using the CCTV power supply box. When I use a power supply plugged into a 13A socket, the picture is perfectly viewable with only a few unnoticeable hum bars. Could it be an issue with the power supply box? Regards.

Any ideas how I might overcome this?

Yes I am using passive baluns on both sides.