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Thank you for your comments guys. Martin

With respect I was taking notice of all replies so far. It's just that everyone just says "it won't work" without explaining why. I have already done tests simulating low voltage at the turbo HD cameras and they simply just do not behave in the way mentioned in my original post. Sorry to sound anal but I was really hoping someone could say something like "oh yes I've seen that behaviour before and it's due to crosstalk" or something like that. Thanks for your patience. Martin

Thanks Securame, but can you explain why? Notwithstanding the above discussions...

Sorry Tom, perhaps I didn't explain things very well. The 24v power supply is capable of 5A total max output. However, the actual current drawn down the Cat5 pair is only around 700mA...

Sorry, I should have said it is a 5A 24v supply and I think it is 24 gauge Cat5. Anyway, I measured 15 ohms round trip resistance over the 80 meters distance...

I have worked out that the current draw on the 24v side is around 700mA, so with approx 15 ohms drop over the feed and return legs of the Cat5 gives a volt drop of 10.5v which I admit is very close to the regulator's limit to provide 12v output. Nevertheless, I have done some tests where I have lowered the supply voltage to 3 Hikvision Turbo HD cameras to nearly 5v and they still work perfectly..! No sign of any interference patterns at all, so that's why I'm at a loss as to where it is coming from...

Hi Tom. Why not? So long as the regulator gives out 12vdc for the cameras I don't see the problem..? Thanks, Martin

Yes, definitely full copper Cat5 cable (I don't do CCA). Yes I did try with just one camera and yes it was better so I guess it could be to do with the extra current drawn by 2 extra cameras and why it gets worse when IR cuts in at night...

I am using one Cat5 cable for every 3 cameras of my setup with AHD/TVI baluns each end. So that's 3 cameras per 3 pairs of each cable. The fourth pair of each cable I use to send 24v DC down and then regulate down to 12v DC to feed the 3 cameras. I know this is not exactly the industry standard way of doing things with CCTV but it did seem to work well...or at least I thought it did until I noticed the interference on some of the cameras..! One group of 3 cameras is a lot worse than the others, and it is the longest run too (approx 80 metres). I have attached a night-time screenshot, which is when the problem is much more noticeable. Thanks for your time, Martin

Hi guys, has anyone else had problems with wavy vertical lines appearing on some channels when using lots of cameras (> 10)..? I'll try to post a picture later if I get any responses... Thanks, Martin

Hi all, Just wanted to introduce myself to you guys. This forum seems to be the place to go for all kinds of CCTV help and guidance so rather than just searching for topics someone else has posted I thought I'd join the group! Kind regards, Martin