RFI: CCTV Power Supply Causing 9dB Plus Noise

We recently added another set of surveillance cameras and DVR to expand the coverage around the property. After we set the system up we decided to expand it a little more and added 4 more cameras to it. At this point we needed a more powerful power supply that would connect to these 8 cameras and provide the needed voltage and current.

We purchased this power supply: http://www.amazon.com/gp/product/B005AXDVUS

Noisy Power Supply

 

 

 

 

 

 

When it arrived I removed the 2 stock power supplies and put this one in line. It appeared to work fine. I didn't use the radios much for a few days. When I finally turned my 890 on I noticed a large amount of noise. I switched through all bands and had a constant 9dB+ noise level. I thought maybe the bands were just crap because of the rain and storms that were active in the region. Next day the same thing. On and on for about a week when I decided I have had enough. I called a couple friends to check band conditions and they reported everything as normal, quiet.

First thing that came to mind was that power supply. I turned the radio up so I could hear it from the other room, went in and unplugged the power supply and it got quiet in a hurry! I swore a little bit about the power supply's heritage and came back to sit in the shack and think a few minutes. I needed that surveillance system online and didn't want to wait for more mail order/amazon stuff. I dug around in my closet and the other room and found my stack of spare power supplies, the kind you hook mobile radios etc up to.

I chose a 12v 10AMP supply, wired up a connector to hook into the power splitter, then tested the supply under a load in the shack. Everything checks out good. I drag it in the room with the DVR, plug it in the wall and connected the power splitter up. Flip the power switch and… It works great! Cameras came back on instantly and absolutely no noise/RFI! I'll just leave it there and get some use out of it for a change.

A little long winded but you get the point. Avoid using cheap switching power supplies where ever possible. Especially if you're a radio geek.

About the Author

kd0cq
Chris - KD0CQ (formerly KB0TLW) has held an amateur (ham) radio license since 1994 and is stubbornly grasping onto his Advanced class operator status. His professional experience includes Network and Systems Administrator, Network Security, and Electronics Engineer. Sometimes even a little bit of web development. mail: chris at kd0cq dot com

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