CyberPower BC1285C Interference

In May of 2006 I bought a UPS to protect my shack against short power outages. After comparing a few models in the store I settled on the BC1285C by CyberPower. It had a nice blue informative LCD display and although it worked well as a UPS, it caused horrible interference. I made some recordings with a computer and a scanner to make the interference audible and I also took pictures of the TV (channel5) to document the interference. Below you will find a sample of each.

The Sound sample below starts with the UPS off and not plugged in. You only hear the video carrier of Channel 5 (CBS in this case, 77.25MHz). After 5 seconds the UPS is plugged in, but in the off position. Nothing is connected to the UPS. Then the UPS is disconnected from the mains again after 5 seconds, and then plugged in for another 5 seconds. The wideband noise is probably caused by a switching mode charger and can be received all the way up in the 2 meter Amateur Radio Band.

CyberPower BC1285C Charger Interference Sound Sample (775kB)

The image below shows what the interference looks like on TV in the next room. The TV already has ferrite cores on the power line, yet that is not sufficient to suppress the interference. Without those cores the interference would probably be a lot worse.

When the unit is turned off with nothing connected it also emits an audible hiss, much like that of escaping gas. When the unit is turned on, with still nothing connected, the hiss disappears.

Perhaps I just had a defective unit. However, I wanted to document the interference here on my website so that other Amateur Radio Operators may be made aware that UPS devices can cause interference and what it sounds and looks like.

I contacted the manufacturer about this and they made sure I could return the unit to the store I bought it from for a full refund. With the refund I bought an APC Back-UPS XS-1200 that has served me very well, interference free!

73,
--Alex KR1ST