Most ethernet ports are keyed by a 25MHz crystal. What you and others describe is harmonics interference from this crystal. Which is common unfortunately especially on poe based equipment. Sometimes in bad cases you have to as well put ferruls on the power cable to the switch/poe injector as well as multiple ferruls at each end of every cat5 cable used.
/Eje Sent via BlackBerry from T-Mobile -----Original Message----- From: Gary Garrett <ggarr...@nidaho.net> Date: Mon, 30 Mar 2009 11:09:06 To: WISPA General List<wireless@wispa.org> Subject: Re: [WISPA] harmful RFI from ethernet to HAM RADIO? I went through this issue with a ham repeater at a mountain top tower. The repeater would key up and never let go as it saw some signal it thought was a user. I was in a metal cargo container and the repeater was in a frame building 20 feet away. I could turn off the ethernet switch and the interference would go away. I could leave the switch powered up and remove all the cat 5 cables to it and the interference would go away. It appears the ethernet switch was mixing several RF sources and emitting a sum or difference of the two (or more). I tried Ferrite rings on all cat 5 cables, shielded cable etc. Nothing really worked that well. Finally I moved 100' away to a different building on a different tower and no one is complaining now. Spacial separation seems to have fixed it. Kurt Fankhauser wrote: > Has anyone else here ever been co-located on a tower with a HAM radio > (144-148mhz) VHF repeater or perhaps even a commercial system in the 150mhz > band and gotten complaints that your Ethernet cable is causing them > interference on their repeater? We are trying to locate the source of noise > on an amateur radio repeater system locally and last time I went up on grain > leg there was a whole lot of Ethernet cabling strung everywhere and I've > read some links such as these. http://www.hamuniverse.com/linksys.html that > apparently some brands of equipment give out much more spurious emissions > than others. > > > > Also how did you work with the radio people to solve it? Seems to only be > apparent in the VHF band. > > > > > > > > Kurt Fankhauser > WAVELINC > P.O. Box 126 > Bucyrus, OH 44820 > 419-562-6405 > www.wavelinc.com > > > > > > > > > > -------------------------------------------------------------------------------- > WISPA Wants You! Join today! > http://signup.wispa.org/ > -------------------------------------------------------------------------------- > > WISPA Wireless List: wireless@wispa.org > > Subscribe/Unsubscribe: > http://lists.wispa.org/mailman/listinfo/wireless > > Archives: http://lists.wispa.org/pipermail/wireless/ > -------------------------------------------------------------------------------- WISPA Wants You! Join today! http://signup.wispa.org/ -------------------------------------------------------------------------------- WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/ -------------------------------------------------------------------------------- WISPA Wants You! Join today! http://signup.wispa.org/ -------------------------------------------------------------------------------- WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/
