Ken, I built a UHF repeater in Orlando, FL which had this problem after I sold it to a subsequent owner. The site was an 18-story office building roof where I had secured a rent-free lease, and we were the roof's lone RF occupant. My group built and installed a weatherproof cabinet and AC power.
The repeater's subsequent owner was approached by a Part 15 wireless company with an offer of a free broadband connection at the repeater in exchange for housing a UPS and other equipment in the cabinet. Needless to say, li'l ol' 442.250 acquired IRLP and APRS super-powers, but the kind of interference you describe was an issue. >From a legal standpoint, we were a licensed operation, so under Part 15, he >bore sole responsibility for resolving the interference. >From the landlord's perspective, he was paying rent and we were not. Nuff said? Anyway, there were apparently off-the-shelf filters available for the wireless nodes which completely solved the problem on the repeater input. But they apparently compromised wireless coverage, (or the wifi guy thought they did, in a sort of reverse-placebo effect,) so he kept taking them off. Eventually the problem was resolved permanently by four hurricanes in one season, working in concert with his wind load profile. He could no longer justify constant antenna replacements. So, long story short, there apparently are high-pass or bandpass filters out there for wifi radios. You'll want to do some research on their insertion loss. The experience in Orlando also suggests the issue is related to the radios themselves, not the CAT5, because we had it routed right through the repeater cabinet. I don't know if the ethernet cable was shielded at that site or not, however, because I'd already left town. Hope that helps! 73, Paul, AE4KR ----- Original Message ----- From: Ken Arck To: Repeater-Builder@yahoogroups.com Sent: Friday, February 22, 2008 12:57 PM Subject: [Repeater-Builder] WiFi interference to UHF? I've started deploying WiFi nodes (500 mw radios) at my various sites (so far, only one is done) and I've noticed some interference to one of my UHF repeaters at that site. The interference is only noticable on weaker signals (so obviously the interference itself isn't all that strong) that manifests itself as a low level pulsing or clicking sound "under" the UHF user. The WiiFi radio/router is mounted at the top of the tower and fed power via the CAT5 cable (POE). The antenna for the WiFi unit is in faily close proximity to the UHF antenna too. I'm thinking moving the WiFi antenna a bit down the tower might solve the problem. Then again, I'm not yet sure if it's an RF thing or the CAT5 cable itself radiating (it ain't shielded) Anyone run into this before? Ken ---------------------------------------------------------- I am Shakespeare of Borg. Prepare to be or not to be
