There are at least two transmitters at two sites... not likely they're all bad. But... the owner has assured me they're clean and I haven't seen anything hokey on the spectrum analyzer from the repeater site.
Mike WM4B On Wed, Oct 28, 2009 at 2:46 PM, [email protected] wrote: Did you look a the output of the paging transmitters with a spectrum analyzer? Oct 28, 2009 06:29:13 PM, [email protected] wrote: A couple of weeks ago, our repeater system started to experience interference from a paging system. The repeater is on 146.850 (-600 KHz), with the antenna system about 120 feet up a water tower. The repeater itself is an Advanced Communications System KRP-5000 running 35 watts through a set of 4 WACOM cans. The feedline is 7/8" hardline feeding a DB-224. All jumpers are RG-214 MILSPEC with MILSPEC connectors. This system has been in service for years and has never given us any problems, and we are the only ones at the site. To be clear, the interference we are experiencing is clearly audible on the repeater input. I have the capability to monitor via telephone and have heard it on the receiver, and I've also traveled to the site and heard the interference on my mobile radio hooked to the repeater antenna. The interference is also audible on the input in various locations around town. Also, the interference can be heard on the input regardless of whether or not the repeater transmitter is on. It also continued to be present during several days of continuous heavy rain. The interference typically shows up at least once a day, although some days (rarely) it does not show up at all and other days it will show up several times. Lately, it's been making an appearance around 10 a.m. and hangs around for an hour or two. As it begins to disappear, it sounds as though it is moving off frequency. This interference has also been heard on at least two other repeaters in the area. One is about 22 air-miles from the 146.85 machine and is on 145.110 (-600 KHz). It has also been heard on or near the output frequency of that machine, and one evening I tracked it from about 145.120 to 145.190 as it swept through each transmission. The other repeater it has been heard on is 147.300 (+600 KHz). I also have reports from a neighboring county a ham/deputy sheriff there has been hearing it on VHF public safety frequencies. As you can see, it's all over the place. I've been working with the owner of a local paging company and we can clearly tell that the data we're hearing is coming from 152.480 and 462.775. He has two sites (about 20 miles apart) that simulcasts on both frequencies and when those transmitters are active it's easy to tell that the data is the same. He also tells me that he can key each transmitter separately and the data from each transmitter will be heard on our repeater. We also believe that there are other systems on nearby frequencies that are being heard on our repeater, specifically 462.850 and 462.925. I've run IMD numbers on everything I can think of, but can't come up with a common thread. For it to be moving all through the 2-meter band and for it to be mixing with several different frequencies, it seems to me that it's got to be very ugly and unstable. What am I missing here? Mike WM4B Messages in this topic (2) Reply (via web post) | Start a new topic Messages | Files | Photos | Links | Members Yahoo! Groups Change settings via the Web (Yahoo! ID required) Change settings via email: Switch delivery to Daily Digest
