Mathew, I tried to find a licensed user of 155.190 MHz in an area 40 miles north of your QTH, around Michigan City, but found none. I also couldn't find a coordinated repeater on 147.285 MHz in that area. Please identify by callsign the repeater on 147.285, and where it is located. I simply assumed that "here" refers to your QTH. Are there any other transmitters at that location? Can you identify what Sheriff Department is using 155.190 MHz, and where it is located? I ask these questions because I suspect that the Sheriff's signal may be mixing with a third carrier and that station may be generating IM, unbeknownst to the Sheriff. This third station may very likely be at the same site as the Sheriff's repeater, and I can look at such candidates only if I know where each site is located. It may be very instructive to set up a spectrum analyzer to see what signals are present when the interference occurs.
Some questions come to mind: 1. Is the signal from the Sheriff repeater being heard by the complainers' radios directly, or is the Sheriff's signal being repeated over the 147.285 machine? 2. If the Sheriff's signal is being repeated on the 2m machine, what happens when the repeater transmitter is shut off? That is, can you still hear the Sheriff's signal on the 2m repeater's monitor speaker at the site, with the TX off? 3. Is the interference also heard over a commercial-grade radio? This might eliminate an image reception issue. 4. What are the details about the 2m repeater? (Make/model of receiver, transmitter, duplexer, filters, antenna, etc.) 5. When the interference is heard, is it a mixture of voices or tones, or is just the Sheriff dispatcher heard clearly? 73, Eric Lemmon WB6FLY -----Original Message----- From: [email protected] [mailto:[EMAIL PROTECTED] On Behalf Of n9lv Sent: Tuesday, May 02, 2006 8:22 PM To: [email protected] Subject: [Repeater-Builder] OT: 155.190 intereferes with Ham Radio Frequencies I've have been asked to assist with an issue in a town about 40 miles from here regarding a commercial system that is causing interference with Ham Radio. At best, the information that I have thus far, is that there is a repeater that is owned by the county sheriff's department, this repeater itself is on the output of 155.190, and is said to not be causing interference. The only time that it interferes with the hams in the area is when the city talks on the repeater for 911 dispatches. At this time I do not know how much power or what type of radio they are using, antenna height, or brands. The radios thus far that is receiving the interference, from two locations, one about a mile away and the other about a block away, is the IC-2100H mobile radios, and an ADI AT600 handi talkie. There has been other complaints, I'm supposed to get additional information this weekend, and possibly make a trip up there to hear the interference. Questions I have is, what should I be looking for? What avenues should be taken? I do know that the Chief has been notified of the situation, but refuses to see a problem and has done nothing to rectify the situation. At this point, I do know they say that on the receive of 147.285 that there is noted a nearly full scale signal, making it impossible to hear the repeater that is about 25 miles north of there, of which is on a 400 ft tower, classified as a large scale repeater. Thanks Mathew Yahoo! Groups Links Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
