Hello, Another funny interference story, I may have put it on here before but it bears repeating. One of the Police repeaters in the area that the shop I worked for and maintained was getting a stable, slightly off-frequency signal modulated with a 1000 Hz tone but without CTCSS. It did not key up the repeater but interfered a lot with the HT's they were using. This had been going on for 2 or 3 days. The FCC was called and could not find it. The manager of the Water Department was a Ham and knew of another Ham that made a hobby of finding these problems. This guy had a van with a 22 element home made Yagi mounted on the top with a shaft going down into the cab, he used a pair of Vice Grips as a handle! Anyone know who this "Guy" is? He is also famous for the power supplies he builds.
The Ham did what the FCC could not, he was able to see the direction of the signal from the Repeater Site. He took off in that direction with the FCC in tow. He located the building where it was coming from, the Motorola manufacturing facility in Fort Worth, Texas. The Guy took his portable tracking unit with the FCC man again in tow and entered the building. They introduced themselves to the receptionist, about one minute later 5 or so VP's appeared. The guy was then released to find the interference. They got to the room where it was coming from, there was a Cushman CE-3 turned up all the way (without the attenuator pad in-line) with a coax with the center conductor exposed and wrapped around a broom handle and pointed out the window directly toward the repeater site. Do you think some Motorola employee got a ticket sometime? Paul -----Original Message----- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] Behalf Of [EMAIL PROTECTED] Sent: Wednesday, January 11, 2006 3:48 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] OT - funny interference story Back around 1990, we were having a problem on VHF with an interfering signal that drifted ever so slowly back and forth across 2-Meters and the VHF business band. One of the radio techs in our radio shop had a 2-Meter Repeater nearby, which would wind up being keyed up for long periods of time with a dead carrier as this interfering signal slowly drifted across the repeater's input frequency. He got out an IFR Service Monitor, and tracked the signal to an apartment building about two blocks away from the radio shop. He then contacted the FCC, and they contacted the apartment building Manager. We met about 9:00 A.M. a few days later, at the entrance to the apartment building with the apartment Manager, the FCC Inspector, and the IFR. After contacting the residents that were still in the building (many had already left for work for the day), we went to the main electrical panel for the building and started shutting off circuit breakers to sections of the building. One breaker made the interfering signal go away, so that narrowed it down to just a few apartments on one upper floor. We knocked on the door of the first apartment, and the Resident let us in after the apartment Manager explained who we all were, and what we were looking for. We unplugged just about everything in the apartment, but the signal remained. We then went to the apartment across the hall. No one was home, so the apartment Manager opened the door with his master key, and we all went in. The first thing we tried was unplugging the aquarium heater, since they're often such a terrible electrical noise maker, but the signal was still there. Nothing else that we unplugged seemed to make the interfering signal stop, until we unplugged one AC cord going to something on the stereo system. It was an amplified FM antenna, which was a unit about a foot tall. The gain control on it was cranked up to about 8 out of 10, causing it to go into oscillation and radiate over a wide area. The FCC Inspector unplugged it completely, coiled up the AC power cord, and left it on a living room chair with some very important-looking paperwork which basically said "DO NOT USE", "CONTACT US IMMEDIATELY". The apartment manager promised to follow up with the owner of the unit with the details of our "visit". The problem never returned! Larry -----Original Message----- >From: JOHN MACKEY <[EMAIL PROTECTED]> >Sent: Jan 10, 2006 5:00 PM >To: Repeater-Builder@yahoogroups.com >Subject: [Repeater-Builder] OT - funny interference story > >This is a funny story from the Broadcast Engineering mail list... > >-----Original Message----- >From: [EMAIL PROTECTED] >[mailto:[EMAIL PROTECTED] Behalf Of Ron Castro >Sent: Tuesday, January 10, 2006 12:31 PM >To: Broadcast Radio Technical Forum >Subject: Re: [RT] Re: Local interference issues and lawyers > > >We had a case many years ago here in Santa Rosa where an FM station moved >its transmitter and a neighbor, who was a wealthy doctor, started >complaining of major TV interference on all channels, and he demanded that >the station stop transmitting and go away. The station owner could see that >doctor's TV antenna was in very poor condition, and he offered to replace it >for free, the was turned down. The doctor complained bitterly and regularly >to the FCC until an inspector finally came out. The inspector pronounced >the FM station clean, but he could see some other source of local >interference in the area on his spectrum analyzer. Turns out it was the >doctor's Radio Shack pre-amp on his broken-down antenna that had gone into >self-oscillation and was cleaning out the whole neighborhood! > >By this time, the FCC had such a craw-full of the doctor that they issued >him an NAL for causing interference. > >Ron Castro >Chief Technical Officer >Results Radio, LLC > > > > > > > >Yahoo! Groups Links > > > > > > 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/
