If I have followed the thread correctly, this interference happens from "either" of the paging transmitters, not just one or the other.
I would suggest you check to see if there is a TV linear translator very nearby it could be the source. --- In [email protected], "Mike Besemer \(WM4B\)" <mwbese...@...> wrote: > > Joe, > > > > The problem isn't traffic dependant (10 am being a busy time), as I monitor > on and off all day and there is PLENTY of traffic all day long. It seems to > have more to do with temperature. You can clearly hear the signals come on > and fade off frequency. > > > > It's also easy to hear which transmitter is sending the pages. I have two > dual band radios in my vehicle. Typically one is on the repeater output, > one on the input, one of VHF paging and one on UHF paging. It's also been > confirmed by having the owner send test bursts by specific transmitters. > > > > The other two UHF frequencies are also paging transmitters. > > > > Good thoughts about the transmitter self-oscillating when unkeyed... that's > another road we can go down. > > > > Speaking of going down roads. what I really need is more help! Several of > our club members are engaged in assisting, but what I really need is a > dedicated team of folks. Having to work for a living is taking a serious > bite out my tracking time! > > > > 73, > > > > Mike > > WM4B > > > > From: [email protected] > [mailto:[email protected]] On Behalf Of Joe > Sent: Wednesday, October 28, 2009 11:51 PM > To: [email protected] > Subject: Re: [Repeater-Builder] Pager Interference to 2-meter & VHF Public > Service Band > > > > > > Hello Mike. > > The first clue is that the signal is moving up and down the 2 meter > band. This would tell me that something not frequency controlled is > causing the interference. Not frequency controlled would mean that the > transmitter is not crystal or GPS locked to a specific frequency. Now, > something that is frequency controlled may be involved with the IMD mix, > but the signal that is free running is possibly causing an IMD mix to > drift. I have seen this happen in a PA when it was NOT transmitting. > We had a case of a paging transmitter PA that would go into self > oscillation when it was not keyed by the exciter. The PA had power to > it at all times and it would create interference when it was idle. > > Some random thoughts: > > Your paging company signal may be mixing with it, but they may not be > the culprit. > > 10AM can be busy time for a paging company, so the fact that it happens > around that time would not be unusual. > > How do you know the data is from a specific paging company? Did you > listen to their signal and the interference at the same time? Is it > exactly the same? > > He says that he has remote control of the transmitters. What happens > when he shuts them both off? As someone else pointed out, does he have > a link frequency that he ties the sites together with? The link > transmitter may be causing the interference, or be part of the RF mix. > > An IMD program will be useless to figure the IMD of a drifting > transmitter that is part of a mix. > > You said 462.850 and 462.925 are also involved. What is on those > frequencies? Who is on these frequencies and how are they involved? > > A lightning hit may have caused this all to happen. > > In my last job I troubleshooted lots of interference. You really need > to take an antenna and directional find the source of the interference. > It is time consuming, but will lead you to the physical source of the > interference. Don't be fooled that it is positively the paging > companies fault, as it may just be a mix in some other service PA. The > last one I found was interference on a 53.85 Mhz repeater. At first, > the culprit seemed to be the NOAA weather station on 162.55Mhz. NOAA > weather audio was coming through the repeater crystal clear. It turned > out to be a telemetry station PA that was mixing 4 X 53.85 - 162.55 = > 52.85Mhz. The mix was exactly on the input! The telemetry station was > owned by the water company that allowed us on the site, so we ended up > moving the repeater to 53.71Mhz. We could have pushed the water company > to fix their equipment, but probably would have been asked to leave the > site. Sometimes diplomacy rules. > > I worked for paging companies for quite awhile and know that they get a > bad rap, probably rightfully so for the most part. This sounds like the > paging company is willing to work with you. My gut feeling is that you > are going to find something else causing the problem. Again, diplomacy > rules. > > 73, Joe, K1ike > > Mike 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. T >
