Guess I need to get a list of active repeaters in the area or bring my spectrum analyzer (bench queen) up and start sniffing. I'm wondering if this is just a case of 2-system products or if there's other systems involved that might (also) be dirty, e.g., a commercial high-band system. It'd be worth looking for rust and corrosion (dioding points) on antennas, connectors and mounting brackets. Michael, if there's something I can do to help, let me know. 73 gerry n5jxs On Fri, May 24, 2013 at 8:48 AM, Laws, Peter C. <[log in to unmask]> wrote: > The 88 repeater is off the air temporarily for technical reasons. I'm > in-touch with Mr Salem and will keep the club up to date on progress. > > -- > Peter Laws / N5UWY > National Weather Center / Network Operations Center > University of Oklahoma Information Technology > [log in to unmask] (Remote) > College of Architecture, Regional and City Planning, MRCP '16 > ________________________________________ > From: Micheal Salem [[log in to unmask]] > Sent: Monday, May 20, 2013 02:52 > To: Laws, Peter C. > Subject: 88 Repeater and Broadband noise on 2 meters > > Peter: > > I wanted to let you and the club know that I had to take the repeater out > of service. Ken N5KUK alerted me to some hum on the repeater. He also > indicated that he had been tracking some broadband noise. I am not sure it > was not coming from 88. The repeater is not really usable at this time. > > I went over to check it and tried to figure out what was wrong. I also > took some measurements. I will study them tomorrow when I check my > repeater maintenance logbook at the office. I can't tell if there is a > problem with the xciter or there is some oscillation in the receiver front > end because the first limiter is bouncing all around. There is hum when > the reciever is unsquelch, but there is more hum than usual on the xmtr > squelch tail. > > I checked my two local supplies that run the micor squelch card and the > repeater controller. They had the correct DC voltages and neither of them > had more than .003 volts of AC on them, so I don't suspect those as the > power supply problem. It must be internal to the receiver and is probably > some internal oscillation. > > I finally decided to take the repeater off. Unfortunately, I will not > have any time to work on it until Friday as I have a very important brief > due on Thursday. I am going to take the service manual for the repeater > with me to the office. > > I have a VHF Micor (and also a UHF) repeater as well as an MSR2000 VHF > repeater in the 148 Mhz government band. I intended to use one of these as > an eventual replacement. I wanted to take out the old Motrac and put the > new repeater in the outdoor cabinet so that it would stay clean. Not sure > if I can do that yet. > > I will try to keep you and the club informed of the repeater status. I > apologize for this problem. > > 73, > > Micheal N5MS > > On 5/19/2013 10:52 PM, Micheal Salem wrote: > Ken: > > Thank you for your email. I noticed the hum noise a couple of times on > 88. At first it sounded like skip because it occurred early in the morning. > > A long time ago I had broadband noise on 88. I traced it to a leaking > CATV line over on Acres street before calling the cable company. > > I also had a key up on the repeater when another repeater was on the air. > I finally figured out that it occurred when someone keyed up on another > repeater while driving close to the 88 repeater site. Their uplink mixed > with the other repeater's downlink in the repeater's receiver and if > somebody keyed the 88 repeater, the 88 transmitter frequency mixed with the > other frequencies and produced a 600 khz offset close to 146.28 Mhz that > would stay on until one of the frequencies went away. > > But the problem you describe sounds like there is something wrong in the > tuning of the 88 transmitter which is producing some spur that is causing > your problem. Have you looked at 88 with a spectrum analyzer and seen any > spurs? I have a Tektronix 2710 at the office and an HP8558B here at home > and I will try to take a look at it. > > I just tested the repeater using my TYT radio and it does seem to have a > problem. > > I am going to take it off the air and try to go over to the repeater site. > If I can't figure out what the problem is, I will leave it off the air. I > have some work that I have to get done by Thursday and will probably not be > able to look at it again until Friday. > > Thanks for writing. If you have any other thoughts about this, please let > me know. > > 73, > > Micheal N5MS > > > On 5/19/2013 7:16 PM, [log in to unmask]<mailto:[log in to unmask]> wrote: > Mike, > We have been chasing some broadband noise that is obliterating both the > input and output of the 147.06 repeater. It seems to peak about 147.220 but > I found that it only occurs when the 146.88 repeater is keyed up. Also > 146.88 has a lot of what sounds like 60 cycle noise on the carrier. Maybe a > power supply problem there. > > Ken Brown, n5kuk > -- Gerry Creager NSSL/CIMMS 405.325.6371 ++++++++++++++++++++++ “Big whorls have little whorls, That feed on their velocity; And little whorls have lesser whorls, And so on to viscosity.” Lewis Fry Richardson (1881-1953)