Tim, I’ll bet someone in another apartment has a bad fluorescent fixture – it may be right on the other side of your wall, but if it’s really bad it will affect receivers within 200 feet or so. That would also explain why it interferes from sundown to 4 AM or so. Maybe it’s a plant-gro bulb and the guy is growing ganja . Or maybe a fish-tank light on a timer. Or an older CRT computer monitor.
When you hear bleedover of NOAA channels on an otherwise decent-performing scanner, unless the transmitter is faulty (doubtful) you may be close enough to be picking up signals on a “harmonic”. This phenomena happens on both AM and FM frequencies.
You will get bleedover anytime you are closely-proximate to a powerful transmitter, sometimes on two channels in each direction. When I’m at Rochelle RR park at night, the town’s police radio bleeds into my AAR frequencies. I’d guess the antenna is located on top of the city water tower across the street to the east.
Tim, the next time you drive up Route 53 in Itasca near the two large radio transmitting antennas, tune to 1440 on your AM car radio. You’ll hear WGN, which is 720 AM. The way the harmonic works is 720 x 2 = 1440 – given enough signal strength. It also works in the same location on 1560 because WBBM 780’s transmitter is there right next door (780 x 2 = 1560).
Here’s good list of causes:
Causes of radio interference
Poppa beat me to the punch, I was going to say the same thing about fluorescent lighting, and I will go further to say it is likely a defec
Well, whatever it is, I haven’t heard it for the last 2 nights. I had all the AAR channels that I have programmed in the scanner unlocked, and didn’t hear the noise… Although, I believe that I was hearing some distant dispatch to train communications, I had heard some locations that may have been down state, or in Indiana… I do remember hearing someone say something about “Fostoria” which I know is in Ohio…