I just bought an old Uniden Bearcat BC140 10 channel programmable
scanner at a garage sale. I know almost nothing about scanners. I
bought a telescoping antenna at Radio Shack that seemed to fit into
the antenna outlet on the scanner. I found an AC adaptor that works. I
programmed some local police frequencies in that I got about 6 years
ago. When the scanner is scanning through the stations, it stops on a
couple of the channels, and there is noise (not squelch noise), but I
can't hear any talking and I'm trying to figure out the problem.

Do police frequencies change regularly so that my old frequencies are
no longer right?

I live in a rural area and the police departments that are programmed
in are about 15-30 miles away. Am I too far away from those towns? I
also live in a house covered with metal siding and roofing.

Thank you for any help you folks can provide!