KColeman, can you explain about the notch filter? What is it, and what does it do?
Hopefully I can explain this. A notch filter is a filter designed to deeply attenuate a frequency or range of frequencies in order to eliminate interference in your scanner. The FM filter that I mentioned notches out the FM broadcast band of 88~108 MHz, with the filter centered on 98 MHz.
The filter installs in-line between your antenna and your scanner.
In my case, this filter has far exceeded my expectations. Since I listen to VHF & UHV air, the VHF side is like night and day in the difference. I won't tell you that I hear signals farther away, but the signals I do hear, sound better. As an example of the difference it has made for me. I live approximately 35 miles from Montgomery Regional Airport. While doing a service search on the air band, the scanner stopped on the ATIS frequency... I had never heard this before from home and I now routinely hear the ground side of the tower and approach.
You can find these filters and other filters at Universal Radio, Scanner Master, and Grove Enterprises.
Good Luck & Good Scanning,