Most of the high level ones along I-25 and E470 (Bald north, Horsetooth, Thorndin, etc).What site(s) are you monitoring on Colorado DTRS? In the Fort Collins area, I monitor the Horsetooth site with Normal (default?) filter.
Same here, and I second what Jon said. The need for filters is location dependent, unfortunately the SDS can have major issues with adjacent frequencies depending on the time of day, phase of the moon etc. In my experience SDS intermod is more common with UHF, VHF and Airband, not so much with 700/800.Using an SDS100, I'm using all the default settings.