I have been using, for over a year, a Diamond 220R mini-discone on a BCT15X, and a COMPCtenna w/ ground-plane on my BCD436HP; both antenna/scanner sets are located inside my top floor apartment; antenna are located adjacent to windows. Both combinations did quite well until about two weeks ago when I lost the ability to pickup a public safety, trunked system in SLC (AC33). The BCT display shows that it is searching for the control channel. I have checked the programming on the BCT and it is correct. I took my BCD mobile yesterday using the COMPACtenna on a mobile mount and I picked up the site with no problem; its performance was actually amazing. Afterward, I again tired the COMPACtenna with the base mount and I could not receive the site. Interestingly, I hooked my basic telescoping antenna up to the BCD, again inside the apartment at the same location, and it did a pretty good job of picking up the site; I am stumped.