I have the Samsung SIR-T150 and live in an apt between 116th & 124th close to Juanita Bay.
I am currently using the RS DB and can get 4,5,7,9 (both) with moving the antenna. It sits on top of my speaker right now.
I did get 13 when I first started by moving it closer to the window but since they don't have much in the way of HD I am not that concerned. I still have cable at the moment.
I was going to try the 4228 but may try the 4221 instead (less obtrusive) in or out of the apt.