The selectable Ka segments for sti-r:
"Ka1 (33.392 - 33.704) ON or OFF
Ka2 (33.704 - 33.896) ON or OFF
Ka3 (33.886 - 34.198) ON or OFF
Ka4 (34.184 - 34.592) ON or OFF
Ka5 (34.592 - 34.808) ON or OFF
Ka6 (34.806 - 35.166) ON or OFF
Ka7 (35.160 - 35.383) ON or OFF
Ka8 (35.378 - 35.618) ON or OFF
Ka9 (35.595 - 35.835) ON or OFF
Ka10 (35.830 - 35.998) ON or OFF"
(ka7 may be slightly off, I copied this from the online manual and don't have the typo correction insert so tried to guesstimate it)
With that said, driving in US, is there any point keeping any of them other than 2 (33.8), 5 (34.7), and 8 (35.5)? In other terms, I'm not sure if the increased range given reduced frequencies to scan is worth it versus say the device potentially being off on the frequency and missing it or the like.