I would first mount them as far apart as possible and then in wireless conduct a frequency scan, if the other sector has a signal reading of less than -30db then you could have problems with co-location interference, i would suggest a read of posts http://forum.mikrotik.com/t/radio-card-rx-bandwidth/45267/1 http://forum.mikrotik.com/t/better-cpe-better-interference-protection-wanted/47205/1