This only happens when taking off from a road FARP. If I start in the air or from an airfield then the SAM radars operate as expected. In the case when they don't radiate, they do rotate. I've attached trk files for all three instances. Note, when I took off from the airfield the terrain masked me up until the last several seconds.
TO from road.trk
Airstart.trk
TO from airfield.trk