this although it is weather radar will give an idea of the range it was operating over from Surathani to Butterworth.
Met there quote max range as 240 km. I would expect a lot better from military radar but physically at 415 km they claim to have painted at Butterworth and I think that is physically almost impossible unless the plane was flying very high level.
They did say Surathani radar detected it.
TMD Weather Radar