"The unknown aircraft's signal was sending out intermittently, on and off, and on and off," the spokesman said. The Thai military lost the unknown aircraft's signal because of the limits of its military radar, he said.
That sounds a lot more like an equipment failure than someone deliberately turning off the transponder.
Nope, that sounds like Thai Military Primary Search Radar was painting the MH 370 at the limit of the Radars range hence it was intermittently painting the target.
"Sending out" is surely transponder, not primary radar receiving a reflected signal from a skin paint? The "limits" referred to could as easily be display limitations as anything - the radar display only goes to <insert figure here>.
But then reporting in a second language has dogged pronouncements since Day 1.