The original commutator design flaws of CIRAD/SA(B) are analyzed, aiming at the rectifier unit of transmitters designed unreasonably, which led to higher transmitter faults. The flaws include：the lack of open phase monitoring function, which results in burn out fuse by high voltage power supply, being undetectable; high voltage striking is prone to happen if the impulse current is larger at the moment of applying high voltage; it is inconvenient to repair and cannot locate the fault of high/low voltage circuits rapidly. The new type of rectifier unit is developed, which improves the design of the unreasonable circuit and adds such new functions as rotary switch with repairing function, step stress outputting, and open phase and phase sequence protection, which can reduce transmitter lighter faults and improve the repairing efficiency of high voltage striking faults in a radar transmitter.