The PH series of radio remote control systems are wireless units that are operable with one hand. These units can perform both the ON/OFF control and the proportional control which are required for construction vehicles and industrial machinery. The transmitter is held in the hand for ease of operation, and the ON/OFF switch and trigger lever used for proportional control signals can be operated simultaneously. For instance, users can operate the trigger lever using their index fingers while operating one of the toggle switches using their thumbs at the same time. Specified low-power type of radio signals is used for longrange applications, obviating the need for any license in Japan and making it possible to use the system immediately.