Heathkit MP-1 Mobile Power Supply Heavy duty transistor power supply furnishes all the power required to operate both the MT-1 Transmitter and MR-1 Receiver. Uses two 2N442 transistors in a 400 cycle switching circuit supplying a full 120 watts of DC power. Under intermittent operation it will deliver up to 150 watts. Chassis size is 9 1/16" l x 4¾" w x 2" h Operates from 12-14 volt battery source. Circuit convenience provided by self-contained relay which allows push-to-talk mobile operation. Weight: 7 lbs