BDW51 Bipolar Transistor

• Type: NPN
• Collector-Emitter Voltage, max: 45 V
• Collector-Base Voltage, max: 45 V
• Emitter-Base Voltage, max: 5 V
• Collector Current − Continuous, max: 15 A
• Collector Dissipation: 125 W
• DC Current Gain (h_fe): 20 to 150
• Transition Frequency, min: 3 MHz
• Operating and Storage Junction Temperature Range: -65 to +200 °C
• Package: TO-3

Here is an image showing the pin diagram of this transistor.The complementary PNP transistor to the BDW51 is the BDW52.You can replace the BDW51 with the 2N6471, 2N6472, KD502 or KD503.