KD501 Bipolar Transistor

• Type: NPN
• Collector-Emitter Voltage, max: 40 V
• Collector-Base Voltage, max: 40 V
• Emitter-Base Voltage, max: 5 V
• Collector Current − Continuous, max: 20 A
• Collector Dissipation: 150 W
• DC Current Gain (h_fe): 15
• Transition Frequency, min: 2 MHz
• Operating and Storage Junction Temperature Range: -50 to +155 °C
• Package: TO-3

Here is an image showing the pin diagram of this transistor.You can replace the KD501 with the 2N3771, 2N3771G, 2N3772, 2N3772G, 2N5301, 2N5302, 2N5302G, 2N5303, 2N5685, 2N5685G, 2N5686, 2N5686G, 2N5885, 2N5885G, 2N5886, 2N5886G, 2N6282, 2N6282G, 2N6283, 2N6283G, 2SC2434, 2SD797, BDX69, BDX69A, KD502, KD503, MJ11012, MJ11012G, MJ11028, MJ11028G, MJ14000, MJ14000G, MJ14002 or MJ14002G.