3dk501d.pdf datasheet:

isc Silicon NPN Power Transistor 3DK501DDESCRIPTIONCollector-Emitter Breakdown Voltage-: V = 450V(Min.)(BR)CEODC Current Gain: h = 20(Min.)@I = 10AFE CCollector-Emitter Saturation Voltage-: V )= 1.2V(Max)@ I = 10ACE(sat CMinimum Lot-to-Lot variations for robust deviceperformance and reliable operationAPPLICATIONSDesigned for B&W TV horizontal output , regulated powersupply and power amplifier applications.ABSOLUTE MAXIMUM RATINGS(T =25)aSYMBOL PARAMETER VALUE UNITV Collector-Base Voltage 450 VCBOV Collector-Emitter Voltage 450 VCEOV Emitter-Base Voltage 5 VEBOI Collector Current-Continuous 20 ACP Collector Power Dissipation 100 WCT Junction Temperature 150 JStorage Temperature -55~150 TstgTHERMAL CHARACTERISTICSSYMBOL PARAMETER MAX UNITR Thermal Resistance,Junction to Case 1.25 /Wth j-c1