KST  -  Series DataSheet
KST42  -  High Voltage Transistor  -  Fairchild Semiconductor Corporation  -  Small Signal Transistor

NPN Epitaxial Silicon Transistor
VCBO Collector Base Voltage : KST42  300V: KST43 200V
VCEO Collector-Emitter Voltage : KST42  300V: KST43 200V
VEBO Emitter-Base Voltage 6 V
IC Collector Current 500 mA
PC Collector Power Dissipation 350 mW
TSTG Storage Temperature 150 °C
RTH(j-a) Thermal Resistance junction to Ambient 357 °C/W