Abstract: A power amplifier of the present invention includes (i) a bipolar transistor for amplifying a signal supplied via a base terminal, so as to obtain an amplified signal, and outputting the amplified signal via a collector terminal and (ii) an inductor between an emitter terminal of the bipolar transistor and a ground. An inductance between the emitter terminal and the ground is larger than a parasitic inductance between the emitter terminal and the ground between which the inductor is not provided. This allows the bipolar transistor to increase an output power without increasing an emitter area. As a result, the present invention makes it possible to provide a highly efficient high-power power amplifier.

Abstract: A variable impedance circuit includes a capacitor and a MOSFET and is connected between the base of a bipolar transistor and a ground node. The capacitor acts to the open for a direct-current component. The MOSFET varies impedance for an alternate-current component. A base voltage ration portion includes first and second resistors, which set a bias applied to the base of the bipolar transistor. More specifically, the base voltage generation portion divides an operating voltage supplied through a voltage terminal by a ratio of the first and second resistors to generate a base voltage of the bipolar transistor.

Abstract: The invention provides a novel magnetically traceable or detectable explosive blended with a magnetic ferrite powder which facilitates the detection of the misfired explosive, e.g. dynamite, remaining in the field after blasting by a magnetic means but not to adversely affect the stability of the explosive. The ferrite powder is freed of any free alkalinity on the surface before blending with the explosive either by washing with water, neutralization with a dilute acid, reaction with an acid followed by washing with water or neutralization with an alkali and/or by coating with a polymeric material on the particles. The most efficient method for the coating of the ferrite powder with a polymeric material is the in situ polymerization of a radical-polymerizable monomer in contact with the ferrite particles in the presence of hydrogensulfite ions and the explosives blended with such a polymer-coated ferrite powder retain their stability even after a prolonged storage.

Abstract: The invention provides a novel magnetically traceable or detectable explosive blended with a magnetic ferrite powder which facilitates the detection of the misfired explosive, e.g. dynamite, remaining in the field after blasting by a magnetic means but not to adversely affect the stability of the explosive. The ferrite powder is freed of any free alkalinity on the surface before blending with the explosive either by washing with water, neutralization with a dilute acid, reaction with an acid followed by washing with water or neutralization with an alkali and/or by coating with a polymeric material on the particles. The most efficient method for the coating of the ferrite powder with a polymeric material is the in situ polymerization of a radical-polymerizable monomer in contact with the ferrite particles in the presence of hydrogensulfite ions and the explosives blended with such a polymer-coated ferrite powder retain their stability even after a prolonged storage.