Abstract: A high frequency power amplifier comprises: an amplifier that amplifies signals received from a first input terminal and outputs amplified signals to an output terminal; a bypass route that connects a second input terminal to the output terminal without passing through the amplifier; a capacitor having a first end connected to the amplifier, and a second end connected to the output terminal; a first switch having a first terminal connected to the second end of the capacitor and to the output terminal, and a second terminal connected to the bypass route; an inductor connected in parallel with the capacitor; a second switch connected in parallel with the capacitor, and connected in series with the inductor; and a control unit that turns off the first switch and the second switch at a high power level and turns on the first switch and the second switch at a low power level.

Abstract: A high frequency power amplifier comprises: an amplifier that amplifies signals received from a first input terminal and outputs amplified signals to an output terminal; a bypass route that connects a second input terminal to the output terminal without passing through the amplifier; a capacitor having a first end connected to the amplifier, and a second end connected to the output terminal; a first switch having a first terminal connected to the second end of the capacitor and to the output terminal, and a second terminal connected to the bypass route; an inductor connected in parallel with the capacitor; a second switch connected in parallel with the capacitor, and connected in series with the inductor; and a control unit that turns off the first switch and the second switch at a high power level and turns on the first switch and the second switch at a low power level.

Abstract: This invention is to control the diffusion of C (carbon) from added graphite to particles of iron powder in the sintering to thereby improve the accuracy of dimensional change in the sintered body by using iron powder for powder metallurgy and a mixed powder thereof as a starting material in the production of sintered mechanical parts by adding the iron powder with Cu powder and graphite powder and companying and sintering them, in which 0.008-0.5 wt % in total of at least one element having a value of standard free energy of formation of oxide at 1000.degree. C. of not more than -120 kcal/1 mol of O.sub.2 is included in the iron powder and not less than 20% of the element is rendered into an oxide, or 0.01-0.20 wt % in total of an oxide powder of at least one element having a value of standard free energy of formation of oxide at 1000.degree. C. of not more than -120 kcal/1 mol of O.sub.2 is added to the mixed powder.

Abstract: The present invention relates to an amidothiophosphate derivative represented by the formula II: ##STR1## in which R.sub.1 is a methyl group or an ethyl group; R.sub.2 is a n-propyl group or a sec-butyl group; R.sub.3 is a C.sub.1 -C.sub.4 alkoxy group, a C.sub.1 -C.sub.4 alkylthio group, phenyl group or a phenoxy group; and n represents 1 or 2, and an insecticide, a nematocide and an acaricide containing the same as an active ingredient.

Abstract: A semiconductor substrate having first and second opposing surfaces is provided with a plurality of semiconductor elements having their electrodes arranged on the first surface. A plurality of small recesses are first formed in the second surface at locations opposite selected ones of the electrodes of the semiconductor elements. After the formation of the small recesses, the material of the substrate in and around the small recesses is etched away so that a larger recess encompassing the small recesses is formed and, at the same time, the small recesses are caused to extend through the substrate to thereby form through-holes which extend from the larger recess to the selected ones of the electrodes.

Abstract: A microwave transmit-receive switch for switching between transmission and reception of a microwave signal, includes a directional coupler, an antenna terminal connected with an input terminal of the directional coupler, a transmission terminal connected to the isolation terminal of the directional coupler, two switches connected between the respective output terminals of the directional coupler and ground, respectively, a quarter wavelength phase delay element connecting one output terminal to a reception terminal and a transmission line having no phase delay connecting the other output terminal to the reception terminal of the switching.

Abstract: A method for producing an aluminum nitride powder of superior sinterability of which steps are providing an aqueous boehmite sol having a pH of 1.2 to 4.5, mixing a carbon source material to the sol and drying the mixture. The mixture is sintered in a non-oxidizing atmosphere containing nitrogen or in a nitrogen atmosphere and finally decarbonized to obtain an aluminum nitride powder. The carbon source material is preferably a mixture of an organic carbon source material and a solid carbon powder. A predetermined amount of alpha-alumina may be added to the mixture.

Abstract: A method of heating a molten steel in a tundish for a continuous casting apparatus while the molten steel being introduced and circulated in a roundabout channel of a horizontal channel type induction heater attached to the side wall of the tundish. This relates to the technique in which electric power is applied to the induction heater depending upon the stored amount of the molten steel in the tundish, for instance, the power is increasingly supplied gradually in the case of the pouring at an initial stage, to effectively eliminate the current interference due to the pinching, and compensate the reduction in the temperature accompanied by the molten steel pouring at the time of the continuous casting.