SINGLE TUNING TRANSFORMER

摘要

PROBLEM TO BE SOLVED: To provide a single tuning transformer for building up a lower cost single tuning circuit by decreasing the number of coils in use. SOLUTION: An input winding N1, a tuning winding N2, and an output winding N3 are wound on a plurality of winding grooves provided to a bobbin 2 integrated with an insulator base 1 made of a resin or the like, and integrated with each other while arranging the number of turns of the windings and a degree of interference among them. A coupling coefficient of each winding is selected so that relations of K12K23 hold, wherein K12 is the coupling coefficient between the input winding N1 and the tuning winding N2, K13 is the coupling coefficient between the input winding N1 and the output winding N3, and K23 is the coupling coefficient between the tuning winding N2 and the output winding N3. The magnetic flux density of the coil is increased by screwing a screw core 3 to the axis center of the bobbin 2. A pot core 4 made of a magnetic body is covered to the bobbin 2 to apply magnetic shield to the outer circumferences of the input winding N1, the tuning winding N2, and the output winding N3. Further, the whole including the base 1, the bobbin 2, the screw core 3, and the pot core 4 is contained in a conductor case 5 to apply electrostatic shield to the outer circumferences of the input winding N1, the tuning winding N2, and the output winding N3. A plurality of terminal pins P are implanted to a bottom side of the base 1, and left and right case legs 51, 52 suspended from the side faces of the case 5 are fitted to the case 5. COPYRIGHT: (C)2006,JPO&NCIPI