| 摘要 |
PURPOSE:To improve the cut-off characteristics of a low frequency side and a high frequency side, by providing an adjacent video trap circuit between an input or output winding forming a VIF BPF for a TV receiver and a parallel resonator and an adjacent audio trap circuit at the pre-stage of the BPF. CONSTITUTION:A shield case 13 having a BPF for VIF is sectioned with a shield plate 13a, 14 and a coupling window 15, 1/4 wavelength resonators 16, 16' one end of which is opened and the other end of which is connected to the case 13, an input winding 17 and an output winding 18 inductively coupled to the resonators 16, 16' are arranged at the space at both ends. A parallel resonator consisting of coils 19, 19' and capacitors 20, 20' is provided at two spaces at the center side, and auxiliary windings 21, 21' inductively coupled with the coils 19, 19' are provided. A coil 22 is inserted between the connecting point of the windings 21, 21' and the winding 17 to form an adjacent video trap circuit. Further, the pre-stage of the BPF is provided with an adjacent audio trap circuit comprising capacitors C9-C11, a resistor R3 and a coil L5, allowing to improve the cut-off characteristics of a low frequency side and a high frequency side. |
