| 摘要 |
RCA 70,954 PLANAR PRINTED CIRCUIT BOARD ARRANGEMENT USEFUL IN THE UHF PORTION OF A TELEVISION TUNER A tuner for a television receiver comprises a circuit board formed by a slab of dielectric material having conductors located on one side and discrete components mounted on the other so that it may be readily assembled and soldered. Some of the conductors are arranged to form capacitors and distributed parameter inductors. In the UHF portion of the tuner a strip-like conductor and a wider ground conductor are spaced apart in parallel relationship. The length of the gap between the strip-like conductor and the ground conductor is selected to provide inductive reactance in the UHF band. A slot is cut, punched or otherwise formed through the dielectric material in the gap between the strip-like conductor and the ground conductor to increase the Q (the figure of merit inversely related to loss) of the inductor at the upper end of the UHF range. In addition, the slot significantly improves thermal stability of the inductor. Furthermore, the combination of the slot associated with the inductor and another slot utilized to mount a varactor diode, coupled to the inductor to form a tuned circuit, determines the length of the gap. In a preferred arrangement, the two slots are punched by a unitary die to minimize the variation of inductance values from one tuner to another due to registration errors. |
