| 摘要 |
460,186. Impedance networks. MULLARD RADIO VALVE CO., Ltd., and CLARK, R. G. July 16, 1935, No. 20297. [Class 40 (iii)] A band-pass filter for use in radioreceivers and the like comprises a pair of tuned circuits L1 Cl, L2 C2 coupled by a capacity which can be varied so as to vary the band-width while the middle frequency of the pass band remains constant. The coupling condenser has two semicircular fixed plates P1, P2, and three semicircular movable plates mounted on one shaft, of which the middle one P3 is set at 180‹ to the two outer ones P4, P5 which are connected together electrically. The sum of the direct capacity between the fixed plates P1, P2, the capacity between the same plates via P4, P5, and the capacity between either of these plates and earth is constant.
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