| 摘要 |
782,676. Band-pass filters. SABA SCHWARZWAELDER APPARATE-BAU-ANSTALT A. SCHWER SOEHNE GES. May 4, 1954 [May 4, 1953], No. 12892/54. Class 40 (8). A band-pass coupling comprises at least two coupled resonant circuits and is characterized in that at least two compensation voltages are added to its output voltage in order to obtain two symmetrical zero-response positions. In the circuit of Fig. 2 the inductively coupled circuits 1, 2 are further coupled by means of coupling coils 4, 5 in series with a variable resistance 6 to provide a first compensating voltage. A further compensation voltage is derived from a coupling coil 7 and variable resistance 8. The zero response positions can be adjusted by means of the variable resistances 6, 8. In the arrangement of Fig. 3 three resonant circuits 1, 2, 3 are coupled inductively and the output applied to a diode 10. A first compensation voltage is derived from coupling coil 14 and is applied to the cathode of the diode. The second compensation voltage is derived from coupling coil 15, undergoes a 90 degree phaseshift in the circuit 16, 17, 18 and is applied to the anode of the diode. The centre-tapped output circuit 3 is neutralized with respect to the phase-shift circuit 16, 17, 18 by means of the equalizing capacitance 11. The zero response positions are balanced by adjustment of the couplings k1, k2 or the coupling coils 14, 15.
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