| 摘要 |
507,620. Valve circuits for wireless reception ; impedance networks. HAZELTINE CORPORATION. Sept. 28, 1938, No. 28206. Convention date, Oct. 16, 1937. [Classes 40 (iii) and 40 (v)] In a band-pass circuit, the voltage output, variable in phase with the frequency of the input, from a network C1, LI; C2, 2L2; C3, L3 is. combined with a voltage, the phase of which varies less rapidly with frequency, the constants of the circuit being such that the two voltages are in phase at the centre frequency and opposite in phase at the limiting frequencies of the band. The second voltage may be derived from a resistance 15 in the input circuit, Fig. 1, or from a coupling 28 to a further tuned circuit 25, 26 in the output of valve 14, Fig. 5. The arrangement gives a characteristic curve as shown at 20, Fig. 3, having a zero response at 10 kc. on each side of the centre, and this may be converted to the characteristic 22, Fig. 4, by increasing the coupling of the tuned circuits or by symmetrically detuning two of the circuits. In the arrangement shown in Fig. 5, inherent input capacity 30 in the valve 16 may be neutralized by a connection over a condenser 31 to part of winding 28.
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