Frequency-modulated transmitter

专利名称：Frequency-modulated transmitter发明人：COOPER VICTOR JAMES申请号：US76275447申请日：19470722公开号：US2502557A公开日：19500404

摘要：610,951. Frequency modulation. MARCONI'S WIRELESS TELEGRAPH CO., Ltd.,and COOPER, V. J. April 15, 1946, No. 11545. [Classes 40 (v) and 40 (vi)] A valve circuitoperating as a variablemodulating reactance is associated with the tuned cathode circuitof an oscillator, the grid circuit of which comprises a coaxial tubular or equivalent line fordetermining the mean oscillation frequency. As shown in Fig. 1, the oscillator valves V1and the reactance valves V2 are arranged as push-pull pairs the oscillator grids beingconnected to tappings on a halfwave line 3, and the anodes earthed through a condenser9. The cathodes are connected to a tuned circuit 10, 11, across which are connected thegrid-cathode impedances of the reactance valves V2, whose anodes are connected to adamped tuned circuit 17 and are connected to the opposite grids by neutralizingcondensers NC. Modulating voltage applied to a central tap on the grid coil 14 producesa FM wave which may be taken off by coupling the load to the line 3 or to the circuit 10,11. The line 3 may be replaced by a quarter-wave line inductively coupled to the grids ofthe valves V1 ; and the valves V2 may be of the screengrid type and the neutralizingcondensers NC omitted, Figs. 2 and 3 (not shown). The modulating voltage may beapplied to the anodes or screen-grids of the valves V2.

申请人：RADIO CORPORATION

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