GB425412A - Improvements in or relating to wireless and like receivers - Google Patents

Abstract

425,412. Valve circuits for wireless reception. ROBINSON, J., 76, Mill Way, Mill Hill, London. Sept. 9, 1933, Nos. 25023 /33 and 8326 /34. [Class 40 (v)] A wireless receiver comprises a mechanical resonator of low damping and a broadly tuned resonant circuit for receiving one side band of the transmission, the incoming signal being applied to both devices, the combined output of which is applied to a detector. Fig. 2 shows a superheterodyne receiver in which the intermediate frequency amplifier 12 comprises a broadly tuned circuit 13 feeding a detector 17 through an amplifier 20 and a phase or amplitude adjusting circuit 21. In parallel with these circuits is a piezo-electric crystal 9 tuned to the intermediate carrier, feeding the detector 17 through amplifier 22 and phase adjusting device 23 which may comprise a condenser 26 actuated by a portion of the output from 22. Alternatively the output of 22 may be used automatically to control volume in known manner, with suppression of output as by a rectifier 28 acting on the bias of the amplifier 18. Circuit 13 may be tuned to cover either of the two sidebands as by condenser 24 and switch 25 ; The piezo-electric crystal may be connected so as to derive its input from the circuit 13 instead of forming a branch circuit, Fig. 1 (not shown). Fig. 4 shows a receiver comprising high frequency amplifier 30 detector 31, and following amplifier 32. The high frequency input is branched to an oscillator detector 33 and thence to a crystal 34 tuned to the intermediate carrier frequency ; 35 and 36 are limiting and filter stages, and the output is fed back to the detector and thence to circuit 37 tuned to the original carrier frequency followed by a phase or amplitude adjuster 38. From thence the carrier component is fed back to the stage 30 to give increased selectivity. Specifications 201,591, [Class 40 (v)], 344,869, 366,568, and 396,772 are referred to.