GB657328A - Superregenerative wave-signal amplifying system - Google Patents

Abstract

657,328. Valve super-regenerative circuits. HAZELTINE CORPORATION. Oct. 22; 1948, No. 27536. Convention date, Nov. 28, 1947. [Class 40 (v)] The frequency of oscillation of a superregenerative amplifier is changed at a predetermined time after the quench wave has caused the amplifier to have a negative resistance. The main part of the oscillation may therefore be made to occur at a different frequency from that of any preceding or succeeding tuned circuits and "ringing" and re-radiation from the aerial may be avoided. A saturation mode super-regenerative amplifier 10 has an oscillating circuit 12 regeneratively backcoupled to the cathode and a cathode selfquench network 16, 17. The input is fed to coil 42 from a tuned aerial circuit and the output is obtained from coil 44. A reactor valve 33 has a grid blocking circuit 34, 35 which allows the valve to become conductive when the resistance of the tuned circuit is negative and oscillations have commenced to build up. The output circuit of this valve which is tuned to a different frequency feeds a phase quadrature voltage back to the main oscillatory circuit and causes the oscillatory frequency to change to a different value. A grid-biassing network 14, 20, 21, 22 stabilizes the average quench frequency as described in Specification 646,331 or when frequency-modulated signals are being received, is adjusted to reduce the effects of amplitude modulation. For frequency-modulated signals a circuit of the type described in Specification 657,329 may be used, Fig. 5 (not shown), in which the detector comprises a high Q circuit tuned such that one of the side-band components of the quenched output oscillation near to the frequency F2 falls on the sloping side of the frequency response curve of the tuned circuit. These components which are spaced by an amount equal to the quench frequency bear the frequency modulation of the incoming signal and the component selected is thus converted to amplitude modulation. Frequency drift of this component may be prevented by using an A.F.C. voltage derived from the detector to adjust the quench frequency, and the frequency modulation may be compressed to keep the deviation within the limits of the tuned circuit of the detector by feeding back the modulation in negative phase to the grid of valve 10 to control the quench frequency. Separate quench sources may alternatively be provided, Fig. 3 and 4 (not shown), the reactor valve being supplied with a quench frequency voltage through a timing circuit (e.g. a delay or waveshaping network).