GB802800A - Improvements in or relating to coherent oscillator - Google Patents

Abstract

802,800. Valve oscillator circuits; radar. ROLLINSON, E. W. (General Precision Laboratory, Inc.). Dec. 28, 1949, No. 33164/49. Classes 40 (6) and 40 (7). An oscillator is periodically rephased so as to be in phase with the oscillations of each pulse of a train of R.F, pulse signals. The tank circuit of a Hartley oscillator has a valve connected across it and is either damped when the valve conducts or oscillatory when the valve is biased below cut-off. During the damped intervals the tank circuit is subjected to forced oscillations at the frequency and in phase with, the pulse oscillations and from the termination of the damped period and the commencement of the undamped interval, the tank circuit is maintained in oscillation at the same frequency and phase by the Hartley circuit. As shown, the tank circuit 30 and valve 29 comprise the Hartley oscillator and 30 also forms a cathode load to valve 11. The grid of the latter is adapted to receive three voltages, (a) a steady negative bias at 19, (b) an oscillation at the frequency of the R.F. pulse oscillation, and (c) a pulse of constant amplitude and of a duration approximately that of the R.F. pulse, which cause the valve bias to be normally below cut-off and above cut-off during the square-wave pulse (c). The voltage (b) is derived from a first output of the amplifier 10 to the input of which the R.F. pulse is applied and a second output from 10 is detected at 13 to produce the voltage (c). During the square-wave output (c), i.e. during the existence of the R.F. pulse, the valve 11 conducts and the circuit 30 is subjected to a forced oscillation at the R.F. frequency; at the termination of the pulse, valve 11 is cutoff and the valve 29 maintains 30 in oscillation at its existing frequency and phase until the next pulse commences and re-phases the oscillation in 30.