GB574838A - Harmonic-frequency generator - Google Patents

Abstract

574,838. Valve generating circuits. HAZELTINE CORPORATION. Aug. 6, 1942, No. 11024. Convention date, Sept. 20, 1941. [Class 40 (v)] Pulses of narrow form and rich in harmonics are derived by peak rectification of waves of a secondary frequency produced by waves of a lower primary frequency, the pulses being at the primary frequency. In Fig. 1, primary oscillations from a source 10 are applied to a blocking oscillator 12 to give a saw-tooth output which is fed to the control grid of a valve 16 having in its anode circuit an inductance 17 tuned to a higher secondary frequency. The output from 16 thus consists of trains of damped oscillations of the secondary frequency succeeding each other at the primary frequency. Thus, after passage through diode 19, which passes only the positive peaks, the wave consists of positive pulses at the primary frequency and of duration less than half the period of the secondary oscillation. After amplification at 22 and passage through bandpass filters 28, 29, the output is passed to series resonant circuits 24 ... 27 'tuned to the desired harmonics, which may be selected by a switch 36 serving to connect an appropriate condenser 32 ... 35 to tune an inductance 37 to give the desired harmonic across output terminals 31. In the modification shown in Fig. 4, oscillator 41 has tuned grid and anode circuits so as to generate oscillations of a primary frequency determined by crystal 43. The output is fed through condenser 46 to valve 16 having a grid leak 46' which with condenser 46 has a time constant such as to give an anode current in the form of pulses at the primary frequency. These, by shock excitation of tuned inductance 17, give damped trains of waves at a higher secondary frequency which are fed to a peak rectifier 47 to give short pulses from which the harmonics are selected as in Fig. 1. In the arrangement shown in Fig. 6, the screen grid of valve 50 acting as an oscillator anode is tuned by circuit 54 to the primary frequency controlled by crystal 51. The plate anode is tuned by circuit 55 to a higher secondary frequency, such as the fourth harmonic, and these two frequencies are combined in the anode circuit to give a peaked wave form from which pulses are obtained by a peak rectifier 57. The harmonics are selected by means of a switch 60 which connects an appropriate condenser 61 ... 64 to tune an inductance 59 to the desired harmonic.