GB541149A - Improvements in or relating to electric oscillation generators - Google Patents

Abstract

541,149. Valve generating circuits. MARCONI'S WIRELESS TELEGRAPH CO., Ltd. May 13, 1940, No. 8584. Convention date, May 13, 1939. [Class 40 (v)] An oscillation generator producing constant amplitudes, over a wide band of frequencies comprises a pair of valves T1, T2 with a frequency - determining circuit 6 coupled to the anode of one valve and to the control electrode of the other, and an impedance 3 common tc the cathode circuits of both valves, the arrangement being such that grid current does not flow in valve T1. The frequency - determining circuit may be a tuned circuit as in Fig. 1 or a condenser - resistance combination 24, 25, 26 in the multi-vibrator shown in Fig. 2. The output is taken from the circuit 9, 10 in Fig. 1 and from circuit 31 in Fig. 2, and locking voltages may be applied at 27, Fig. 2. In a combined oscillator and harmonic generator, Fig. 3 (not shown) a circuit tuned to the fundamental is connected to one anode, and a circuit tuned to a harmonic to the other. The coupling condenser 4, Fig. 1, may be replaced by a link circuit inductively coupling tuned circuits connected to the anode of one valve and the grid of the other, Fig. 4 (not shown). A crystal may be associated with the tuned circuit connected to the grid, Fig. 5 (not shown). Instead of a common impedance 3 separate impedances connected by a condenser may be used, Fig. 6 (not shown), and an inductance may be connected in series with the impedance 3 to " tune out" the ground capacity of the two cathodes at very high frequencies, Fig. 7 (not shown). Fig. 8 shows an arrangement suitable for testing the audio and radio response of wireless sets, a radiofrequency generator T1, T2 identical with that shown in Fig. 1 being modulated by currents from an audio-frequency generator T1<SP>1</SP>, T2<SP>1</SP> of similar type, the output circuit 9<SP>1</SP>, 101 being connected to the grid of valve T2.