GB593137A - High-frequency signal-transmitters - Google Patents

Abstract

593,137. Radio transmitting systems. MARCONI'S WIRELESS TELEGRAPH CO., Ltd. Aug. 8, 1944, No. 15098. Convention , date, Dec. 29, 1942. [Class 40 (v)] A transmitter for high-frequency continuous wave communication comprises a source of H.F. oscillations, a load circuit, and means for applying the oscillatory power in widelyspaced short pulses to the load through a selective circuit to remove modulations of pulse frequency. As shown, two valves 1, 2 are connected in a conventional push-pull crossneutralization circuit. A tuned input circuit 3 is connected between the grids of the valves and their anodes are connected to a tuned output circuit 4, which is inductively coupled to a load through transmission line 5. Continuous high-frequency energy is supplied to input circuit 3 by source 6. Polarizing potentials are applied to the anodes of valves 1, 2 by pulse transformer 8, connected to the midpoint of the inductance of output circuit 4. The primary of transformer 8 is connected between the positive terminal of an H.T. supply and the anode of keyer valve 9. The pulse generator 10, which may be keyed by the signal to be transmitted, is arranged to provide pulses of short duration compared to the intervals between them. The voltages applied to the anodes of valves 1, 2 for the duration of the pulses are much higher than the continuous voltages which may be safely applied. Selective output circuit 4 is of the low-loss type, designed to pass the carrier frequency and signal variations of it, but to filter out any pulse frequency modulations. The output of carrier source 6 may be interrupted by a telegraph key, or modulated in phase or frequency ; or the D.C. potential applied to the pulser 9 may be amplitude modulated. The output of source 6 may be pulsed in synchronism with the anode voltages applied to valves 1, 2.