GB364637A - Improvements in or relating to short wave oscillation generators - Google Patents

Abstract

364,637. Valve generating circuits. MARCONI'S WIRELESS TELEGRAPH CO., Ltd., Marconi House, Strand, London, and GILL, E. W. B., Merton College, Oxford. Oct. 8, 1930, No. 30166. [Class 40 (v).] In a short-wave valve oscillator, the normal oscillatory circuit comprising the anode-grid capacity C a n d a short-wave coil L1, Fig. 1, is shunted by a second circuit L2 the wave-length of which is greater than, but less than twice, that of the normal circuit, the object being to increase the energystoring capacity of the oscillator without increasing the voltage swing on the valve electrodes, or substantially increasing the wave-length of the oscillator. As shown in Fig. 5, a push-pull pair of valves VI, V2 have their plates connected by a shortwave, coil L1, and their grids by a similar coil L1<SP>1>. The two coils and the plate to grid capacities constitute the frequency-determining circuit. The added circuit comprises two pairs of Lecher wires L2, L2<1> with adjustable bridgepieces B, B1 to the centre of which the plate and grid voltage sources are connected. Best results are obtained when the bar B is removed three-eighths of a wave-length from the plates. The bar B1 may serve as a fine adjustment for wave-length. In the single-valve oscillator, Fig. 6, a large condenser C1 and an inductance L1 are in the frequency-determining main circuit, whilst the added circuit comprises Lecher wires L2 (or a coil whose natural wavelength is three-halves the working wave-length), and a large condenser C2.