GB244169A - Improvements in receiving apparatus for high frequency signalling systems - Google Patents

Abstract

244,169. Hinton, N. P., and Metropolitan-Vickers Electrical Co., Ltd. Sept. 11, 1924. Thermionic amplifiers and detectors; receiving- sets, construction of. - A receiving system for high-frequency signalling comprises an aerial inductance 12 connected in the grid circuit of the first valve 16, which has its plate coil 17 coupled to the tuned grid coil 21 of the second valve 24, and the plate circuit of this valve includes a reaction coil 25 which is movably mounted so as to give reaction on to either the coil 12 or the coupled coils 17, 21. When in position for maximum positive reaction on one coil it gives reverse reaction on the other; whilst in mid-position it gives reverse reaction on both coils. The fixed coupling between the coils 21, 12 is also arranged to give reverse reaction effects. The diagram, Fig. 1, shows a reflex circuit, the low-frequency patentials arising across the resistance 26 in the plate circuit of the detector valve 24 being passed through a condenser 27 and highfrequency choke 28 to the grid of the first valve 16. The telephones 18 are in the plate circuit of this valve. Fig. 3 shows the coil unit, the fixed coils 12, 17, 21 being housed in recesses in an ebonite block 40. The movable reaction coil 25 is mounted on the side remote from the aerial coil 12, and its holder 47 is pivoted so as to swing in an arc from beneath the coil 12 to beneath the coils 17, 21. The coil unit may be provided with contacts to engage with springs mounted on a wireless receiving set, thus enabling different units arranged for different bands of wave-length to be interchanged.