GB393983A - Improvements in wireless receiving circuits - Google Patents

Abstract

393,983. Wireless receiving circuits. HINTON, N. P., 57, Broughton Avenue, Finchley, London. Nov. 17, 1931, No. 31876. [Classes 40 (iii) and 40 (v).] A circuit' arrangement tunable over a range of frequencies and having for each tuning position two frequencies of re-. sponse comprises two tuned circuits LI, Kl, L2, K2 having no mutual inductance coupling and associated by a coupling circuit such that a constant frequency differenceismaintained. Fig. 5 shows a coupling comprising condensers kl, k2 and inductances l1, l2 which may be interchanged, Fig. 1 (not shown). In a modification, Fig. 3, the two coupling circuits are arranged diagonally as shown so that the series mode of oscillation excludes the coupling circuit while the figure of eight oscillation is through K1, l<1>2, k<1>2, K2, l<1>1, k<1>1, instead of one mode of oscillation being through the coupling inductances and the other mode through the coupling condensers as in the previously described arrangements. In a further modification, Fig. 4, in which the coupling inductances l1, ¢ l1 and l2, ¢l2 are respectively tightly coupled so that the inductances ¢l1 and ¢l2 carry twice the current that the inductances l1 and l2 carry when oscillating in the figure of eight or bridge mode. The arrangement may be used to give band-pass coupling and the band width may be made adjustable by making the coupling circuit adjustable. The coupling unit,may be made as a separate unit and be separately screened. Fig. 5 shows the application to a supersonic heterodyne receiver in which local oscillator energy is supplied at LO, the received carrier at RC while the output energy of beat difference frequency is taken off at OT. The potentials of the couplings are arranged as shown so that re-radiation is avoided.