GB538389A - Improvements in or relating to wireless receivers with bandspread tuning - Google Patents

Abstract

538,389. Tuning wireless receivers. PHILIPS LAMPS, Ltd. Feb. 26, 1940, No. 3574. Convention date, Feb. 28, 1939. [Class 37] A plurality of tuning dials arranged rectilinearly are traversed by the same pointer, the control members being designed to cause the main tuning member and the pointer to move slowly over the required frequency band and the tuning,member to move more rapidly.from one frequency band to another. In the arrangement, Fig. 1, the pointer 38 is moved over three dials 47 by an endless band 39 driven by a drum 35 with a smaller drum 34 over which a cord passes from a spring 37 to a point 36 on a lever 30. This lever is pivoted at its ends to members 52, 42 adjustable by push buttons 54 and a knob 43 ; and a point 33 on the lever is connected by a cord 32 to the sliding member of a tuning condenser 31. The frequency band is selected by setting the left end of the lever 30 to one of the points 40, 50, 60 by the appropriate push button 54. This moves the tuning condenser 31 rapidly to the desired band. Tuning within the selected band is then performed slowly by the knob 43. In another arrangement, Fig. 2 (not shown), a single operating knob operates a rack carrying the pointer and three transverse rods of different lengths co-operating in succession with a cam on the movable electrode of the tuning condenser. The Specification as open to inspection under Sect. 91 comprises also : (1) arrangements for tuning the input and output circuits of a mixing valve, each circuit having three condensers selected by a switch, and a variable condenser or a variable inductance ; (2) arrangements of aligned and superimposed rectilinear dials illuminated by separate lamps according to the frequency .band selected ; (3) an arrangement in which a tuning circuit includes five adjustable condensers selected by a switch in parallel with a combination of a main variable tuning condenser in series with fixed condensers selected by a switch, the two switches being coupled together and operated automatically when a pointer connected to the main tuning condenser passes from one dial to another of a set of rectilinearly disposed dials, the pointer co-operating with five contact strips connected to a relay through a five-point switch to operate a motor one switching step at a time ; and (4) various minor modifications of the arrangements described above. This subject-matter does not appear in the Specification as accepted.