GB493056A - Improvements in or relating to tuning indicators and dials for radio and like apparatus - Google Patents

Abstract

493,056. Adjusting wireless apparatus. MARCONI'S WIRELESS TELEGRAPH CO., Ltd. March 30, 1937, No. 9039. Convention date, March 28, 1936. [Class 37] [Also in Group XL] A wireless receiver is provided with a frequency indicator comprising a rotatable scale or a pointer co-operating with a pointer or scale and a cathoderay resonance indicator mounted at the axis of rotation of the scale or pointer. In Figs. 1 and 2 the dial 40 carrying the frequency scale is mounted on a hub 30 rotatably mounted in apertures in the mounting plates 22, 24, on which is also fixed a gear wheel 36 engaging and driven by a toothed disc 80 mounted on the tuning condenser spindle 14. The hub 30 also carries an auxiliary dial 42 detachably mounted thereon and marked with local station names which are aligned with the corresponding frequencies on scale 40. A cathode-ray resonance indicator 46 of the " Magic eye " type is mounted on the chassis member 44 with its forward part inside the hub 30 and its forward surface flush with the dial. The dial pointer 55 is fixed with respect to the rotating dial 40 on which the wavelength or frequency scales for the various wavebands covered are marked on concentric scales. The pointer is mounted on a plate 61 which slides vertically under the control of the waverange switch spindle 20 by means of a rack 59 and pinion 57, thus to co-operate with the waveband scale in use. The cathode ray indicator is so arranged that the dark unilluminated portion 50C, which narrows to a minimum at exact resonance, is in line with the pointer 55 so that the wavelength scale and the indicator may be simultaneously observed during tuning. The tuning control shaft 70 drives the toothed disc 80, and thereby the condenser spindle 14 and dial 40, by means of a friction driving device comprising a U- shaped member 76 in the opposite limbs of which two steel balls are mounted so as to be freely rotatable. The disc 80 is forced between the balls which roll between the disc and the spring cheeks 78 of a spool member fixed to shaft 70 when the latter rotates, and the drive is thus transmitted to the disc 80. In the modification shown in Fig. 5, the dial 87 is normally fixed and carries a number of semicircular scales 87a, b, c, one for each waveband, while the pointer 85, together with the cathoderay indicator 89, is rotated by cord and pulleys from the condenser shaft 117 and control knob 123. On operating the waveband switch 99 the appropriate scale is brought to the pointer 85 by linkwork 103 and shifting gears 105. The shadow line of the resonance indicator 89 is aligned with the pointer 85 as shown in Fig. 1. Specifications 480,441 and 481,790, [Group XL], are referred to.