Patent GB-814294-A (GB)
Title: Improvements in or relating to tuning arrangements for radio receivers
IPC: H01F21/06
Filed: 1955-09-10
Abstract: 814,294. Adjusting radio apparatus. COLE Ltd., E. K., and YATES, J. K. Sept. 10, 1956 [Sept. 10, 1955], No. 25939/55. Class 40 (5). A tuning arrangement for a radio receiver comprising permeability tuned tuning coils comprises a rotatable turret having a plurality of positions in each of which a corresponding adjustable stop is positioned to engage a stop formed on a carriage carrying the tuning cores of the coils and spring-urged so as to bring the stops into engagement and means whereby on actuating the mechanism for effecting a change in tuning, the carriage is withdrawn to disengage the stops, the turret is turned through one step in its rotation and the carriage released to bring the stop on the carriage and.a successive stop on the turret into engagement. The actuating mechanism may either be operated directly by means of a push-button or through the intermediary of a solenoid. In the arrangement illustrated the tuning cores V are mounted upon a plate H forming part of a carriage G which is normally urged to the right by a spring I so as to bring a projection L from the carriage G into engagement with a stop M mounted on a screw-threaded rod N forming part of the rotatable turret. The turret comprises five such rods each carrying a stop M, although only one is shown, and a rotatably mounted axial spindle O. The arrangement also comprises a solenoid, Fig. 4 (not shown), whose movable core is also mounted upon the plate H so that on the operation of the solenoid the carriage is moved to the left thus disengaging the projection L and stop M. A further projection e on the carriage G rotates the bell-crank lever a in an anti-clockwise direction, thus causing that portion of the lever in contact with a ratchet wheel d mounted on the shaft O to move upwards and rotate the ratchet wheel and hence the turret through one step. Thereafter the solenoid is released and the carriage G moves to the left until the projection L engages with a fresh stop M. Notches formed in the periphery of one end-plate of the turret serve to retain the turret in each of its successive positions by engagement with a resilient catch secured to the lower wall D of the apparatus. In order to permit continuous manual tuning and also adjustment of the preset tuning positions a knob f mounted upon a shaft P carrying a sun-wheel R is provided. The sun-wheel co-operates with five planet wheels S (only one being shown) and each is fixed upon a corresponding one of the rods N. On rotation of the knob f the rods N are all rotated and initi.- ally all the stops M rotate with the rods without longitudinal motion. However, the stops M all contain a lengthwise slot so that shortly after it begins to rotate the stop in engagement with the projection L is arrested by a catch i, Fig. 2, which is mounted on the carriage G. Thereafter further rotation of the knob f causes longitudinal movement of the stop and a consequent variation of the tuning setting of the receiver. One of the five positions of the turret may be reserved for continuous tuning in which case the corresponding rod N may have a coarser thread than the others.