| 摘要 |
A rotary tuning mechanism comprises an integral dielectric structure including a gear wheel with a first set of teeth extending from a first face surface and a second set of teeth extending radially from a circumferential surface, a shaft attached to the gear wheel and a spacer ring attached to a second face surface of the gear wheel. The gear wheel is sandwiched between two planar housing sections with the spacer ring urged against a first planar section and the first set of teeth urged against detent ball bearings supported within respective apertures in the second planar section by a flat spring and symmetrically disposed with respect to the axis of the gear wheel and shaft. An AFT defeat switch is mounted to engage the second set of teeth. The housing is mounted on a printed circuit board containing a rotary switch for selecting various tuning circuits associated with respective channels. A dielectric channel indicator wheel fits over the rotary switch. The shaft extends through an aperture in the printed circuit, rotary switch and channel indicator wheel and engages keyed portions of the latter two. The entire mechanism is mounted at the side of a television receiver with the axis directed sidewardly in a planar subassembly formed of a dielectric material having an aperture just slightly larger than the channel indicator wheel so that the face of the channel indicator wheel and planar subassembly form a side portion of the cabinet of the receiver.
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