Electronic tuner

Claim 1

An electronic tuner in which a resonant frequency is changed by changing a voltage applied to a variable tuning element; comprising: a band change-over switch base plate consisting of an insulating plate having a hole therethrough and a first circular rotary contact arranged around the hole, a plurality of first switch contacts arranged around the periphery of the first rotary contact, a plurality of second switch contacts aligned in a first direction with predetermined equal intervals and electrically connected to said first switch contacts, respectively, and a plurality of band contact groups, each group including a plurality of band contacts electrically connected with each other and supplied with a voltage and provided in cooperating relation with respective said second switch contacts, the band contacts provided in cooperating relation with one of the second switch contacts being aligned in a second direction perpendicular to said first direction; a resistance base plate consisting of an insulating plate having thereon a pair of first terminal members extended in the same direction as said first direction, and a plurality of resistor members extended in the same direction as said Second direction with the same intervals as said predetermined intervals of said second switch contacts between the first terminal members, said resistor members being supplied with voltages through said first terminal members; a resonant voltage change-over switch base plate consisting of an insulating plate having a hole therethrough and a second circular rotary contact arranged around the hole, a plurality of third switch contacts arranged around the periphery of the second circular rotary contact, and a plurality of second terminal members aligned in the same direction as said first direction with the same intervals as said predetermined intervals of said second switch contacts and electrically connected to said third switch contacts, respectively; a plurality of band change-over switches provided for respective said second switch contacts, each for selectively connecting the corresponding second switch contact to one of the band contacts aligned in the second direction in cooperating relation with said corresponding second switch contact so as to conduct the voltage applied to said one of the band contacts to the corresponding one of the first switch contacts for band changing-over; a mounting base plate, having a hole therethrough corresponding to the through-holes of said band-change-over switch base plate and resonant voltage change-over switch base plate, for mounting on one surface thereof said band change-over switch base plate on which said resistance base plate is mounted and on the other surface said resonant voltage change-over switch base plate; a plurality of slide members provided for respective said resistor members, each for taking out a predetermined voltage in accordance with the position thereof through sliding movement on the corresponding one of the resistor members; connecting means, perforating said resistance base plate, band change-over switch base plate and mounting base plate, for electrically connecting said slide members to said second terminal members, respectively, so as to conduct said predetermined voltages to respective said third switch contacts; a first rotary switch fixed to a rotary shaft inserted into said throughholes, for selectively connecting one of said first switch contacts to said first rotary contact so as to derive from the first rotary contact said voltage conducted to said one of the first switch contacts as a band change-over voltage to be applied to the variable tuning element; a second rotary switch, fixed to said rotary shaft, for selectively connecting one of said third switch contacts to said second rotary contact so as to derive from the second rotary contact said predetermined voltage conducted to said one of the third switch contacts as a resonant voltage to be applied to the variable tuning element for tuning; and driving means manually operable for driving said first and second rotary switches in a rotary movement for said selective connection.