| 摘要 |
PURPOSE:To give a limitation, when necessary, to the tuning range of an electronic tuner, by limiting the variable range of the tuning voltage to be applied to a varactor diode. CONSTITUTION:A VHF high band is selected by a tuner control circuit 3, and then the maximum value of a maximum limit voltage setting variable resistance VR1 is set at the upper limit frequency along with the minimum value of a minimum limit voltage setting variable resistance VR2 set at the lower limit frequency, respectively. Accordingly, an electronic tuner 1 is impossible to receive an outside cable band. Then a VHF low band is selected by the circuit 3, and thus no selection signal VH is applied to a tuning limiting circuit 11. As a result, no limiting action is given to the tuning voltage. |
