| 摘要 |
PURPOSE:To regulate the lower limit of a receivable frequency range adequately only by modifying a conventional device slightly, by applying a regulation voltage only when a band which should be regulated is selected. CONSTITUTION:A switching part 8 consists of switching transistors TR81 and 82, and the base end of the TR82 is connected to a switching terminal Bh for the VHF high band which should be regulated. Consequently, the TR81 turns on only during the reception of the VHF high band to extract a lower-limit regulation voltage Vhl. This voltage Vhl is further applied to the tuning-voltage application terminal 24 of a tuner 2 via a switching diode 9. Therefore, while the output voltage of a channel selection part 4 drops below the voltage Vhl, the diode 9 turns on to hold the tuning voltage at the voltage Vhl, thereby regulating the range of a lower-limit receivable frequency. |
