| 摘要 |
PURPOSE:To conserve the power consumption of the power source by varying the resistance value of a variable resistance circuit inserted into a power source circuit of a power amplifier according to the selection of a swith for limiting band. CONSTITUTION:When a switch SW2 is turned to the position for bypassing a low pass filter LPF, a resistor R4 is selected and when it is turned to the position of the low pass filter LPF, a resistor 5 is selected while the resistance value of the resistor R4 is set at a value lower than that of the resistor 5. With such an arrangement, when the band is not limited, the power is amplified in a better linearity to a high pass frequency where deflection electrodes P1 and P2 give a low impedance. When the limiting of the band is performed, current energizing a transistor Q1 decreases to save the power consumption of the power source. This can achieve the conservation of the power consumption of the power source. |
