| 摘要 |
PURPOSE:To make the adjusting operation easy and to use diods with different characteristics, by providing a variable adjusting circuit variably adjusting the operating range of a varactor diode between the varactor diode of a tuning circuit and a variable voltage circuit. CONSTITUTION:A series circuit consisting of a plurality of varactor diodes 2a and 2b and variable capacitors 3a and 3b is connected in parallel with a tuning coil 1 of a tuning circuit and a voltage is applied to the diodes 2a and 2b from a variable voltage circuit 5. Variable adjusting circuits 6 and 7 variably adjusting the operating range of the diodes 2a and 2b are connected between the circuit 5 and the diode 2a or the diodes 2a and 2b. The circuits 6 and 7 are constituted with variable resistors R6a and R6b, and R7a and R7b and a bridge circuit is constituted with a variable resistor R5 of the circuit 5. The tuning operation can be made easy and diodes with different characteristics can be used. |
