| 摘要 |
PURPOSE:To attain the sufficient suppression up to a high frequency signal, by operating a switching element so as to attenuate an output signal to an amplifier means and making successively plural amplifier elements of the amplifier means into non-operating state. CONSTITUTION:A switching circuit 4 consists of resistors (R)1, R2 and a transistor (TR)1, an amplifier circuit 5 comprises R3-R10, a capacitor (C)2 and the TRs 2, 3 and an output stage circuit 7 is made up of R11, R12, C3, C4, TR4 and TR5. A voltage almost equal to ground potential is given from a synchronism detecting circuit 3 to the circuit 4 under a normal state and the TR1 is brought into non-operating state. Thus, a signal transmitted from a phase synchronism oscillating circuit 2 is amplified at the TRs 2, 3 and outputted via the circuit 7. A negative base potential is given from the circuit 3 to the TR1 under the state of out of synchronism and the TR1 is brought into the operating state. Then, the signal of the circuit 2 is absorbed in the TR1 and the TRs2- 5 are brought into nonconductive state and cut off at the same time. |
