| 摘要 |
1,074,156. Transistor frequency changer circuits. SIEMENS A.G. Sept. 23, 1964 [Sept. 24, 1963], No. 38713/64. Heading H3T. A transistor self-oscillating frequency changer circuit is provided with two series connected R.C. networks R 1 C 1 , R 2 C 2 connected to the emitter; network R 2 C 2 having a smaller time constant than network R 1 C 1 so as to avoid hunting. The H.F. signal is fed from the secondary of R.F. transformer L and is mixed with the oscillator signal to produce an intermediate frequency ZF. The frequency of the oscillator is determined by the line circuit Z and is controlled by C 3 . The emitter voltage is fed in at 1 and the resistors R 1' R 2 stabilize the circuit against temperature variations. The decoupling capacitor C 2 provides the circuit with a low input impedance at the intermediate frequency. |
