Controllable HF input circuit - has HF rectifying diode which is not biased, so that following transistor is controlled even at low HF signals

摘要

The h.f. input stage has a circuit part rectifying h.f. control voltages and amplifying them, and is designed for generation of a sufficiently large control signal even when h.f. control voltages are small. Anode and cathode potentials of an h.f. diode (10) rectifying the h.f. control voltage, are adjusted by a diode (11) and a transistor (12) operated at saturation, so that the diode (10) is not biased, and the transistor (12) is driven even at low h.f. control voltages. A small resistor (9) is connected between the diode (10) and the base terminal of the transistor (12).