Microphone Aero

The Scheme is a microphone multiplier with an automatic activation controller (ARU). It can be used in the transmitters of communications equipment. ARU works very well. The outlet level remains constant from the microphone to 3M. The adjustment takes place on T1 transistor through R2.

If there's no signal on the inlet, the tranzistor base through this sign is connected to the power source. The colloctor's point is about 2mA. Transistor T3 works as an active detector. When the signal comes at the inlet, depending on its level on the transistor T3 collector, the T1 begins to open and the flow of the manifold may fall to 100 mm. Thus, the control of the reinforcement is regulated by the flow of T1. The VD1 Diod has a limit function with too many signals. T2 is a surgeon with a common emitter.

At the outlet of the booster, the sound frequency of the PHF to 3K (C6, R8, C7). It's designed for SSB modulation. If the force is used for the FM modulation, the frequency of the filter shall be changed to 6 Kgz. The R10 Potentiometer can set the optimal level at the exit.

I've built a forcekeeper who's been working successfully at the 2M CCR for over a year. Figure 1 shows the dynamic microphone.