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RADIO STATION ON THREE TRANSISTORS.

RADIO   ON   THREE   TRANSISTORS.

N. Marushkevich , Minsk

The radio station is intended for carrying out two-way communication in the range of 27 MHz with amplitude modulation. It is assembled on a transceiver circuit. The cascade on the transistor VT 1 serves both the receiver and the transmitter. The amplifier on transistors VT 1 and VT 2 in the receive mode amplifies the signal allocated by the receiver, and in the transmission mode modulates the carrier .

During installation, special attention should be paid to the arrangement of capacitors C10 and C11. They are used to prevent self-excitation. If self-excitation does occur, additional capacitors of the same capacity must be connected in addition.

About setup. It is very simple. First, using the frequency meter , the frequency of the transmitter is set, and then the receiver of another radio station is tuned for the maximum noise suppression and the loudest signal volume. The transmitter L1 is tuned by the coil L 1, and the receiver L 2 is tuned.

TECHNICAL DATA:

Supply voltage -   9-12 V.

The communication range in the open area is about 2 km .

The current consumption of the receiver is 15 mA,

transmitter - 30 mA.

Aerial telescopic -   0.7- 1m .

Body dimensions -   140x75x30 mm.

Тр 1 - any small-sized output transformer.

Ba 1 - any suitable speaker with a winding resistance of 8-10 Ohm.

Др 1 - ДПМ-0,6 or homemade: 75-80 turns PEV 0,1 on the resistor МЛТ 0,5 W - 500кОм.

The rest of the details are of any type.

Coils are wound on frames with a diameter 8 mm and contain 10 turns of wire PEV 0.5.

Printed circuit boards and circuit boards -   in Fig. 2     ð