Structurally, the station consists of three main parts: the reception path, built on a chip TCA440, transmitting tract, performed by two-stage scheme of the transmitter, and a universal amplifier AF, who works at reception as UMZCH and transfer - as a modulation amplifier. Switching between "transmit-receive" made the switch S 1. The switch does not lock in the free state (as in the diagram) is in the "reception".In receiving the signal from the antenna through the contacts of S 1.4 and the capacitor C1 is fed to the input circuit L 1 C 2 is tuned to the carrier frequency. Dedicated signal through the coil L 2, due to the input of the symmetrical inverter circuits A1 (pins 1 and 2).In the local oscillator circuit works circuit L 3 C 4, tuned to a frequency oscillator and a quartz resonator Q 1, the resonance frequency is equal to twice the LO frequency, or below this frequency. Intermediate frequency signal is allocated in the loop L 4 C 6 and the coil due to the L 5 through the coupling capacitor C7 to the input of IF amplifier chip. This scheme is not used piezoceramic filter, this leads to a decrease in selectivity for adjacent channel, but allows you to choose a non-standard values of the intermediate frequency in the range 300 - 1500 kHz, on the basis of available quartz resonators for the transmitter and receiver.The output of IF amplifier circuit includes L 6 C 8 is configured to drive.The detector is made on a diode VD. IFA covered by a simple AGC system through the elements of R 4 and the joint venture. 34 voltage with volume control through R 5 S 1.2 to the input UZCH transistor VT 1 - VT 3, the output of which is on the speaker BA1.When you send an S in position opposite to that shown in the diagram. Through the contacts S 1.2 is connected to the input UZCH BM1 electret microphone, and the voltage output from the UZCH enters the base circuit of transistor VT 4 power amplifier transmitter, carrying out its amplitude modulation.The master oscillator of the transmitter is made on the transistor VT 5, its frequency is given by the quartz resonator Q 2, which may be on the carrier frequency or the frequency is two times lower. At the transistor VT 4 is the transmitter power amplifier, its output is on the P-loop C 19 C 20 L 8 and the antenna coil L 7 Extension.For all contour winding coils used radio frames to decoders from Core ZUSTST color TVs. For the receive path, these frames are taken from the screen for sending - no screens. Coil L 1 and L 3 each contain nine turns. Coil L 2 contains 3 coils wound on L 1.SEW wire diameter 0.31 mm, winding turn to turn. Coil L 4 and L 6 contain (for the intermediate frequency 465 kHz) to 120 turns of wire with a diameter of 0.12 mm SEW wound turn to turn in two layers. The coil is wound on the L 5 L 4, it contains 10 turns of PEV 0.12 mm in diameter, evenly spaced along the length of the winding L 4. The coil L 7 contains 17 turns, L 8 - 8 turns, L 9 - 9 turns. Winding wire is made, SEW diameter of 0.31 mm.DL choke wound on a resistor MLT-0, 5, 100 ohms, it contains 100 turns of wire with a diameter of 0.12 mm SEW wound vnaval.Throttle DL 2 is wound on a ferrite ring 400NN diameter 7-8 mm, contains 300 turns of 0.12 mm diameter PEV. Telescopic antenna is used, with a total length of 0.5 m from a portable radio.Each functional part of the radio station (receiver, transmitter, UZCH) is executed on a separate board. Size of printed circuit boards 52x76 mm, 40x73 mm and 30x42 mm, respectively.
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