A simple test receiver. Scheme, description

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ENCYCLOPEDIA OF RADIO ELECTRONICS AND ELECTRICAL ENGINEERING
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A simple test receiver. Encyclopedia of radio electronics and electrical engineering

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Encyclopedia of radio electronics and electrical engineering / Civil radio communications

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To set up HF and VHF equipment (for example, frequency multipliers), as well as to quickly control the quality of the emitted signal of transceivers and transverters, you can use the proposed direct conversion receiver (Fig. 1). As a local oscillator, a signal generator is used (in my case, G4-107), the output voltage of which is fed to a detector assembled on anti-parallel diodes with an automatic bias circuit. Such a detector allows operation in a wide range of input and heterodyne voltages without a significant deterioration in the sensitivity of the receiver. ULF is made on an operational amplifier type 140UD6, UDU, etc.

(click to enlarge)

Gain control is carried out by resistor R6.

The absence of AGC and numerous side reception channels inherent in superheterodyne receivers makes it possible to fairly accurately compare the relative levels of signals and their harmonics.

The receiver is mounted on patches. The usual requirements for the installation of VHF devices are presented - the minimum length of the leads of the radio elements and connecting conductors.

For the 144 MHz range, the L1 coil has 4 turns and is wound on a mandrel with a diameter of 7 mm; for the 430 MHz range, it is a brass strip (Fig. 2), soldered at one end directly to the terminal of the capacitor C1, and the other - to a common wire.

Simple test receiver
Ris.2

The position of the tap is selected experimentally according to the maximum signal at the output of the OS.

Of course, the receiver will work on KB when connecting the input circuits of the appropriate ranges. It should be remembered that the frequency of the GSS should be two times lower than the frequency of the signal under study.

Author: S. Polzun (EW1RZ), Minsk; Publication: N. Bolshakov, rf.atnn.ru

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