Encyclopedia of radio electronics and electrical engineering / Civil radio communications

 Comments on the article

The proposed device is designed to work together with the transverter described in the article "Stationary FM transverter 144/27 MHz"(" Radio ", 2000, No. 2, pp. 60, 61). It allows you to improve its performance.

The operation of the transverter showed that when it is docked with CB radio stations, a problem arises due to the fact that these radio stations, as a rule, have an output power of 4 W or more. Although the transverter can operate with input power up to 6 W, pumping it with a strong signal often results in out-of-band emissions. To eliminate this shortcoming, it is necessary to reduce the input power supplied to the transverter. Some CB radio stations have this feature. However, most of them do not. The way out of this situation may be to install a special matching device between the radio station and the transverter.

This device should reduce the transmit power ("TX") to the transverter to an optimum level. This can be done, for example, using a simple resistive attenuator. But in this case, the reception signal will be weakened, which can lead to a loss of sensitivity, and, in addition, the power entering the antenna in the CB band will decrease. Therefore, such an attenuator must be made automatic so that it is connected only when working in conjunction with a transverter in the "TX" mode.

A diagram of such a device is shown in the figure. It contains a low-pass filter with a cutoff frequency of about 40 MHz on C1L1C2 elements, which additionally suppresses signal harmonics during transmission and attenuates the signal of the transverter's local oscillator during reception. An adjustable switchable attenuator is assembled on resistors R1-R3, R5 and relay K1. The control unit is assembled on the transistor VT1 and the diode VD1. The relay is powered from the transverter via the connecting cable and L2 choke.

When the transverter is turned off, power is not supplied to the matching device and the attenuator is turned off, so the signal passes without loss to the transverter and from it to the CB antenna. When the transverter is turned on, the supply voltage is supplied to the device. In the receive mode "RX" transistor VT1 is closed, so the relay is de-energized and the attenuator is disabled.

When switching to the "TX" mode, the transmitter signal through the capacitor C3 enters the diode VD1, is rectified and fed to the base of the transistor VT1, it opens and the relay K1 is activated. With its contacts, it connects an attenuator, and the transmitter signal at the input of the transverter is attenuated. The trimming resistor R2 can be used to adjust the attenuation within 5 ... 10 dB, with a satisfactory agreement. At the end of the transmission, the transistor closes, the relay de-energizes and the attenuator turns off.

The device can use transistors of the KT315, KT312, KT3102 series with any letter index. Diode VD1 - series KD521, KD522; VD2-any low-power rectifier. Capacitors - K10-17, KM. Trimmer resistor R2 - SPO, SP4, constants - MLT, S2-33. Resistor R1 is made up of two MLT-2 connected in series, 10 ohms each. Relay K1 - RES47 with a winding resistance of 600 ohms (passport RF4.500.417). Coil L1 is wound with wire PEV-2 0,8 on a mandrel with a diameter of 4,5 mm and contains 10 turns; L2 - inductor DM-0,1 with an inductance of 100 μH or more, it can be wound on a ferrite ring 2000NN with a diameter of 5 ... 10 mm with a PEV-2 0,1 wire; the number of turns is 15-20.

It is necessary to refine the transverter - between the XW1 socket and the SA1.1 switch contact it is necessary to install a capacitor with a capacity of 1000 cOpF (KM, K10-17), and install a DM-1 choke between the XW10 socket and the upper (according to the transverter circuit) output of the resistor R0,1 100 uH.

Establishing the device is reduced to the selection of capacitor C3 until a stable operation of the relay is obtained.

Author: I.Nechaev (UA3WIA)

See other articles Section Civil radio communications.

Read and write useful comments on this article.

<< Back

<< Back

Latest news of science and technology, new electronics:

A New Way to Control and Manipulate Optical Signals 05.05.2024

The modern world of science and technology is developing rapidly, and every day new methods and technologies appear that open up new prospects for us in various fields. One such innovation is the development by German scientists of a new way to control optical signals, which could lead to significant progress in the field of photonics. Recent research has allowed German scientists to create a tunable waveplate inside a fused silica waveguide. This method, based on the use of a liquid crystal layer, allows one to effectively change the polarization of light passing through a waveguide. This technological breakthrough opens up new prospects for the development of compact and efficient photonic devices capable of processing large volumes of data. The electro-optical control of polarization provided by the new method could provide the basis for a new class of integrated photonic devices. This opens up great opportunities for ... >>

Primium Seneca keyboard 05.05.2024

Keyboards are an integral part of our daily computer work. However, one of the main problems that users face is noise, especially in the case of premium models. But with the new Seneca keyboard from Norbauer & Co, that may change. Seneca is not just a keyboard, it is the result of five years of development work to create the ideal device. Every aspect of this keyboard, from acoustic properties to mechanical characteristics, has been carefully considered and balanced. One of the key features of Seneca is its silent stabilizers, which solve the noise problem common to many keyboards. In addition, the keyboard supports various key widths, making it convenient for any user. Although Seneca is not yet available for purchase, it is scheduled for release in late summer. Norbauer & Co's Seneca represents new standards in keyboard design. Her ... >>

The world's tallest astronomical observatory opened 04.05.2024

Exploring space and its mysteries is a task that attracts the attention of astronomers from all over the world. In the fresh air of the high mountains, far from city light pollution, the stars and planets reveal their secrets with greater clarity. A new page is opening in the history of astronomy with the opening of the world's highest astronomical observatory - the Atacama Observatory of the University of Tokyo. The Atacama Observatory, located at an altitude of 5640 meters above sea level, opens up new opportunities for astronomers in the study of space. This site has become the highest location for a ground-based telescope, providing researchers with a unique tool for studying infrared waves in the Universe. Although the high altitude location provides clearer skies and less interference from the atmosphere, building an observatory on a high mountain poses enormous difficulties and challenges. However, despite the difficulties, the new observatory opens up broad research prospects for astronomers. ... >>

Random news from the Archive Texas Instruments Wireless Ultrasonic Gas Leak Detector 26.09.2019 Texas Instruments presented the development of an ultra-low consumption, self-powered ultrasonic gas leak sensor system with wireless communication with a base station. This reference design is a low power wireless sensor that detects gas leakage by analyzing the ultrasonic spectrum for specific signatures. The system is designed to operate on a single non-rechargeable miniature lithium battery and communicate wirelessly with the base station. This eliminates the need for a wired connection and simplifies installation of the device. The development also uses an ultra-low-power battery level sensor. It is necessary to accurately predict its condition and provide advance notice of the impending end of life for its scheduled replacement. Features: accurate monitoring of the state of the lithium battery, which allows to extend the life of the device and replace the battery in advance; use of multiple power domains to optimize current consumption; system diagnostic mode for accurate estimation of power consumption during development; more than three years of operation when powered by a miniature battery and checking for leakage every 30 seconds; leak detection, regardless of the type of gas (a certain gas concentration is not required to trigger the sensor). Areas of use: gas leak detection; building automation.

Other interesting news:

▪ too good memory

▪ Cheap way to produce nanoparticles

▪ Vaccination against hypertension

▪ Autonomous car turns the driver into an instructor

▪ Monitor ASUS ROG Strix XG43VQ

News feed of science and technology, new electronics

Interesting materials of the Free Technical Library:

▪ section of the site Palindromes. Article selection

▪ article Negative impact of harmful substances on the environment. Fundamentals of safe life

▪ article Which writer suffered from paranoia, which later turned out to be justified? Detailed answer

▪ article Kalgan officinalis. Legends, cultivation, methods of application

▪ article Automotive tachometer. Encyclopedia of radio electronics and electrical engineering

▪ article Miraculous coincidence. Focus Secret

Leave your comment on this article:

All languages ​​of this page

Arabic	Hebrew	Polish
Bengali	Hindi	Portuguese
Chinese	Italian	Spanish
English	Japanese	Turkish
French	Korean	Ukrainian
German	Malay	Vietnamese

Home page | Library | Articles | Website map | Site Reviews

www.diagram.com.ua
2000-2024