Transceiver YES-97 2. Scheme, description

Free technical library

ENCYCLOPEDIA OF RADIO ELECTRONICS AND ELECTRICAL ENGINEERING
Free library / Schemes of radio-electronic and electrical devices

Transceiver YES-97 (continued). Encyclopedia of radio electronics and electrical engineering

Free technical library

Encyclopedia of radio electronics and electrical engineering / Civil radio communications

Comments on the article

Having previously considered the main components of the YES-97 transceiver, we kind of left one of its most important components, the GPA, "overboard". Therefore, in an effort to correct this oversight, we present its schematic diagram and a brief description of the work. I especially want to emphasize that the transceiver's GPA is universal, the output parameters are stored in a wide range of generated frequencies, and it can certainly be used in similar amateur radio designs. In this case, frequency overlaps by ranges are determined and set independently, RW3AY.GPA - smooth range generator

The GPA transceiver favorably differs from known similar units primarily by high frequency stability, a wide range of overlapping frequencies and a highly stable output signal amplitude. The frequency generator is assembled on field-effect transistors that implement the function of a lambda diode. The normal mode of operation is supported by a thermo-independent voltage regulator assembled on a K 140UD6 microcircuit. The ranges are switched by relay switches, which provide the connection of loop capacitors, both stretching capacitors and setting the boundaries of the ranges.

The generated voltage passes through the buffer stage on the KP303A transistor and through the driver on the K555LAZ chip, which also branches the GPA signal. The "RX detuning" mode is provided by two KB 131 varicaps. They also perform additional stabilization of the GPA by a digital locked loop (DAFC) circuit. Schematic diagram of the GPA transceiver "YES-97" is shown in Fig.1. Coil L1 in the frequency generator is special, a suitable coil made of high quality radio porcelain with cast copper is used. It is known that the stability of the GPA frequency depends on the quality of its manufacture.

Setting up the GPA is a very painstaking job, and it begins with setting a constant voltage on the lambda diode of about 2,7 V (K140D6, pin 6). Then the AC voltage on the L1 circuit is checked over the entire frequency range from 5 to 21 MHz. Its maximum value is about 2 V. Band trim capacitors are made up of several capacitors with different TKEs to provide the necessary long-term frequency stability without a connected DAC. If necessary, elements marked with asterisks (*) are selected.

(click to enlarge)

Surge Suppressor - PIP

An impulse noise suppressor (PIP) can be proposed for installation in radio receivers with double frequency conversion. The operation of the PIP is based on the frequency shift of the second local oscillator. If sufficiently narrow-band filters are installed in the path of the first and second IF receivers, then changing the frequency of the second local oscillator by several kilohertz to the side will lead to the fact that the signal and interference will no longer fall into the passband of the second filter. The PIP is based on the scheme published in the Radio magazine No. 9-98 on pp. 24-27. In the same article, the principles and methods of dealing with impulse noise are well described, so it makes no sense to repeat them here. I will dwell only on the introduction of PIP into the radio receiver path. Schematic diagram of the PIP transceiver "YES-97" is shown in Fig.2. Realizing that there is no "universal" receiver, and there may be differences in its construction - with one or more frequency conversions, I will give a way to connect a PIP to a receiver with a low intermediate frequency of 500 kHz.

From the output of the 2nd mixer of the radio receiver (500 kHz), the interference signal, together with the received signal, is fed to the input of a cascode amplifier based on transistors KP350B and KT368A, amplified, and then detected by a pulse detector on the GD507. The detected signal comes to the input of the K544SAZ comparator. The comparator threshold is set by a 68 kΩ variable resistor. At the output of the comparator, rectangular pulses are generated corresponding to interference pulses that are fed to the delay circuit assembled on the K561LE5 microcircuit. The delay time corresponds to the transit time of the interference signal from the 2nd to the 3rd mixer. Usually, this time may vary (depending on the actual receiver circuit), but does not exceed 1-10 ms. The delay time is selected by a 4,7 kΩ resistor. After its expiration, a rectangular pulse is formed, corresponding to the duration of the interference pulse. With a 68 kΩ variable resistor, the duration of this pulse can be adjusted from 2 to 50 ms, it is desirable to control its shape and duration with an oscilloscope.

The control pulse that appears opens the KT342 transistor, which closes the KV131 varicap bias circuit to the case, which leads to an abrupt (5-6 kHz) decrease in the frequency of the reference oscillator assembled on the K561LA7 chip. The 8367 kHz sinusoidal signal from the output of the reference frequency generator is fed to the receiver's SSB/CW mixing detector, sometimes referred to as the third mixer. The operation of the PIP leads to the attenuation of the interference signal by more than 80 dB, without tangible switching interference.

The PIP is tuned by ear, but it is desirable to control the shape and duration of the pulses using an oscilloscope. For more thorough tuning, it is advisable to use some kind of pulse generator with adjustable frequency and duty cycle of the output signal. The more precise the setting, the better it works. A variable resistor of 68 kΩ is used to finalize the turn-off time of the receiving path. It should be taken into account that it should not exceed 10% of the time of the interference pulse, otherwise there will be a temporary loss of the useful signal. The PIP node is placed on a small printed circuit board made of 2-sided fiberglass, placed in a metal shielding case. Coils L1 and L2 (in a cascade amplifier) can be taken from the 465 kHz IF of any transistor broadcast receiver.

(click to enlarge)

Author: G.Bragin, RZ4HK Chapaevsk; Publication: N. Bolshakov, rf.atnn.ru

See other articles Section Civil radio communications.

Read and write useful comments on this article.

<< Back

Latest news of science and technology, new electronics:

Machine for thinning flowers in gardens 02.05.2024

In modern agriculture, technological progress is developing aimed at increasing the efficiency of plant care processes. The innovative Florix flower thinning machine was presented in Italy, designed to optimize the harvesting stage. This tool is equipped with mobile arms, allowing it to be easily adapted to the needs of the garden. The operator can adjust the speed of the thin wires by controlling them from the tractor cab using a joystick. This approach significantly increases the efficiency of the flower thinning process, providing the possibility of individual adjustment to the specific conditions of the garden, as well as the variety and type of fruit grown in it. After testing the Florix machine for two years on various types of fruit, the results were very encouraging. Farmers such as Filiberto Montanari, who has used a Florix machine for several years, have reported a significant reduction in the time and labor required to thin flowers. ... >>

Advanced Infrared Microscope 02.05.2024

Microscopes play an important role in scientific research, allowing scientists to delve into structures and processes invisible to the eye. However, various microscopy methods have their limitations, and among them was the limitation of resolution when using the infrared range. But the latest achievements of Japanese researchers from the University of Tokyo open up new prospects for studying the microworld. Scientists from the University of Tokyo have unveiled a new microscope that will revolutionize the capabilities of infrared microscopy. This advanced instrument allows you to see the internal structures of living bacteria with amazing clarity on the nanometer scale. Typically, mid-infrared microscopes are limited by low resolution, but the latest development from Japanese researchers overcomes these limitations. According to scientists, the developed microscope allows creating images with a resolution of up to 120 nanometers, which is 30 times higher than the resolution of traditional microscopes. ... >>

Air trap for insects 01.05.2024

Agriculture is one of the key sectors of the economy, and pest control is an integral part of this process. A team of scientists from the Indian Council of Agricultural Research-Central Potato Research Institute (ICAR-CPRI), Shimla, has come up with an innovative solution to this problem - a wind-powered insect air trap. This device addresses the shortcomings of traditional pest control methods by providing real-time insect population data. The trap is powered entirely by wind energy, making it an environmentally friendly solution that requires no power. Its unique design allows monitoring of both harmful and beneficial insects, providing a complete overview of the population in any agricultural area. “By assessing target pests at the right time, we can take necessary measures to control both pests and diseases,” says Kapil ... >>

Random news from the Archive

Tomatoes and apples treat the lungs of smokers 01.01.2018

Scientists from the Johns Hopkins Bloomberg School of Public Health have shown that the lungs of smokers recover more easily after quitting a bad habit if quitters eat a lot of apples and tomatoes.

Lung function declined more slowly in ex-smokers the more tomatoes and fruits, especially apples, in their diet. The difference is made by at least two tomatoes and more than three fresh fruits a day. The researchers also looked at the effects of canned and cooked vegetables and fruits (including ketchup), but found that they did not have a noticeable effect on lung health. Even in people who never smoked, apples and tomatoes slowed the age-related decline in lung function.

Since 2002, 680 residents of three European countries have taken part in the study (the average age of the study participants was 43 years); all of them answered the questions of the questionnaire and underwent the procedure of spirometric measurement of lung volume and respiratory rate with an interval of ten years. Consumption of different foodstuffs was assessed by appropriate questionnaires.

Scientists attribute the effect to the antioxidants found in fruits and tomatoes; in small amounts, they do not have a significant effect on the body, but long-term dietary intake of antioxidants leads to a significant slowdown in the development of abnormal lung function with age and even reverses the negative effects of smoking in ex-smokers. The authors of the study note that their results should be taken into account by therapists who give dietary advice to smokers.

Other interesting news:

▪ WD Blue SN550 2TB NVMe SSD

▪ Climate change has affected the taste of coffee

▪ Samurai brushing their teeth

▪ Digital wallet instead of paper and plastic documents

▪ CIA in the fight against global warming

News feed of science and technology, new electronics

Interesting materials of the Free Technical Library:

▪ site section Chargers, accumulators, batteries. Article selection

▪ article Life is short, art is eternal. Popular expression

▪ article Who wrote the black square a quarter of a century before Malevich? Detailed answer

▪ article Field radish. Legends, cultivation, methods of application

▪ article Soft start and stop of the electric motor. Encyclopedia of radio electronics and electrical engineering

▪ article Obedient ball. physical experiment

Leave your comment on this article:

All languages of this page

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