Parametric converter. Encyclopedia of radio electronics and electrical engineering
Encyclopedia of radio electronics and electrical engineering / Knots of amateur radio equipment. Mixers, frequency converters
Comments on the article
In modern HF communication receivers, an intermediate frequency of tens of megahertz is often used (the so-called "up conversion"). The advantage of such receivers is a very high selectivity for the image channel and the possibility of a simple circuit implementation of smooth tuning over the entire range of received short waves. In this case, it is often possible to simplify the input circuits by implementing them in the form of a low-pass filter with a cutoff frequency of 30 MHz.
To obtain the greatest signal amplification per KB, it is desirable to choose a higher value of the intermediate frequency, but at the same time, the intermediate frequency should be convenient for subsequent amplification and conversion. In amateur conditions, the most convenient frequency is 144 MHz. It lies well above the upper limit of the KB range, and amateur VHF receivers can be used for further signal processing.
Ris.1
A schematic diagram of a parametric amplifier-converter for obtaining a high intermediate frequency is shown in fig. 1. It is made according to the balanced scheme on two varicaps VI and V2. Equal in amplitude and opposite in phase, the pump voltage to the varicaps comes from the secondary winding of the transformer T1, which has a grounded tap from the midpoint. The required initial mixing voltage on the varicaps is created using a divider across resistors R1, R4, R5, R6. Trimmer resistor R5 balances the converter.
The input signal is fed through the coupling coil L2 to the L3C7 circuit, tuned to a frequency of 7 MHz. This circuit is connected to the anodes of the varicaps through a decoupling capacitor C5 and a choke L1. The output circuit L4C8, tuned to an intermediate frequency of 144 MHz, is connected to the anodes of the diodes through a small capacitor Sat. The frequency converter has a high stability of characteristics both when the mixing voltage and the pump power change. For example, when the supply voltage is reduced from 12 to 6 V, the gain drops by only 1 dB, and a decrease in the amplitude of the pump voltage (in each section of the secondary winding of the T1 transformer from 1.5 V to 1,0 V) leads to a decrease in gain by only 3 dB.
For the most complete use of the capabilities of this frequency converter amplifier, it is required to use a VHF receiver with a UHF gain of 30 ... 40 dB and providing effective linear filtering of the conversion products.
The parameters of the converter amplifier can be improved by introducing a balancing transformer into the pump circuit (see Fig. 2). All three transformers are identical here.
Ris.2
In the described amplifier-converter, D901A or D901B varicaps can be used.
Literature
- "Electron". Netherlands, November 1981
Publication: N. Bolshakov, rf.atnn.ru
See other articles Section Knots of amateur radio equipment. Mixers, frequency converters.
Read and write useful comments on this article.
<< Back
Latest news of science and technology, new electronics:
Energy from space for Starship
08.05.2024
Producing solar energy in space is becoming more feasible with the advent of new technologies and the development of space programs. The head of the startup Virtus Solis shared his vision of using SpaceX's Starship to create orbital power plants capable of powering the Earth. Startup Virtus Solis has unveiled an ambitious project to create orbital power plants using SpaceX's Starship. This idea could significantly change the field of solar energy production, making it more accessible and cheaper. The core of the startup's plan is to reduce the cost of launching satellites into space using Starship. This technological breakthrough is expected to make solar energy production in space more competitive with traditional energy sources. Virtual Solis plans to build large photovoltaic panels in orbit, using Starship to deliver the necessary equipment. However, one of the key challenges ... >>
New method for creating powerful batteries
08.05.2024
With the development of technology and the expanding use of electronics, the issue of creating efficient and safe energy sources is becoming increasingly urgent. Researchers at the University of Queensland have unveiled a new approach to creating high-power zinc-based batteries that could change the landscape of the energy industry. One of the main problems with traditional water-based rechargeable batteries was their low voltage, which limited their use in modern devices. But thanks to a new method developed by scientists, this drawback has been successfully overcome. As part of their research, scientists turned to a special organic compound - catechol. It turned out to be an important component that can improve battery stability and increase its efficiency. This approach has led to a significant increase in the voltage of zinc-ion batteries, making them more competitive. According to scientists, such batteries have several advantages. They have b ... >>
Alcohol content of warm beer
07.05.2024
Beer, as one of the most common alcoholic drinks, has its own unique taste, which can change depending on the temperature of consumption. A new study by an international team of scientists has found that beer temperature has a significant impact on the perception of alcoholic taste. The study, led by materials scientist Lei Jiang, found that at different temperatures, ethanol and water molecules form different types of clusters, which affects the perception of alcoholic taste. At low temperatures, more pyramid-like clusters form, which reduces the pungency of the "ethanol" taste and makes the drink taste less alcoholic. On the contrary, as the temperature increases, the clusters become more chain-like, resulting in a more pronounced alcoholic taste. This explains why the taste of some alcoholic drinks, such as baijiu, can change depending on temperature. The data obtained opens up new prospects for beverage manufacturers, ... >>
| Random news from the Archive Noise can raise blood cholesterol levels
02.06.2018
American scientists called noise in the workplace a serious factor in developing hypertension, as well as an increase in blood cholesterol levels. They studied the impact of noise on people employed in industrial production.
Approximately one in eight of those working in this field reported hearing problems. It turned out that more than 50% of them faced health problems over time precisely because of exposure to excessive noise in the workplace.
"Approximately a quarter of all workers were exposed to loud noise in the workplace. 24% were found to have hypertension. 28% of participants showed too high cholesterol levels," the researchers said.
According to scientists, the most dangerous, based on the above parameters, are production, construction and mining. At least half of the people working in these industries are systematically exposed to loud noise.
|
Other interesting news:
▪ Neurostimulation helps with chronic pain
▪ Mobile chip Wi-Gig
▪ Android 5.0 is expected in the second quarter of 2012.
▪ Garbage t-shirts
▪ Death Rays vs Drones
News feed of science and technology, new electronics
Interesting materials of the Free Technical Library:
▪ section of the site Dosimeters. Selection of articles
▪ article Toy boat with a jet engine. Tips for a modeler
▪ article What fabulous role did Georgy Millyar play almost without make-up? Detailed answer
▪ article Kotovnik Transcaucasian. Legends, cultivation, methods of application
▪ See Parallel Phone Call. Encyclopedia of radio electronics and electrical engineering
▪ article Magician's tables. Focus Secret
Leave your comment on this article:
All languages of this page
Home page | Library | Articles | Website map | Site Reviews
www.diagram.com.ua
2000-2024
Arabic
Bengali
Chinese
English
French
German
Hebrew
Hindi
Italian
Japanese
Korean
Malay
Polish
Portuguese
Spanish
Turkish
Ukrainian
Vietnamese