Simple Q-meter. Encyclopedia of radio electronics and electrical engineering
Encyclopedia of radio electronics and electrical engineering / Measuring technology
Comments on the article
In the manufacture of communication KB equipment, it often becomes necessary to measure the quality factor and inductance of coils (usually in the range from units to several tens of microhenries). If your receiver or transceiver has an S-meter, then a simple prefix will allow you to use it to determine the inductance. And if the S-meter is sufficiently accurately calibrated, then, using its readings, one can also evaluate the quality factor of the coil.
The attachment diagram is shown in the figure. The prefix consists of an oscillator with quartz frequency stabilization and a measuring circuit. The generation frequency, of course, is chosen within one of the amateur ranges. In this case, a quartz resonator was used at a frequency of 3579 kHz (from the color blocks of NTSC TVs).
In the general case, the exact value of the frequency is not significant - it only affects the conversion factor in the formula for calculating the inductance. For the above frequency, this formula has the form:
L = 1974 / C,
where L is the inductance of the coil under study (μH), C is the capacitance of the measuring circuit (nF).
At the bottom of the circuit, the "capacitive three-point" capacitor is divided into two connected in series (C5 and C6). A small signal is taken from the capacitor C6. The large capacitance of this capacitor virtually eliminates its influence on the parameters of the measuring circuit. This capacitor must be of high quality, in particular, have a low TKE.
The signal from the generator is fed to a series oscillatory circuit formed by an inductor, the parameters of which must be measured, and capacitors C7 - C10. To expand the measurement limits, switch S1 can connect the second section of the variable capacitor, and switch S2 - a capacitor with a capacity close to the maximum for one section of the KPI. This combination allows you to get capacitance coverage from the minimum (for one section of the variable capacitor) to three times the maximum value of the capacitance of this section.
Capacitors C9 and C10 form a divider that attenuates the output signal to a level that is acceptable to the receiver.
At the specified frequency and ratings, the capacitor C7 - C10. using the attachment, you can measure the inductance of the coils in the range from 1,5 to 80 μH. In the original article, the measurement limits are given as 2...40 µH, but in practice they are wider.
During measurements, the receiver is tuned to the frequency of the generator and by adjusting the capacitor C7, the maximum readings of the S-meter are achieved. If necessary (if there is no signal maximum within the capacitance change of one section of the variable capacitor C7), its second section is connected, and if this is not enough, then the capacitor C8. The receiver gain control knobs for radio and intermediate frequencies select the required signal level (so that the S-meter does not go off scale). Before measurements, the scale of a variable capacitor must be calibrated using coils with a known inductance. There should actually be three scales: for one KPI section. for two sections and for two sections plus a permanent capacitor.
In the general case, it is not at all necessary to use an oscillator with quartz frequency stabilization in such a device. The short-term stability of a conventional LC oscillator may well be enough to determine the parameters of a single inductor, so the Z01 resonator can be replaced with a coil with an inductance of about 78 uH.
Transistor VT1 can be any high-frequency silicon npn structure (KT315 series, etc.).
Literature
- Enkel Q-meter for 2 - 40uH. - QTC. 1992. No. 7, p.8
- KV magazine 1/92
Publication: N. Bolshakov, rf.atnn.ru
See other articles Section Measuring technology.
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 Ion Engine X-3
20.10.2017
NASA specialists tested the X-3 ion engine developed by researchers from the University of Michigan (USA), which set new records for power, thrust and current.
The principle of operation of the X-3 engine is based on the Hall effect, which occurs when a magnetic field acts on moving charged particles - for example, gas ions. In this case, the ions deviate from their trajectory, which causes a current perpendicular to the main direction. This creates additional thrust and makes it possible to achieve a high flow rate of xenon, which is used as an ionized gas.
The ion thruster, one meter in diameter, weighs 227 kilograms and is equipped with three plasma output channels, which makes it possible to reduce its size compared to single-channel thrusters. The X-3 is powered by the XR-100 electric propulsion system developed by the American company Aerojet Rocketdyne. During the process in the vacuum chamber, the engine showed a power of more than 100 kilowatts and a thrust of 5,4 newtons.
For comparison, other samples of Hall effect ion thrusters developed a power of no more than five kilowatts. The main advantage of such engines is a high specific impulse - about 40 kilometers per second. Conventional liquid fuel rockets develop only 5 kilometers per second. As a result, less fuel is spent, but the thrust is low, so ion engines have not yet been able to overcome the earth's gravity.
NASA specialists intend to continue testing the X-3 ion engine next year. During the next stage of testing, scientists are going to test the endurance of the engine by making it run at full power for 100 hours. Especially for this experiment, a special magnetic shielding system will be built, which will protect the walls of the ion engine from hot plasma.
|
Other interesting news:
▪ Microscopic 3D printer from IBM
▪ Stretching the diamond
▪ SpaceX to launch ASFPC-52 military satellite
▪ The world may go coal-free
▪ Demand for LCD panels is on the rise
News feed of science and technology, new electronics
Interesting materials of the Free Technical Library:
▪ section of the site Winged words, phraseological units. Selection of articles
▪ article Behavioral strategy and methods of protection in the conditions of local wars and regional armed conflicts. Fundamentals of safe life
▪ article Does an ostrich really hide its head in the sand in case of danger? Detailed answer
▪ article Bicycle on skis. Personal transport
▪ article Automatic shutdown of radio equipment. Encyclopedia of radio electronics and electrical engineering
▪ article Your first receiver. Encyclopedia of radio electronics and electrical engineering
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