Stable RF generator. Scheme, description

Free technical library

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

Stable RF generator. Encyclopedia of radio electronics and electrical engineering

Free technical library

Encyclopedia of radio electronics and electrical engineering / Knots of amateur radio equipment. Generators, heterodynes

Comments on the article

The proposed generator operates in the frequency range from 26560 kHz to 27620 kHz and is designed to tune SV equipment. The signal voltage from "Out 1" is 0,05 V into a 50 ohm load. There is also "Output 2". to which you can connect a frequency meter when setting up receivers. The generator provides the possibility of obtaining frequency-modulated oscillations. For this, the "Input mod." is used, to which a low-frequency signal is supplied from an external audio frequency generator. The generator is powered from a stabilized source of +12 V. The current consumed does not exceed 20 mA. The master oscillator is made on field-effect transistors VT1. VT2. connected according to the "common source - common gate" scheme.

(click to enlarge)

The generator, assembled according to this scheme, works well at frequencies from 1 to 100 MHz. because it uses field-effect transistors with a cutoff frequency >100 MHz. According to the research [1]. this generator has a short-term frequency instability (for 10 s) better than generators made according to capacitive and inductive three-point circuits. The frequency drift of the generator for every 30 minutes of operation after a two-hour warm-up, as well as the levels of the second and third harmonics, is less than for generators made according to the three-point scheme. Positive feedback in the generator is carried out by capacitor C10. An oscillating circuit C1 ... C5 is included in the gate circuit VT8. L1. which determines the frequency of circuit generation.

A varicap matrix VD9 is connected to the circuit through a small capacitance C1. By applying a low-frequency signal to it, we change its capacitance and thereby carry out frequency modulation of the generator. The generator power supply is additionally stabilized by VD2. The high-frequency signal is taken from the resistor R6. included in the source circuits of the transistors. A broadband emitter follower on VT11 and VT3 is connected to the generator through capacitor C 4. The advantages of such a repeater are given in [2]. A voltage divider (R15.R14) is connected to its output through a capacitor C 15. The output impedance for "Output 1" is 50 ohms. therefore, using a coaxial cable with a wave impedance of 50 ohms, you can connect a circuit with an input impedance of 50 ohms to it. for example, the RF attenuator published in [3]. A source follower on VT5 is connected to the output of the emitter follower. This made it possible to completely eliminate the mutual influence of loads. connected to "Out.1" and "Out.2".

Details. Capacitors C6 ... C10 - type KT6. Other capacitors: ceramic - type K10-7V. K10-17. electrolytic - type K50-35. Coil L1 is wound on a ceramic ribbed frame (the size of the ribs is 15 mm) with a silver-plated wire with a diameter of 1 mm with a pitch of 2 mm. The number of turns is 6.75. The winding is carried out with a heated wire with "pressure". Inductor L2 - from black and white tube TVs (others can be used) with an inductance from 100 to 300 μH. Resistors - type MLT-0.125. Field-effect transistors can be applied to any of the KP303 series. even better - from the KP307 series. High-frequency connectors Х1...ХЗ - type СР50-73ФВ. Transistor VT3 - any high-frequency npn-type. VT4 - high frequency pnp type.

Setting. In some instances of field-effect transistors, parasitic relaxation and intermittent high-frequency generation are possible. In this case, the selection of resistor R6 and capacitor C10 is required. To obtain the minimum value of the temperature coefficient of frequency, it is necessary to select capacitors C6 ... C8 with both positive and negative TKE, taking into account the conclusions. made in the article [4]. The generator must be placed in a shielded case made of brass or foil fiberglass. This high-frequency generator has only one switching point when switching bands, so it is easy to perform on several bands. The calculation of the oscillatory circuit for other ranges can be performed according to the method. given in [5].

Literature

1. Kotienko D.. Turkin N. LC generator on field-effect transistors. - Radio. 1990. No. 5. p.59.
2. Broadband voltage follower. - Radio. 1981. No. 4. p.61.
3. RF attenuator. - Radio amateur. KB and VHF. 1996. No. 10. p.36.
4. Mukhin V. Non-standard behavior of inductors when heated. - Radio amateur. 1996. No. 9. p.13. 14.
5. Maslov E. Calculation of an oscillatory circuit for stretched tuning. - Radio amateur, 1995. No. 6. With. 14-16.

Author: O. Belousov, Ukraine, Cherkasy region, Vatutyno; Publication: N. Bolshakov, rf.atnn.ru

See other articles Section Knots of amateur radio equipment. Generators, heterodynes.

Read and write useful comments on this article.

<< Back

Latest news of science and technology, new electronics:

Artificial leather for touch emulation 15.04.2024

In a modern technology world where distance is becoming increasingly commonplace, maintaining connection and a sense of closeness is important. Recent developments in artificial skin by German scientists from Saarland University represent a new era in virtual interactions. German researchers from Saarland University have developed ultra-thin films that can transmit the sensation of touch over a distance. This cutting-edge technology provides new opportunities for virtual communication, especially for those who find themselves far from their loved ones. The ultra-thin films developed by the researchers, just 50 micrometers thick, can be integrated into textiles and worn like a second skin. These films act as sensors that recognize tactile signals from mom or dad, and as actuators that transmit these movements to the baby. Parents' touch to the fabric activates sensors that react to pressure and deform the ultra-thin film. This ... >>

Petgugu Global cat litter 15.04.2024

Taking care of pets can often be a challenge, especially when it comes to keeping your home clean. A new interesting solution from the Petgugu Global startup has been presented, which will make life easier for cat owners and help them keep their home perfectly clean and tidy. Startup Petgugu Global has unveiled a unique cat toilet that can automatically flush feces, keeping your home clean and fresh. This innovative device is equipped with various smart sensors that monitor your pet's toilet activity and activate to automatically clean after use. The device connects to the sewer system and ensures efficient waste removal without the need for intervention from the owner. Additionally, the toilet has a large flushable storage capacity, making it ideal for multi-cat households. The Petgugu cat litter bowl is designed for use with water-soluble litters and offers a range of additional ... >>

The attractiveness of caring men 14.04.2024

The stereotype that women prefer "bad boys" has long been widespread. However, recent research conducted by British scientists from Monash University offers a new perspective on this issue. They looked at how women responded to men's emotional responsibility and willingness to help others. The study's findings could change our understanding of what makes men attractive to women. A study conducted by scientists from Monash University leads to new findings about men's attractiveness to women. In the experiment, women were shown photographs of men with brief stories about their behavior in various situations, including their reaction to an encounter with a homeless person. Some of the men ignored the homeless man, while others helped him, such as buying him food. A study found that men who showed empathy and kindness were more attractive to women compared to men who showed empathy and kindness. ... >>

Random news from the Archive

Turbine from the other side of the world 01.07.2004

In 2009, the Three Gorges power plant on the Yangtze River (China) is to be put into operation.

The reservoir, the creation of which had to relocate almost two million people from 13 cities, 116 towns and about 4500 villages, is larger in area than Switzerland. For the first stage of the power plant, eight turbines were ordered in France, three of them will be delivered from there, and five were built by French specialists at a plant in China.

The first of three turbines has just arrived on site. The turbine plant is located in Grenoble, and the cargo was supposed to be sent from the port of Marseille. However, since not all bridges on the road from Grenoble to Marseille could withstand a load with a diameter of 11 meters and a weight of 450 tons, the turbine was delivered to Marseille in parts and assembled there. For this, an assembly shop was built on the shores of the Mediterranean Sea.

Having sailed 20 kilometers on a ship to Shanghai, the turbine was loaded onto a barge and followed the river almost to the very dam. The last 30 kilometers had to be overcome by land, on a cargo platform with 288 wheels.

Other interesting news:

▪ Speed sensor VG481V1

▪ Lamppost of the XNUMXst century

▪ solar stop

▪ Created the highest quality laser

▪ HyperCharger X Wireless Charging Mobile Battery

News feed of science and technology, new electronics

Interesting materials of the Free Technical Library:

▪ site section Measuring equipment. Article selection

▪ article by Edward Everett. Famous aphorisms

▪ article Why is the center of the Earth hot? Detailed answer

▪ article Telecom operator. Standard instruction on labor protection

▪ article Stamping of iron and steel. Simple recipes and tips

▪ article Powerful transistor in avalanche mode. 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