Regenerative KB receiver. Scheme, description

Free technical library

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

Regenerative KB receiver. Encyclopedia of radio electronics and electrical engineering

Free technical library

Encyclopedia of radio electronics and electrical engineering / radio reception

Comments on the article

The described 2-V-1 direct amplification receiver is designed to operate in the short wave broadcasting range of 25 m (11,7 ... 12,1 MHz). It was created as an experiment to further study the properties of an autodyne synchronous receiver. Therefore, you can get acquainted with the theoretical part of this problem by reading the article by V. T. Polyakov [1]. The circuit diagram of the receiver is shown in the figure.

(click to enlarge)

The first stage of the high-frequency amplifier is a regenerative Q-multiplier with a high-speed automatic regeneration control system.

The input oscillatory circuit is made up of the inductance of the loop antenna WA1 and the capacitances of the capacitors C6 - C10. Within the specified operating frequencies, it has a very high quality factor, so the effective effective height of the loop antenna can reach several tens of meters. An antenna with such parameters is capable of receiving rather weak signals. The limiting moment on the sensitivity of the receiving device can be the intrinsic noise of the input stage transistor, so it is preferable to use a low-noise transistor in it (the quality factor). In its absence, good results can also be obtained from the widespread and cheap KT315B transistor.

The automatic regeneration control device includes a second stage of a high-frequency amplifier based on a VT2 transistor and a diode detector, consisting of elements C11, VD1, VD2, C13. The initial bias current for silicon diodes and at the same time for the transistor VT1 is created by resistors R1, R2 and R6. The constant component from the output of the detector forms a corrective effect on the regenerative stage, and the variable component through the capacitor C 12 in the form of audio frequency signals is fed to a single-stage audio frequency amplifier based on the VT3 transistor. The load of this amplifier is high-impedance headphones BF1 (for example, TON-2). The output power of the amplifier is about 1 mW.

The stabilization of the modes of transistors VT2 and VT3 is carried out using automatic bias resistors R4 and R9, respectively. It is desirable to choose the resistance value of the resistor R4 so that the voltage at the collector VT2 is close to half the voltage of the power source.

The coil of the WA1 loop antenna is frameless, has an inner diameter of 200 mm, contains two turns of copper wire with a diameter of 1,5 mm, wound with a pitch of 10 mm. For rigidity, the coils are fastened together with inserts made of dielectric material. The coil leads are screwed to the insulating support. If a radio amateur has a 20VCh ferrite rod, you can try to make a ferrite magnetic antenna, but its efficiency will be worse than that of a frame one.

The receiver uses fixed resistors MLT-0,125. Variable resistor R8 type SDR-1, but any other will do. Capacitor C4 oxide of any type, with an operating voltage of at least 6 V. Trimmer capacitor C6 type KPK-M or KPK-1. The variable capacitor C7 can be made independently according to the recommendations of the descriptions in [1, 2] or used with other limits of capacitance change, for example, 4 ... 180 pF, but connect a ceramic capacitor with a capacity of 18 ... 22 pF in series with it. It is also possible to use a varicap as a tuning element, however, this will somewhat reduce the quality factor of the input circuit. In addition, an additional power supply with a voltage of 15 ... 20 V is required to power the varicap. Capacitors C8 - C10 are ceramic KD or KT (any modification and design options). The remaining capacitors are small-sized ceramic of any type. The capacitance of the capacitor C12 is within 0,25 ... 1,0 uF. As a low-noise transistor in the regenerative stage, you can use KT325A, KT368A, KT399A, KT3106A, KT3120A.

The author did not develop a printed circuit board for the experimental version of the receiver, the mounting of the hinged elements on the same insulating stand to which the coil of the loop antenna was attached.

By selecting the capacitor C10 and adjusting the tuning resistor R8, the regenerative stage is stable at the excitation threshold. This is facilitated by the automatic regeneration control system, which monitors the state of the regenerative cascade and applies a corrective action to the base circuit of the transistor VT1 through resistors R6 and R1. Trimmer resistor R8 must be of high quality. Otherwise, the noise of the resistor will interfere with the operation of the receiver. In the absence of a good quality trimming resistor, a fixed resistor should be selected instead. The frequency boundaries of the reception range are set by capacitor C6.

The total current consumed by the receiver is approximately 3 mA, so a fresh 3336L battery is enough for 500 hours of receiver operation.

The proposed version of the receiver well receives signals from distant radio stations and, compared to a simple superheterodyne, provides a cleaner reception due to the narrow-band and directional properties of the loop antenna, the absence of mirror and interference interference. True, these advantages are realized if there are no powerful interfering radio stations.

The disadvantages of the receiver include the deterioration of the parameters of the loop antenna when massive objects approach it and the dependence of the tuning of the regenerative stage on the level of the supply voltage.

Literature

1. Polyakov V. T. Autodyne synchronous receiver. - Radio, 1994, No. 3, p. ten.
2. Borisov V. G. Young radio amateur. Ed. 5th. - M.: Energy, 1972, MRB.

Author: S. Kovalenko, Kstovo, Nizhny Novgorod Region; Publication: N. Bolshakov, rf.atnn.ru

See other articles Section radio reception.

Read and write useful comments on this article.

<< Back

Latest news of science and technology, new electronics:

The existence of an entropy rule for quantum entanglement has been proven 09.05.2024

Quantum mechanics continues to amaze us with its mysterious phenomena and unexpected discoveries. Recently, Bartosz Regula from the RIKEN Center for Quantum Computing and Ludovico Lamy from the University of Amsterdam presented a new discovery that concerns quantum entanglement and its relation to entropy. Quantum entanglement plays an important role in modern quantum information science and technology. However, the complexity of its structure makes understanding and managing it challenging. Regulus and Lamy's discovery shows that quantum entanglement follows an entropy rule similar to that for classical systems. This discovery opens new perspectives in the field of quantum information science and technology, deepening our understanding of quantum entanglement and its connection to thermodynamics. The results of the study indicate the possibility of reversibility of entanglement transformations, which could greatly simplify their use in various quantum technologies. Opening a new rule ... >>

Mini air conditioner Sony Reon Pocket 5 09.05.2024

Summer is a time for relaxation and travel, but often the heat can turn this time into an unbearable torment. Meet a new product from Sony - the Reon Pocket 5 mini-air conditioner, which promises to make summer more comfortable for its users. Sony has introduced a unique device - the Reon Pocket 5 mini-conditioner, which provides body cooling on hot days. With it, users can enjoy coolness anytime, anywhere by simply wearing it around their neck. This mini air conditioner is equipped with automatic adjustment of operating modes, as well as temperature and humidity sensors. Thanks to innovative technologies, Reon Pocket 5 adjusts its operation depending on the user's activity and environmental conditions. Users can easily adjust the temperature using a dedicated mobile app connected via Bluetooth. Additionally, specially designed T-shirts and shorts are available for convenience, to which a mini air conditioner can be attached. The device can oh ... >>

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 ... >>

Random news from the Archive

Two-storey garage in the country 01.04.2003

For those who have two cars, and the summer cottage is so small that there is simply nowhere to put them, Irish designers offer a kind of whatnot.

By pressing a button on the remote control, one car plunges into a concrete pit, and the other is placed on a flat roof that closes this pit.

Other interesting news:

▪ Charging cable Phoenix Contact 375 kW

▪ Shift work increases the risk of depression

▪ RackStation RS3617xs NAS

▪ 18GB SK Hynix LPDDR5 chip

▪ The inhabitants of Pompeii sorted garbage for reuse

News feed of science and technology, new electronics

Interesting materials of the Free Technical Library:

▪ site section Parameters, analogues, marking of radio components. Article selection

▪ Lecoq article. Popular expression

▪ article Is the area of ice caps shrinking at the poles? Detailed answer

▪ article Perennial lettuce. Legends, cultivation, methods of application

▪ article Wound electrical insulating products. Encyclopedia of radio electronics and electrical engineering

▪ article Passive tone control classic simplified. 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