How does a radio receiver work? Setting up the radio receiver. How to set up the radio in a Kia Rio Direct amplification radio with two transistors

You can use a radio to pass the time on the road. Typically, drivers prefer to listen to music that is unobtrusive, so that it plays in the background and does not interfere with steering. An autoradio is most suitable for this, which first needs to be configured. But many people don’t know how to properly set up the radio on their car stereo.

Basically, setting up the radio consists of several simple steps. The broadcast range is selected and radio channels are searched and stored in the tuner’s memory. The search for radio stations occurs either automatically or manual mode. In the first case, radio channels are stored in descending order of broadcast quality.

Let's take a closer look at how to configure the radio on common car radios.

Pioneer

If you are wondering how to set up the radio on your Pioneer radio, don’t worry, setup is very easy. At automatic configuration Pioneer presses FUNC, followed by BSM. To start searching for radio channels, press the right or up button; after finishing, the music of the first radio station found will turn on.

For manual installation In BAND mode, press >>| for a long time. A search will be launched for any first station within this radius. After which the device will stop scanning and start playing the found station. Then you will need to save it; to do this, hold the key with the desired number for a long time. If you do not need the found station, you need to press the right key and hold it. Scanning will continue until a new station is found.

With this function, you can store up to 6 stations in the first bank. After this manipulation, press the BAND button and get into the second bank, it is shown on the display as F2. In the second bank, you can similarly store up to 6 stations in memory, and there is also a third bank. Most often there are three banks, but there are more. As a result, if you have three banks, you will have 18 stations active and saved. Now you know how to set up the radio on your Pioneer radio.

Sony

Setting up the radio in the Sony radio will also not be a problem. Searching for stations is usually carried out in two common ways: manually or automatically. Automatic memorization of radio stations:

1. Turn on the radio. Long press the Source button and wait until TUNER appears on the display.
2. The range is changed by pressing the Mode button. If you press the joystick, a menu of options will appear.
3. Rotate the joystick until the VTM option appears. Radio channels are assigned to numbered keys as standard.

To manually scan and save you need:

1. Turn on the radio and start searching for stations.
2. Once the desired radio station has been found, you need to press the number key from 1 to 6, after which the name “Mem” will appear. Note: when saving a radio station on a digital number that already has a radio station, the previous one is automatically erased.

Thus, you can set up a radio in a Sony radio in 5-10 minutes.

Supra

After pressing the MODE button, select the Radio function, then RADIO and the saved band with the broadcast frequency will be displayed on the screen. Pressing BND selects the desired broadcast band.

Press and hold the >>|| button.

Then click the button >>|| for selection desired station. If these keys are not pressed for up to ten seconds, everything will return to its original operating mode.

Setting in automatic mode and scanning of selected radio stations

Search for existing radio stations in memory:

Briefly press the AS/PS key to start searching for saved radio channels. Any station can be listened to for about a couple of seconds. To automatically save radio channels, hold down the AS/PS key. The receiver will tune in to six optimal stations that are the most powerful in this broadcast range. This option can be applied in any wavelength range. Once the automatic storage of stations is completed, the receiver will stop scanning them.

To tune into a specific radio station, press the >>|| button, this will scan and select radio channels with the best reception signal. By pressing the >>|| button, you can manually select the station you want. Hold down the key numbered 1 to 6 for about a couple of seconds to memorize the channel under the desired key.

J.V.S.

When tuning stations, it is possible to leave 30 FM radio channels and 15 AM channels in the tuner.

Installing stations manually:

1. Select a broadcast band by pressing the TUNER BAND key.
2. Click on button 4 to set the station.
3. Hold down the key with any selected number on the panel to memorize the station in the radio's memory. The selected number will start blinking, after which you will see the station stored under the selected number. For example: To tune to station number 14, press the +10 key, followed by the 4 key for approximately three seconds or more.
4. To store other radio stations in the device’s memory, you need to repeat steps one through three. And to change the settings of the entire station, you need to repeat the entire process from the beginning.

Tuning stations in automatic mode:

Stations will be given numbers by increasing the frequency range.

1. Select the range by pressing the TUNER BAND key.
2. Press and hold the AUTO PRESET button on the panel.
3. To set a different range, you need to go through steps one through two again.

To replace selected stations in automatic mode, you must use manual installation.

Kenwood

Kenwood radios offer three types of autoradio settings: automatic (AUTO), local (LO.S.) and manual.

1. Press SRC until “TUnE” appears.
2. Press FM or AM to select a band.

For automatic setup, click >>| or |.

When manual settings after all the above steps, ST will light up, indicating the found station.

For a long time, radios topped the list of the most significant inventions of mankind. The first such devices have now been reconstructed and changed in a modern way, but little has changed in their assembly circuit - the same antenna, the same grounding and an oscillating circuit for filtering out unnecessary signals. Undoubtedly, circuits have become much more complicated since the time of the creator of radio, Popov. His followers developed transistors and microcircuits to reproduce a higher quality and energy-consuming signal.

Why is it better to start with simple circuits?

If you understand the simple one, you can be sure that most of the path to success in the field of assembly and operation has already been mastered. In this article we will analyze several circuits of such devices, the history of their origin and the main characteristics: frequency, range, etc.

Historical reference

May 7, 1895 is considered the birthday of the radio receiver. On this day, the Russian scientist A.S. Popov demonstrated his apparatus at a meeting of the Russian Physicochemical Society.

In 1899, the first radio communication line, 45 km long, was built between and the city of Kotka. During World War I, direct amplification receivers and vacuum tubes became widespread. During hostilities, the presence of a radio turned out to be strategically necessary.

In 1918, simultaneously in France, Germany and the USA, scientists L. Levvy, L. Schottky and E. Armstrong developed the superheterodyne reception method, but due to weak electron tubes, this principle became widespread only in the 1930s.

Transistor devices emerged and developed in the 50s and 60s. The first widely used radio receiver on four transistors Regency TR-1 was created by German physicist Herbert Mathare with the support of industrialist Jakob Michael. It went on sale in the US in 1954. All old radios used transistors.

Study and implementation began in the 70s integrated circuits. Receivers are now being developed through greater integration of nodes and digital signal processing.

Device characteristics

Both old and modern radios have certain characteristics:

1. Sensitivity is the ability to receive weak signals.
2. Dynamic range - measured in Hertz.
3. Noise immunity.
4. Selectivity (selectivity) - the ability to suppress extraneous signals.
5. Self-noise level.
6. Stability.

These characteristics do not change in new generations of receivers and determine their performance and ease of use.

The principle of operation of radio receivers

In the very general view USSR radio receivers worked according to the following scheme:

1. Due to fluctuations in the electromagnetic field, alternating current appears in the antenna.
2. The oscillations are filtered (selectivity) to separate information from noise, i.e., the important component of the signal is isolated.
3. The received signal is converted into sound (in the case of radio receivers).

Using a similar principle, an image appears on a TV, digital data is transmitted, and radio-controlled equipment (children’s helicopters, cars) operates.

The first receiver was more like a glass tube with two electrodes and sawdust inside. The work was carried out according to the principle of the action of charges on metal powder. The receiver had a huge resistance by modern standards (up to 1000 Ohms) due to the fact that the sawdust had poor contact with each other, and part of the charge slipped into the air space, where it was dissipated. Over time, these filings were replaced by an oscillating circuit and transistors to store and transmit energy.

Depending on the individual receiver circuit, the signal in it may undergo additional amplitude and frequency filtering, amplification, digitization for further software processing, etc. A simple radio receiver circuit provides for single signal processing.

Terminology

An oscillating circuit in its simplest form is a coil and a capacitor closed in a circuit. With their help, you can select the one you need from all the incoming signals due to the circuit’s own frequency of oscillation. USSR radios, as well as modern devices, are based on this segment. How does it all work?

As a rule, radios are powered by batteries, the number of which varies from 1 to 9. For transistor devices, 7D-0.1 and Krona batteries with a voltage of up to 9 V are widely used. The more batteries required simple circuit radio receiver, the longer it will work.

Based on the frequency of received signals, devices are divided into the following types:

1. Long-wave (LW) - from 150 to 450 kHz (easily scattered in the ionosphere). What matters are ground waves, the intensity of which decreases with distance.
2. Medium wave (MV) - from 500 to 1500 kHz (easily scattered in the ionosphere during the day, but reflected at night). During daylight hours, the radius of action is determined by grounded waves, at night - by reflected ones.
3. Shortwave (HF) - from 3 to 30 MHz (do not land, are exclusively reflected by the ionosphere, so there is a radio silence zone around the receiver). With low transmitter power, short waves can travel long distances.
4. Ultrashortwave (UHF) - from 30 to 300 MHz (have a high penetrating ability, are usually reflected by the ionosphere and easily bend around obstacles).
5. - from 300 MHz to 3 GHz (used in cellular communications and Wi-Fi, operate within visual range, do not go around obstacles and propagate in a straight line).
6. Extremely high frequency (EHF) - from 3 to 30 GHz (used for satellite communications, reflected from obstacles and operating within line of sight).
7. Hyper-high frequency (HHF) - from 30 GHz to 300 GHz (they do not bend around obstacles and are reflected like light, they are used extremely limited).

When using HF, MF and DV radio broadcasting can be carried out while being far from the station. The VHF band receives signals more specifically, but if a station only supports it, then you won’t be able to listen on other frequencies. The receiver can be equipped with a player for listening to music, a projector for displaying on remote surfaces, a clock and an alarm clock. The description of the radio receiver circuit with such additions will become more complicated.

The introduction of microcircuits into radio receivers made it possible to significantly increase the reception radius and frequency of signals. Their main advantage is their relatively low energy consumption and small size, which is convenient for portability. The microcircuit contains all the necessary parameters for downsampling the signal and making the output data easier to read. Digital signal processing dominates modern devices. were intended only for transmitting an audio signal, only in recent decades the design of receivers has developed and become more complex.

Circuits of the simplest receivers

The circuit of the simplest radio receiver for assembling a house was developed back in Soviet times. Then, as now, devices were divided into detector, direct amplification, direct conversion, superheterodyne, reflex, regenerative and super-regenerative. Detector receivers are considered the simplest to understand and assemble, from which the development of radio can be considered to have begun at the beginning of the 20th century. The most difficult devices to build were those based on microcircuits and several transistors. However, once you understand one pattern, others will no longer pose a problem.

Simple detector receiver

The circuit of the simplest radio receiver contains two parts: a germanium diode (D8 and D9 are suitable) and a main telephone with high resistance (TON1 or TON2). Since there is no oscillatory circuit in the circuit, it will not be able to catch signals from a specific radio station broadcast in a given area, but it will cope with its main task.

For work you will need good antenna, which can be thrown onto a tree, and a ground wire. To be sure, it is enough to attach it to a massive piece of metal (for example, to a bucket) and bury it a few centimeters into the ground.

Option with oscillating circuit

To introduce selectivity, you can add an inductor and a capacitor to the previous circuit, creating an oscillating circuit. Now, if you wish, you can catch the signal of a specific radio station and even amplify it.

Tube regenerative shortwave receiver

Tube radio receivers, the circuit of which is quite simple, are made to receive signals from amateur stations on short distances- for ranges from VHF (ultra-short wave) to LW (long wave). Finger battery lamps work on this circuit. They generate best on VHF. And the resistance of the anode load is removed by low frequency. All details are shown in the diagram; only the coils and inductor can be considered homemade. If you want to take television signals, then coil L2 (EBF11) is made up of 7 turns with a diameter of 15 mm and a wire of 1.5 mm. 5 turns are suitable.

Direct amplification radio receiver with two transistors

The circuit also contains a two-stage low-frequency amplifier - this is a tunable input oscillatory circuit of the radio receiver. The first stage is an RF modulated signal detector. The inductor coil is wound in 80 turns with PEV-0.25 wire (from the sixth turn there is a tap from below according to the diagram) on a ferrite rod with a diameter of 10 mm and a length of 40.

This simple radio receiver circuit is designed to recognize powerful signals from nearby stations.

Supergenerative device for FM bands

The FM receiver, assembled according to E. Solodovnikov’s model, is easy to assemble, but has high sensitivity (up to 1 µV). Such devices are used for high-frequency signals (more than 1 MHz) with amplitude modulation. Thanks to strong positive feedback, the coefficient increases to infinity, and the circuit goes into generation mode. For this reason, self-excitation occurs. To avoid it and use the receiver as a high-frequency amplifier, set the coefficient level and, when it reaches this value, sharply reduce it to a minimum. For continuous gain monitoring, you can use a sawtooth pulse generator, or you can do it simpler.

In practice, the amplifier itself often acts as a generator. Using filters (R6C7) that highlight low-frequency signals, the passage of ultrasonic vibrations to the input of the subsequent ULF cascade. For FM signals 100-108 MHz, coil L1 is converted into a half-turn with a cross-section of 30 mm and a linear part of 20 mm with a wire diameter of 1 mm. And coil L2 contains 2-3 turns with a diameter of 15 mm and a wire with a cross-section of 0.7 mm inside a half-turn. Receiver amplification is possible for signals from 87.5 MHz.

Device on a chip

The HF radio receiver, whose circuit was developed in the 70s, is now considered the prototype of the Internet. Shortwave signals (3-30 MHz) travel great distances. It is not difficult to set up a receiver to listen to broadcasts in another country. For this, the prototype received the name world radio.

Simple HF receiver

A simpler radio receiver circuit lacks a microcircuit. Covers the range from 4 to 13 MHz in frequency and up to 75 meters in length. Power supply - 9 V from the Krona battery. The installation wire can serve as an antenna. The receiver works with headphones from the player. The high-frequency treatise is built on transistors VT1 and VT2. Due to capacitor C3, a positive reverse charge arises, regulated by resistor R5.

Modern radios

Modern devices are very similar to radio receivers in the USSR: they use the same antenna, which produces weak electromagnetic vibrations. High-frequency vibrations from different radio stations appear in the antenna. They are not used directly to transmit a signal, but carry out the operation of the subsequent circuit. Now this effect is achieved using semiconductor devices.

Receivers were widely developed in the middle of the 20th century and have been continuously improved since then, despite their replacement mobile phones, tablets and TVs.

The general design of radio receivers has changed slightly since Popov's time. We can say that the circuits have become much more complicated, microcircuits and transistors have been added, and it has become possible to receive not only an audio signal, but also to build in a projector. This is how receivers evolved into televisions. Now, if you wish, you can build whatever your heart desires into the device.

Dear visitors!!!

If we compare outdated and modern models of radios, they of course have their differences both in design and in electrical circuits. But the basic principle radio signal reception- not changeable. For modern models radio receivers, only the design itself is changed and minor changes in electrical circuits.

As for tuning the radio receiver to the wave, receiving transmissions in the ranges for:

• long waves\LW\;
• medium waves \NE\,

- usually carried out using a magnetic antenna. In ranges:

— radio sound reception is received via a telescopic \outdoor\ antenna.

Figure 1 shows appearance And graphic designation receiving antennas:

telescopic;

magnetic \antenna DV and SV\.

Reception by magnetic antenna

Figure No. 2 shows a visual representation of how radio waves bend around obstacles \for mountainous areas\. The radio shadow region is represented as a zone beyond the reach of radio waves by the receiver.

What is a magnetic antenna? — The magnetic antenna consists of a ferrite rod, and the magnetic antenna coils are wound on separate \isolated\ frames. The ferrite rod of a magnetic antenna for different radios has its own diameter and length. The winding data of the coils, accordingly, also have their own specific number of turns and their own inductance - for each of these magnetic antenna circuits.

As you understand, such concepts in radio engineering as each individual magnetic antenna circuit And magnetic antenna coil, - have the same meanings, that is, you can formulate your proposal in one way or another.

In radio receivers, a magnetic antenna for DV and SV is mounted in the upper part. In the photograph, the magnetic antenna looks like an oblong, cylindrical rod made of ferrite.

If each coil \circuit\ of a magnetic antenna has its own inductance, then it is designed to receive separate ranges of radio waves. For example, according to electrical diagram radio receiver You observe that the magnetic antenna consists of five separate circuits \L1, L2, L3, L4, L5\, two of which are necessary for the received range:

• DV \L2\;
• NE \L4\.

Other circuits L1 L3 L5 are communication coils, one of which, say L5, is connected to an external antenna. This explanation is not given specifically for each diagram, because the meaning of the designations in the diagrams may change, but it is given general concept about the magnetic antenna.

Reception-on telescopic antenna

telescopic radio antenna

Depending on the radio receiver circuit, the telescopic \whip antenna\ can be connected either to the input circuits of the long and medium wave ranges through a resistor and a coupling coil, or to the input circuits of the short wave range - through an isolating capacitor. From the taps of the coils of the DV, SV or HF circuits, the signal voltage is supplied to the input of the RF amplifier.

Winding data - antennas

The winding on the circuits is made with a single or double wire. Each circuit has its own inductance. The amount of loop inductance is measured in henry. To independently rewind a circuit, you need to know the winding data of this circuit. That is, you need to know:

• number of turns of wire;
• wire section.

All the necessary technical data for outdated models of radios could be found in reference books. On given time, such literature for modern models of radios is not found.

For example, for receivers:

• Mountaineer-405;
• Giala-404,

— the winding data of the coils coincided with each other. That is, let’s say the communication coil \and there are several of them - in the diagram\ with its designation, it could be replaced from one receiver circuit to another circuit.

A circuit malfunction is often associated with mechanical damage wires \accidentally touching a wire with a screwdriver and so on\. When repairing a circuit \rewinding it\, the number of turns of the old wire is usually taken into account and then the same number of turns are performed with a new wire, where its cross-section is also taken into account.

In this article, we have partially gained an understanding of sound reception by a radio receiver. Follow the section, it will be even more interesting.

The high-frequency block contains a converter stage, input and heterodyne circuits. In receivers of the first and highest classes, as well as in the VHF range, there is an amplifier in front of the converter high frequency. Checking and adjusting the high-frequency unit can be divided into three stages: 1) checking local oscillator generation; 2) determining the boundaries of the range, often called range laying; 3) pairing of input and heterodyne circuits.

Laying ranges. The tuning of the receiver to the received station is determined by the tuning of the local oscillator circuits. Input and UHF circuits only increase the sensitivity and selectivity of the receiver. When tuning it to different stations, the local oscillator frequency must always differ from the received frequency by an amount equal to the intermediate one. To ensure constant sensitivity and selectivity over the range, it is desirable that this condition be met at all frequencies in the range. However, this is the frequency ratio across the entire range

is ideal. With one-handed setup, it is difficult to obtain such a pairing. Local oscillator circuits used in broadcast receivers provide precise matching of the settings of the input and local oscillator circuits in each band at only three points. In this case, the deviation from ideal conjugation at other points of the range turns out to be quite acceptable (Fig. 82).

For good sensitivity on the KB range, two precise pairing points are sufficient. The necessary relationships between the frequencies of the input and heterodyne circuits are achieved by complicating the circuit of the latter. The heterodyne circuit, in addition to the usual tuning capacitor C 1 and tuning capacitor C2, includes an additional capacitor SZ, called a mating capacitor (Fig. 83). This capacitor (usually a fixed capacitance with a tolerance of ±5%) is connected in series with a variable capacitor. The inductance of the local oscillator coil is less than the inductance of the input circuit coil.

To correctly determine the boundaries of the range, you must remember the following. The local oscillator frequency at the beginning of each range is mainly affected by a change in the capacitance of the tuning capacitor C 2, and at the end of the range - by a change in the position of the inductor core L and the capacitance of the mating capacitor SZ. The beginning of the range can be considered maximum frequency, to which the receiver can be tuned in this range.

When starting to set up the local oscillator circuits, you should find out the sequence of settings by range. In some receiver circuits, the CB band loop coils are part of the DV band loop coils. In this case, you need to start tuning with medium wave and then tune to long wave.

Most receivers use a band switching scheme that allows each band to be adjusted independently. Therefore, the configuration sequence can be any.

The range is set using the two-point method, the essence of which is to set the limit of the highest frequency (beginning of the range) using a tuning capacitor, and then the lower frequency (end of the range) with the core of the loop coil (Fig. 84). But when setting the limit of the end of the range, the setting of the beginning of the range is somewhat lost. Therefore, you need to check and adjust the beginning of the range again. This operation is performed until both points in the range are in compliance with the scale.

Pairing of input and heterodyne circuits. The setting is made at two points and checked at the third. The exact coupling frequencies in receivers with an intermediate frequency of 465 kHz for the middle of the range (f av) and the ends (f 1 and f 2) can be determined by the formulas:

The circuits are paired at design points, which for standard broadcasting ranges have the following values

IN selected models radio receivers, the pairing frequencies may vary slightly. The lower precision coupling frequency is usually selected 5...10% higher than the minimum frequency of the range, and the upper frequency is 2...5% lower than the maximum. Capacitors with variable capacitance allow you to tune the circuits to exact matching frequencies when turning at angles of 20...30, 65...70 and 135...140°, measured from the position of the minimum capacitance.

To configure tube radio receivers and achieve pairing, the output signal of the generator is connected to the input of the radio receiver (Antenna, Ground sockets) through the all-wave equivalent of the antenna (Fig. 85). Transistor radios that have an internal magnetic antenna are tuned!: using a standard field generator, which is a loop antenna connected to the generator through a non-inductive resistor with a resistance of 80 Ohms.

The decade divider at the end of the generator cable is not connected. The antenna frame is made square with a side of 380 mm from copper wire with a diameter of 4...5 mm. The radio receiver is located at a distance of 1 m from the antenna, and the axis of the ferrite rod should be perpendicular to the plane of the frame (Fig. 86). The magnitude of the field strength in μV/m at a distance of 1 m from the frame is equal to the product of the readings of the generator's smooth and step attenuators.

In the KB band there is no internal magnetic antenna, so the signal from the generator output is fed to the socket external antenna through a capacitor with a capacity of 20...30 pF or to a whip antenna through a decoupling capacitor with a capacity of 6.8...10 pF.

The receiver is tuned on a scale to the highest precise coupling frequency, and the signal generator is adjusted to the maximum voltage at the receiver output. By adjusting the tuning capacitor (trimmer) of the input circuit and gradually reducing the generator voltage, we achieve a maximum increase in the output voltage of the receiver. Thus, pairing is carried out at this point in the range.

Then the receiver and generator are tuned to a lower precise coupling frequency. By rotating the core of the input circuit coil, the maximum voltage is achieved at the output of the receiver. For greater accuracy, this operation is repeated until the maximum voltage at the receiver output is reached. After adjusting the contours at the edges of the range, check the accuracy of the pairing at the middle frequency of the range (third point). To reduce the number of tunings of the generator and receiver, the operations of setting the range and pairing the circuits are often performed simultaneously.

Setting up the LW band. Generator standard signals remains connected to the receiver circuit through an equivalent antenna. The generator is set to a lower frequency range of 160 kHz and an output voltage of 200...500 µV with a modulation depth of 30...50%. The lower coupling frequency is set on the receiver scale (the rotation angle of the KPI rotor is approximately 160...170°).

The gain control is moved to the maximum gain position, and the band control is moved to the narrow band position. Then, by rotating the core of the heterodyne circuit coils, the maximum voltage is achieved at the output of the receiver. Without changing the frequencies of the generator and receiver, the coils of the UHF circuits (if any) and input circuits are adjusted in the same way until the maximum voltage is obtained at the output of the receiver. At the same time, the generator output voltage is gradually reduced.

Having adjusted the end of the DV range, set the variable capacitor to the position corresponding to the coupling point at the highest frequency of the range (KPI rotation angle 20...30°). The generator frequency is set to 400 kHz, and the output voltage to 200...600 µV. By rotating the trimming capacitors of the circuits, first the local oscillator, and then the UHF and input circuits, the maximum output voltage of the receiver is achieved.

Tuning the circuits at the highest frequency of the range changes the tuning to lowest frequency. To increase the accuracy of the settings, the described process must be repeated in the same sequence 2...3 times. When re-adjusting the rotor, the KPI should be placed in the previous position, i.e. in the one in which the first adjustment was carried out. Then you need to check the accuracy of the pairing in the middle of the range. The frequency of the exact pairing in the middle of the LW range is 280 kHz. By setting this frequency on the generator and receiver scale respectively, the calibration accuracy and sensitivity of the receiver are checked. If there is a dip in the sensitivity of the receiver in the middle of the range, then it is necessary to change the capacitance of the coupling capacitor and repeat the tuning process.

The final stage is checking that the settings are correct. To do this, a test stick, which is an insulating rod (or tube), is inserted into the tuned circuit first with one end and then with the other end, with a ferrite rod fixed at one end and a copper rod at the other. If the adjustment is made correctly, then when any end of the test stick is brought to the circuit coil field, the signal at the receiver output should decrease. Otherwise, one end of the stick will reduce the signal, and the other will increase it. After the LW band is configured, you can similarly configure the MW and HF bands. However, as already noted, on the HF band it is enough to pair at two points: at the lower and upper frequencies of the range. In most radio receivers, the KB range is divided into several subbands. In this case, the exact pairing frequencies have the following values!

Features of setting the HF range. When tuning the HF band, the signal from the generator can be heard in two places on the tuning scale. One signal is the main one, and the second is the so-called mirror signal. This is explained by the fact that on the HF band the mirror signal is suppressed much worse, and therefore it can be confused with the Main signal. Let us explain this with an example. A voltage with a frequency of 12,100 kHz is applied to the receiver input, i.e., the beginning of the HF range. In order to obtain a frequency equal to the intermediate frequency at the output of the frequency converter, i.e. 465 kHz, it is necessary to adjust the local oscillator to a frequency equal to 12,565 kHz. When the local oscillator is tuned to a frequency of 465 kHz below the received signal, i.e. 11,635 kHz, an intermediate frequency voltage is also provided at the output of the converter. Thus, the intermediate frequency in the receiver will be obtained at two frequencies, the local oscillator, one of which is higher than the signal frequency by the amount of the intermediate frequency (correct), and the other lower (incorrect). In percentage terms, the difference between the correct and incorrect local oscillator frequencies is very small.

Therefore, when setting the HF range, you should choose from two local oscillator settings the one that is obtained with a lower capacitance of the circuit capacitor or with a more inverted coil core. The correct setting of the local oscillator is checked at a constant frequency of the generator signal. When increasing the capacitance (or inductance) of the local oscillator circuit, the signal should be heard in one more place on the receiver scale. You can also check the correctness of the local oscillator settings while keeping the receiver settings unchanged. When the frequency of the generator signal changes to a frequency equal to two intermediate ones, i.e., 930 kHz, the signal must also be heard. The higher frequency in this case is called the mirror frequency, and the lower frequency signal is the main one.

Setting up the antenna filter. Setting up the high frequency unit begins with setting up the antenna filter. To do this, the output signal of the generator is connected to the input of the receiver through the equivalent of an antenna. On the frequency scale of the generator, a frequency of 465 kHz and a modulation depth of 30...50% are set. The output voltage of the generator must be such that the output meter connected to monitor the output voltage of the receiver shows a voltage of the order of 0.5... 1 V. Receiver range switch set to the DV position, and the tuning pointer to the frequency of 408 kHz. By rotating the core of the antenna filter circuit, achieve a minimum voltage at the receiver output, while increasing the output voltage of the generator as the signal weakens.

After completing the setup, all adjusted cores of the loop coils and the positions of the magnetic antenna coils must be fixed.

Once upon a time there was a Sony radio, when it was sold they said it was Japanese, the price made me believe it, and later I assured everyone that it came from there. Its objective advantage is pure sound. True, there was a small nuance - the FM scale of the 88-108 MHz range, but at the store there was a magician who, for a “small share”, performed a miracle - he filled the scale with many Russian-speaking radio stations. Operated the radio according to full program, but remembering how much was paid for it, they did not throw it or at it. So it was not badly preserved, despite its very advanced age. But the radio broadcasting stations that she caught first diminished, and then there were none left at all.

There is a lot of information on the Internet about setting up sound-reproducing equipment, written competently and in detail. This is a blessing for students of radio engineering universities; they can easily be used instead of notes to prepare for exams, but this information will not help the owner of a sick radio; he is not in the business of increasing his intelligence, but of repairing the receiver. Or throw it away, it’s no longer a shame.

He opened the case and began to disassemble it into its component parts. There are no complaints about either the power supply, which turned out to be super primitive, which is at the bottom left, or the tape drive mechanism of the tape recorder, to the right of it. One produces its 12 V “on the mountain”, and the second regularly pulls the magnetic tape.

And here printed circuit board I wanted to understand a little. To warm up, I checked all electrolytic capacitors for the actual presence of capacity and ESR. It's hard to believe, but everyone turned out to be completely fine. I unsoldered and disassembled the volume control - a variable resistor, for example, for revision. Once upon a time, a long time ago, he acted a little badly and was, through a medical syringe with a needle, awarded a portion of machine oil. Does it need a supplement? And there was so much oil in it that I could just put it on the frying pan, blot off the excess, and return it to its place. I washed the board on the side of the printed conductors with formic alcohol specially purchased at the pharmacy (they didn’t give anything else), and then, so that there was no white residue left from it, with hot water and shampoo. It turned out not bad, although this method is perceived by ear as a bit wild.

The wire contacts going to the speaker have been soldered. And around the circumference of the speaker I installed a rim - a flexible tube cut lengthwise from a medical dropper. This is so that the metal of the speaker does not rest on the plastic of the housing - it will definitely not worsen the sound characteristics.

And then, very opportunely, I remembered that the master who was modifying the radio tape recorder spoke about some kind of wire spirals. There were several of them on the board, all in the area of ​​the variable capacitor. Partially assembled the device, turned it on, and at the desired range began to touch the copper wires wound in rings with a screwdriver. Two did not respond, and as soon as I touched the third, characteristic sound changes appeared in the dynamics. Found! Bottom one in the photo. I touched it well with tweezers, but it was dangling. I desoldered it, straightened it and wound it again, on a mandrel of a suitable diameter. Soldered it in place. The FM band came to life. At this point I finally got bolder and let’s move the coils with a screwdriver (increase and decrease the gap between them). In response to my actions, the location and number of stations on the scale began to change. But the most convenient for setting were two tweezers. He stretched and squeezed them like an accordion, only gently. See this action clearly in the video.

Video

As a result, I chose the combination of stations that suited me and had the optimal location on the scale. The only difficulty is to do everything slowly, otherwise, you know, you want everything faster. Good luck! The simplest option for a possible restoration repair - settings - was shared by Babay iz Barnaula.