Instructions on how to tune a radio on a radio tape recorder from various manufacturers. How to tune the radio in Kia Rio Installing the radio

Once upon a time there was a Sony radio tape recorder, at the sale they said that it was Japanese, the price made me believe, later he assured everyone that she was from there. Its objective merit is pure sound. True, there was a small nuance - the scale of the FM range of 88-108 MHz, but at the store there was a magician who, for a "small fraction", created a miracle - he filled the scale with many Russian-speaking radio stations. They exploited the radio tape recorder in full, 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 respectable age. That's just the broadcasting stations that she caught, at first diminished, and then there were no more.

There is a sea of \u200b\u200binformation on the Internet regarding the setting of sound-reproducing equipment, it is written competently, in detail. This is happiness for students of radio engineering universities, you can easily use it instead of notes to prepare for exams, and this infa will not help the owner of a radioactive radio, it's not to improve his intellect, but to fix the receiver. Or throw it away, it's no longer a pity.

I opened the case, began to disassemble it into its component parts. There are no complaints about the power supply unit, 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 gives out its 12 V "to the mountain", and the second regularly pulls the magnetic tape.

But the printed circuit board wanted to understand a little. For 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 in perfect order. I soldered and disassembled the volume control - a variable resistor, for example, a revision. Somehow a long time ago he got a little runny and was, through a syringe with a needle, awarded a portion of machine oil. Does it need a supplement? And there was so much oil in it that even now I blotted the excess in the pan, put it back in place. I washed the board from the side of the printed conductors with formic alcohol specially bought at the pharmacy (they did not give anything else), and then, so that there was no white coating from it, with hot water and shampoo. It turned out not bad, although it is perceived by ear, this method is wild.

The contacts of the wires, suitable for the speaker, are soldered. And around the circumference of the speaker I installed a rim - a flexible tube cut along the length from a medical dropper. This is to prevent the metal of the speaker from resting on the plastic of the case - it will definitely not be worse for the sound characteristics.

And then, very by the way, I remembered that the master who was finalizing the radio tape recorder was talking about some kind of wire spirals. There were several of them on the board and all in the area of \u200b\u200bthe variable capacitor. I partially assembled the device, turned it on and, at the desired range, began to touch the copper wires wound with rings with a screwdriver. Two did not respond, but barely touched the third, characteristic changes in sound appeared in the dynamics. Found! In the photo below. I touched it well with tweezers, but it dangles. Soldered, straightened and rewound, on a mandrel of a suitable diameter. Soldered in place. The FM band came to life. Then I became completely bold and let's move the turns 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. You can clearly see this action in the video.

Video

As a result, I chose a combination of stations suitable for myself and optimal in terms of location on the scale. The difficulty is only in doing everything slowly, otherwise, you know, you want everything faster. Good luck! The simplest option for a possible refurbishment is the settings shared by Babay iz Barnaula.

Each radio has settings for a certain frequency, most of them even have fixed ones, which is very convenient. If the receiver is digital, that is, it has an electronic setting, then fixing a particular radio station on a specific channel will not be difficult. This process will be a little more difficult on receivers with a conventional tuning scale. But, in any case, the user manual describes in detail how to tune the radio receiver and how many stations you can store in its memory. However, all this can be done only after purchasing this very radio receiver. Many people face the problem of choice these days, because there are a lot of all kinds of models in stores.

For those who want to listen to all radio stations, an all-wave receiver will be the best option. And if he has the opportunity to receive VHF waves, then it will be just happiness, because such receivers can also catch conversations over the radio. Therefore, it is worth thinking about how to choose a radio receiver, for what purposes it will be used and what should it be? If it is a "cabinet" receiver, then the standard FM and AM bands will be enough for it. For "portable" and "travel" receivers, it is better to be able to "listen" to all frequencies, since treks can also be in unfamiliar areas, where radio can broadcast on any frequency. "Portable" ones can just play around and eavesdrop on other people's conversations if they use walkie-talkies.

If you cannot buy such a receiver, then you should think about how to assemble a radio receiver so that it can “hear” in the required range. To do this, you need to be a radio amateur, or have one of them in very close friends. You can, of course, rummage on the Internet and search step by step instructions for assembling the radio. But there are also pitfalls, because not all the necessary parts can be bought, some have to be done by yourself. Therefore, if you have a friend who is a radio amateur, then you can ask him how the radio works, what parts can you buy, and which and how you need to do it yourself, and most importantly from what? After the answers to the questions are received, you can start looking for the necessary parts, both for the receiver and parts for parts for your radio.

You will have to run around the shops a lot, look in the pantry old technique and dig deeper into it in search of the necessary parts. After that, you will have to spend a lot of time with a soldering iron in your hands and use up a few grams of tin and wires. And now, when all the details are ready, you will have to contact a friend with the question of how to make a radio receiver so that it works reliably and for a long time. What the radio will be like doesn't really matter. Both the homemade and commercial receiver receive radio waves. If he brings pleasure to his master, then he will fulfill his destiny.

So, observing reasonable care, we open the device. We look at what the frequency control knob is connected to. It can be a variometer (a metal, several centimeters gizmo, usually two or one double, with longitudinal holes into which a pair of cores slide in or out.) This option has often been used before. Until I write about it. () And it may be a plastic cube a few centimeters in size (2 ... 3). Several capacitors live in it, which change their capacity at our whim. (There is also a method of tuning with varicaps. In this case, the tuning control is very similar to the volume control. I have never seen such an option).

2. LET'S FIND A HETERODOUS COIL AND CONDENSERS CONNECTED TO IT.

So, you have KPE! We proceed further. We are looking for copper coils around it (yellow, brown spirals of several turns. Usually they are not even, but crumpled and knocked down. And this is correct, they are tuned this way.). We can see one, two, three or more coils. Don't be alarmed. Everything is very simple. We turn on your device in disassembled form (do not forget to connect the antenna longer) and tune it to any radio station (better not to the loudest). After that, touch it with a metal screwdriver or just with your finger (contact is not necessary, just slide something near the coil. The receiver will react differently. The signal may become louder or there may be interference, but the coil we are looking for will give the strongest effect. several stations and the reception will be completely disrupted. So this is what a HETERODY coil. The frequency of the local oscillator is determined by a circuit consisting of this very coil and capacitors connected in parallel to it. There are several of them - one of them is in the CPE and controls the frequency tuning (we catch with it different stations), the second is also located in the KPE cube, or rather on its surface. Two or four small screws on the rear surface of the KPE (usually it is facing us) are two or four trimming capacitors. One of them is used to adjust the local oscillator. Usually these capacitors consist of two plates that slide over each other when the screw rotates. the lower plate is exactly above the lower one, then capacity is maximum ... Use a screwdriver to touch these screws. Move them back and forth a few (as little) degrees as possible. You can mark their starting position with a marker to insure against trouble. Which one affects the setting? Found it? We will need it in the near future.

3. Once again, LET'S DETERMINE WHERE WE ARE REBUILDING AND ACTING.

What range is in your receiver and what you need. Lowering the frequency or raising it? To lower the frequency, it is enough to add 1 ... 2 turns to the heterodyne coil. As a rule, it contains 5 ... 10 turns. Take a piece of bare tinned wire (for example, a lead from some long-legged element) and put on a small prosthesis. After this build-up, the coil must be adjusted. We turn on the receiver and catch some station. No stations? Nonsense, let's take a longer antenna and turn the tuning. Here, something is caught. What is it. We'll have to wait until they say or take another receiver and catch the same thing. See how this station is located. Whether at the end of the range. Need to move it even lower? Easily. Let's move the coil turns more tightly. Let's catch this station again. Good now? It only catches badly (the antenna needs a long one). Correctly. Now let's find the antenna coil. She is somewhere near. The wires from the KPI must be suitable for it. Let's try turning on the receiver, insert it into it, or simply bring some ferrite core to it (you can take the DM choke by removing the winding from it). Has the volume increased? Exactly, this is it. To reduce the frequency, it is necessary to increase the coil by 2 ... 3 turns. A piece of hard copper wire will do. You can simply replace the old coils with new ones containing 20% \u200b\u200bmore turns. The turns of these coils should not be tight. By changing the stretching of the coil and bending it, we change the inductance. The tighter the coil is wound and the more turns in it, the higher its inductance and below will be the working range. Do not forget that the actual inductance of the loop is higher than the inductance of a single coil, since it is added to the inductance of the conductors that make up the loop.

For the best reception of the radio signal, it is necessary that the difference in the resonant frequencies of the heterodyne and antenna circuits is 10.7 MHz - this is the frequency of the intermediate frequency filter. This is called correct pairing of the input and heterodyne circuits. How to provide it? We read on.

SETTING (PAIRING) INPUT AND HETERODY CIRCUITS.

FIG. 1. High-frequency part of the VHF-FM radio receiver board. It is clearly seen that the input circuit trimmer (CA-P) is set to the minimum capacitance position (as opposed to the CG-P heterodyne trimmer). Accuracy of setting the rotors of the trimmer capacitors is 10 degrees.

The local oscillator (LG) coil has a large hole in the winding that reduces its inductance. This hole appeared during the setup process.

Another coil is visible at the top of the photo. This is the input antenna circuit. It is broadband and not tunable. The telescopic antenna is connected to this very circuit (via a transition capacitor). The purpose of this circuit is to remove coarse interference at frequencies well below the operating ones.

AND ANOTHER ACTION, BECAUSE WE ARE ALREADY HERE.

Tune in to your favorite station, then shorten the antenna to a minimum when there is already interference and adjust the IF filter, which looks like a metal square with a purple circle (in the middle left of the photo). Fine tuning this circuit is very important for clear and loud reception. Accuracy of slot installation is 10 degrees.

Setting up a transistor receiver, in principle, differs little from setting up a tube receiver. After making sure that the bass amplifier is corrected and the tubes or transistors of the receiver are working in normal modes, they begin to adjust the circuits. The tuning begins with the detector stage, then proceeds to the IF amplifier, local oscillator and input circuits.

The best way to tune outlines is with a generator high frequency... If it is not there, then you can tune in by ear, according to the received radio stations. In this case, it may be necessary to only have an avometer of any type (TT-1, VK7-1) and another receiver, the intermediate frequency of which is equal to the intermediate frequency of the tuned receiver, but sometimes it is tuned without any instruments. The autometer serves as an indicator of the output signal during setup.

When tuning the IF amplifier circuits in a tube receiver, when an RF generator and a tube voltmeter are used for this purpose, the latter must not be connected to the lamp grid, since the input capacitance of the voltmeter is added to the capacitance of the grid circuit. When adjusting the circuits, a voltmeter should be connected to the anode of the next lamp. In this case, the circuit in the anode circuit of this lamp must be shunted with a resistor with a resistance of about 500 - 1000 Ohm.

Having finished setting up the IF gain path, proceed to setting up the local oscillator and the RF amplifier. If the receiver has several bands, then the tuning begins with the KB band, and then proceeds to tuning.

Circuits of CB and LW ranges. Short-wave coils (and sometimes medium-wave ones), unlike long-wave ones, usually do not have cores; they are wound most often on cylindrical (and sometimes on ribbed) frames. The change in the inductance of such coils is performed when tuning the circuits, shifting or moving apart the turns of the coils.

In order to determine whether the turns should be shifted or moved apart in a given circuit, it is necessary to bring inside the coil or bring a piece of ferrite and a brass (or copper) rod alternately to it. It is even more convenient to perform this operation if, instead of a separate piece of ferrite and a brass rod, use a special combined indicator stick, at one end of which magnetite (ferrite) is fixed, and at the other end - a brass rod.

The inductance of the coil of the RF amplifier circuit should be increased if, at the mating points of the circuits, the volume of the signal at the output of the receiver increases when ferrite is introduced into the coil and decreases when a brass rod is introduced, and vice versa, the inductance should be reduced if the volume increases when a brass rod is introduced and decreases with the introduction of ferrite. If the circuit is configured correctly, the attenuation of the signal volume at the mating points occurs when both ferrite and brass rods are inserted.

The CB and LW contours are tuned in the same order. The change in the inductance of the coil of the loop at the mating points is made in these ranges by the corresponding adjustment of the ferrite core.

When making homemade loop coils, it is recommended to wind a few obviously extra turns. If, when tuning the circuits, it turns out that the inductance of the loop coil is insufficient, winding up the turns on the finished coil will be much more difficult than winding up the extra turns during the tuning itself.

The factory receiver can be used to make it easier to set up contours and graduate the scale. Comparing the angles of rotation of the axes of the variable capacitors of the tuned receiver and the factory receiver (if the blocks are the same) or the position of the scale pointers, they determine in which direction the loop setting should be shifted. If the station on the scale of the tuned receiver is closer to the beginning of the scale than the factory one, then the capacity of the tuning capacitor of the local oscillator circuit should be reduced, and vice versa, if closer to the middle of the scale, it should be increased.

Methods for checking the local oscillator in a tube receiver. You can check if the local oscillator is working in the tube receiver. different ways: Using a voltmeter, optical tuning indicator, etc.

When using a voltmeter, it is connected in parallel with a resistor in the anode circuit of the local oscillator. If the short circuit of the capacitor plates in the local oscillator circuit causes an increase in the voltmeter readings, then the local oscillator works. The voltmeter must have a resistance of at least 1000 Ohm / V and be set to a measurement limit of 100 - 150 V.

Checking the operability of the local oscillator with an optical tuning indicator (6E5C lamp) is also not difficult. To do this, the control grid of the local oscillator lamp is connected with a short conductor to the grid of the 6E5C lamp through a resistor with a resistance of 0.5-2 MΩ. The dark sector of the tuning indicator should be completely closed during normal operation of the local oscillator. By the change in the dark sector of the 6E5C lamp when you rotate the receiver tuning knob, you can judge about the change in the generator voltage amplitude in different parts of the range. If the unevenness of the amplitude is observed within significant limits, a more uniform generation over the range can be achieved by selecting the number of turns of the coupling coil.

The operation of the local oscillator of the transistor receiver is checked by measuring the voltage at the load of the local oscillator (most often at the emitter of the transistor of a frequency converter or mixer). The local oscillator voltage, at which the frequency conversion is most effective, lies in the range of 80 - 150 mV on all ranges. The voltage across the load is measured with a lamp voltmeter (VZ-2A, VZ-3, etc.). When the local oscillator circuit is closed, its oscillations break down, which can be noted by measuring the voltage across its load.

Sometimes self-excitation can be eliminated very in simple ways... So, in order to eliminate self-excitation in the IF amplification stage, a 100 - 150 Ohm resistor can be included in the control grid of the lamp of this stage. The amplification of the intermediate frequency voltage in the stage will decrease slightly, since only a small part of the input signal voltage is lost on the resistance.

In transistor receivers, self-excitation can be observed if the battery of cells or accumulators is discharged. In this case, the battery should be replaced and the batteries charged.

In some cases, self-excitation in the receiver and TV can be eliminated by such measures as transferring the grounding of individual circuit elements, reworking the installation, etc. The effectiveness of the measures taken to combat self-excitation can often be assessed in the following way.

Figure: 25. To an explanation of the way to eliminate self-excitation in transistor reflex receivers

The receiver or TV set is connected to a regulated power source (that is, to a source whose voltage supplied to the anode circuits can be varied over a wide range), and a lamp voltmeter or other dial indicator is turned on at the output of the receiver. Since at the moment of self-excitation the voltage at the output of the receiver changes sharply, the deviation of the indicator arrow makes it easy to note this. The voltage taken from the source is controlled by a voltmeter.

If self-excitation occurs at the rated voltage, then the supply voltage is reduced to a value at which generation stops. Then they take certain measures against self-excitation and increase the voltage until generation occurs, marking it with a voltmeter. In the case of successful measures taken, the self-excitation threshold should increase significantly.

In transistor reflex receivers, self-excitation can occur due to the unfortunate location of the high-frequency transformer (or choke) relative to the magnetic antenna. Such self-excitation can be eliminated by using a short-circuited turn of a copper wire with a diameter of 0.6 - 1.0 mm (Fig. 25). A U-shaped wire bracket is passed through a hole in the board, bent from below, twisted and soldered to the common wire of the receiver. The bracket can serve as a fastening element for the transformer. If the transformer winding is evenly wound on the ferrite ring, then the appropriate orientation of the short-circuited turn relative to other ferrite parts is not required.

Why does the receiver "howl" on the KB band. It can often be observed that a superheterodyne receiver, when receiving a broadcasting station at short wavelengths, starts to "howl" with a small detuning. However, if the receiver is tuned more precisely to the station being received, reception will return to normal.

The reason for the “howling” when the receiver is operating at short wavelengths is the acoustic coupling between the receiver loudspeaker and the tuning capacitor bank.

This generation can be eliminated by improving the damping of the tuner, as well as reducing the various available methods of acoustic feedback - changing the way the loudspeaker is mounted, etc.

Tuning the IF amplifier with another receiver. At the beginning of this section, a method was described for tuning a radio receiver using the simplest devices. In the absence of such devices, the tuning of radio receivers is usually performed by ear, without devices. However, it should be said right away that this method does not provide sufficient tuning accuracy and can be used only as a last resort.

To tune the IF amplifier loops, instead of a standard signal generator, you can use another receiver with an IF equal to the IF of the receiver being tuned. -With a tuned tube receiver, the AGC wire going from the diode to the control grids of the adjustable lamps must be disconnected from the diode during tuning and connected to the chassis. If this is not done, then the AGC system will make it difficult to fine-tune the bandpass filters. In addition, when tuning the IF amplifier, it is necessary to disrupt the oscillations of the local oscillator by blocking its circuit with a capacitor with a capacity of 0.25 - 0.5 μF.

The auxiliary receiver used in this case does not need to undergo any significant alterations. To set up, you need only a few additional parts: a variable resistor (0.5 - 1 MΩ), two constant capacitors and two or three constant resistance resistors.

Tuning the amplifier circuits. IF of the receiver is produced as follows. The auxiliary receiver is pre-tuned to one of the local long- or medium-wave stations. Further, the common wires or the chassis of both receivers are connected to each other, and the wire going in the tube receiver to the control grid of the lamp of the first IF gain stage of the auxiliary receiver is disconnected and connected to the control grid of the lamp of the corresponding IF amplifier stage of the tunable receiver. In the case of tuning a transistor receiver, the IF signal through capacitors with a capacity of 500 - 1000 pF is fed alternately to the bases of the transistors of the corresponding stages of the IF amplifier.

Then both receivers turn on again, however, in order to avoid interference when tuning, the low-frequency part of the auxiliary, as well as the local oscillator of the tuned receiver, should be turned off (in tube receivers, removing the lamps of the LF amplifier and local oscillator, respectively).

When tuning the cascades of the IF amplifier of a transistor receiver, its local oscillator should be turned off by installing a jumper in the local oscillator circuit.

After that, by applying the intermediate frequency signal from the auxiliary receiver to the input of the tunable IF amplifier and smoothly adjusting the tuning of the IF circuits of the latter, they achieve the audibility of the station to which the auxiliary receiver is tuned. Then they continue to tune each circuit separately (to the maximum signal level), and the tuning is best done using a dial gauge connected to the output of the bass amplifier, or by an optical indicator (6E5C lamp or the like).

Start tuning from the last IF loop; the signal is fed to the base of the corresponding transistor or directly to the grid of the lamp, in the anode circuit of which the tunable circuit is included.

If the adjustment is carried out not by an optical indicator, but by the volume of the sound, then the volume level is recommended to be set to the minimum, since the human ear is more sensitive to changes in the volume level in weak sounds.

About tuning the receiver to radio stations. Tuning of a superheterodyne receiver - tube or transistor - for received stations without using an auxiliary receiver is usually started on the KB band. By adjusting the IF contours to the maximum of noise and turning the tuning knob, the receiver is installed on any of the audible stations. If it is possible to receive such a station, then they immediately begin to adjust the IF circuits, achieving maximum audibility (the tuning starts from the last IF circuit). Then they tune the heterodyne and input circuits, first on short, then on medium and long waves. It should be noted that setting up receivers using this method is difficult, time consuming and requires experience and skills.

The 6E5C lamp is an indicator when setting up. As already mentioned, it is not recommended to adjust the receiver contours in terms of sound volume, especially if a high output volume level is set. The sensitivity of the human ear to changes in signal level during loud sounds is very low. Therefore, if you still have to tune the receiver by sound, then you should set the volume control to a low level, or, what is better, use an optical tuning indicator - a 6E5C lamp or another similar one.

When tuning superheterodyne receivers according to received stations and using the 6E5C lamp as an indicator of tuning accuracy, it is more convenient to adjust the contours at such an input signal level at which the dark sector of this lamp narrows to 1 - 2 mm.

To regulate the signal voltage at the input of the receiver, parallel to the antenna coil, you can connect, for example, a variable resistance resistor, the value of which, depending on the sensitivity of the receiver, can be selected in the range from 2 to 10 kOhm.

How to find a faulty stage in an RF amplifier. When establishing or repairing a receiver, a cascade in which there is a malfunction can be detected with the help of an antenna, alternately connecting it to the bases of transistors or to the grids of amplifier lamps and determining by ear by noise whether there are malfunctions in these cascades.

This method is convenient to use in cases where there are several RF amplification stages.

An antenna in the form of a piece of wire can also be used when checking the IF and RF amplification cascades in TVs. Since short-wave stations often work at frequencies close to the intermediate frequency of televisions, listening to these stations will indicate the health of the audio channel,