Um welcome. Simple AM ​​receiver (circuit diagram based on IC ZN415)

SIMPLE RADIO RECEIVERS ON TDA1072 CHIP

Above is a diagram of a radio receiver for the long and medium wave ranges with a ferrite antenna on a rod 15-20 cm long, using the IF and demodulation circuits of the TDA1072 microcircuit. The device can be used to receive local and national stations on medium and long waves, respectively.

The radio receiver shown in Fig. 13.2 is a variant of the previous one, but in it the field-effect transistor acts on the antenna circuit as a negative resistance (Q multiplier). Important characteristics such as gain and selectivity are relatively small, since you have to make do with a ferrite rod 5-8 cm long.

SIMPLE RECEIVER FOR TELEGRAPHY 35-140 KHZ

The field effect transistor in this circuit is used as a demodulator and a beat oscillator. Demodulation of amplitude-modulated oscillations is possible when a signal is applied to a receiver located on the border of self-excitation (figure on the right). To receive signals in other ranges, the number of antenna turns is determined inversely proportional to the minimum frequency. It may be necessary to change elements C 3 and R1 to maintain sufficient vibration amplitude.

DIRECT GAIN RECEIVER WITH AUTOMATIC SELECTIVITY

Rice. 13.4

The voltage assigned to the setting indicator increases the collector current of transistor T 3 in proportion to the amplitude of the received signal. This reduces the current available for transistors T1 and T2. As a result, bandwidth and reception convenience increase with increasing input signal level.

LONG WAVE RECEIVER with audible INTERMEDIATE FREQUENCY

This receiver operates with an intermediate frequency of 2.5 kHz, which falls within the audible range. It is possible to achieve lower frequencies by changing the antenna coil, the number of turns of which should be inversely proportional to the frequency. To adjust the correspondence between the antenna current and the local oscillator, it is necessary to limit the range width with capacitor C 7. By changing the location of the winding on the ferrite rod, the lower limit of the frequency range is achieved, and using the tuning capacitor C1, the upper limit is achieved.

Improved tuning matching of series capacitor C s. For capacitor C 6 10/500 pF and the range 34-152 kHz – L reT = 40.1 µH, C s = 5600 pF, for the range 39-155 kHz – L reT = – 30.2 µH, C s = 6600 pF , for the range 12-40 kHz – L reT = 276 μH, C s = 2200 pF (Fig. 13.5b).

Tuning the antenna circuit with a varicap is carried out by applying a voltage of 0-8 V to it (Fig. 13.5c).

To tune the local oscillator with a varicap, the capacitance of the capacitor C s is taken exactly the same as in Fig. 13.5b. In addition, it is necessary to stabilize the power supply so that during telegraphy a buzzing sound does not appear when the output amplifier discharges the battery (Fig. 13.5d).

SUPER REGENERATIVE RECEIVER 80-125 MHz

This device can receive signals with amplitude and frequency modulation. Insufficient elimination of the regenerated frequency by the output filter interferes only with a high level of gain by the output stage.

Note Unear Technologie, dans Electronlque, Paris, December 1998, p. 80 Fig. 13.6

SUPER REGENERATIVE 27 MHz RECEIVER

Transistor T1 interferes with the radiation of oscillations of the receiver's local oscillator by the antenna. Antenna and input capacitance of transistor T1 together

Le Haut-Parleur, Paris, No. 1619, p. 49-53 Fig. 13.7

Le Haut-Parleur, Paris, No. 1619, p. 49-53 Fig. 13.8

with the inductance of the L1 coils provide tuning to the middle of the frequency band. The regeneration frequency of self-oscillations (10-20 kHz) is eliminated by an active filter having a gain of 20. The degree of feedback is selected by a variable resistor P so as to ensure the most favorable reception. External source of regeneration, shown in Fig. 13.8, significantly improves the selectivity and sensitivity of the receiver. Interference from this source of sine or triangular oscillations in the audio channel is very well removed by an LC filter with a ferrite core. For the coils, frames with a diameter of 8 mm with tuning cores are used. Inductor L1 contains 20 turns located at a length of 15 mm, coil L 2 - 2 turns of the primary winding and 15 turns of the secondary. The wire for L1 has a diameter of 0.4 mm, for L 2 - 0.1 mm. Coil L 3 consists of 40-50 turns.

DIRECT SHORT WAVE AMPLIFIER RECEIVERS

Funkamateur; Berlin, No. 3/99, p. 279-281 Fig. 13.9

Transistor T1 is a potential generator, which, without bringing it to self-excitation, must be adjusted with a variable resistor P1. With a drain current of only 10 μA, the detection result is quite satisfactory.

In Fig. Figure 13.10 shows a variant of the previous circuit with separation of circuits for excitation (T1, T2) and detection. The magnetic antenna consists of 5 turns of wire with a diameter of 3.5 mm, the distance between the turns is 6.5 mm, the winding diameter is 10 cm. The receiver covers the range of 4.7-18 MHz. If oscillations appear at the beginning of the P2 stroke, it is recommended to increase the resistance of resistors R1 and P1.

SHORT WAVE PRESELECTOR WITH SYMMETRICAL UHF

funkamateur, Berlin, No. 5/97, p. 554 Fig. 13.11

The device shown in the diagram works well at high input signal levels due to the symmetrical input of the amplifier, which compensates for the nonlinearity of the transistor characteristics. The gain of the device is about 3. A coreless loop coil, wound on a frame with a diameter of 22 mm for the 4.7-19 MHz range, contains 9.5 turns of wire with a diameter of 0.8 mm with a distance between turns of 1.2 mm. The coupling coil with the antenna is located at a distance of 5 mm from the grounded end of the loop coil and, depending on the length of the antenna, contains from one to four turns of wire with a diameter of 0.5 mm; the distance between the turns is 1 mm.

AM RECEIVER ON LM1863 CHIP

The sensitivity of the receiver shown in Fig. 13.12, is 2.2 µV. The “stop” function affects the frequency synthesizer and serves to automatically search for stations. Pins 13 and 8 are not connected to the circuit.

RECEIVER ON AN7002K CHIP

The device, the diagram of which is shown in Fig. 13.13, is intended for receiving radio transmissions in the long and medium wave ranges. Output power is 120 mW into an 8 ohm load. Nominal signal voltage at the demodulator output is 24 mV eff. Sensitivity is no less than 4.5 dBµV.

AM RECEIVER ON CA3088 CHIP

The receiver assembled according to Fig. 13.14, contains two stages of the amplifier and an analog multiplier for demodulation, as well as a local oscillator connected to a resonant circuit, which is located in front of the converter stage. RF pre-amplification must be provided to prevent the antenna from emitting local oscillator oscillations.

Note d'application no. 381, National Semiconductors Fig. 13. 12

Documentation Panasonic

This device is designed to receive digital signals. The bandwidth is 20 kHz – 1 MHz.

The ZN415 microcircuit is a complete path of a direct amplification radio broadcast receiver for working with amplitude modulation, including a radio frequency amplifier, a detector, and a low-frequency amplifier for working with headphones. Rated supply voltage 1.5V.

Samarin A.P.

The ZN415 microcircuit is an upgrade of the ZN414 microcircuit, which is executed in a three-pin “transistor” package, but differs from it in the presence of a telephone ULF, and is made in a DIP-8 package.

The ZN415 microcircuit can be used as the basis of a direct amplification receiver, or as an intermediate frequency path and telephone ULF of a simple superheterodyne AM receiver.

The figure shows a diagram of a direct amplification AM receiver operating in a range covering the mid-wave range and the high-frequency part of the long-wave broadcasting range.

Reception is carried out using a magnetic antenna consisting of a ferrite rod and coil L1. The input of the URCH microcircuit is relatively high-impedance, so a coupling coil or tap is not required and the input circuit, consisting of L1 and a variable capacitor C1, is connected to the input of the URCH (pin 1) directly (without taps or coupling coils).

The magnetic antenna consists of a ferrite rod with a diameter of 8 mm and a length as long as the receiver body allows. Coil L1 is wound on a homemade frame. It is a sleeve glued together from whatman paper or thick paper.

Coil L1 contains 75 turns of PEV 0.43 or other wire, with a diameter of 0.3 to 0.6 mm. Winding - turn to turn. First fix the ends of the winding with threads, rubber rings or electrical tape; during the installation process you may have to select the number of turns so that all powerful local radio stations operating on both medium and long waves are included in the tuning range.

Variable capacitor C1 - from a superheterodyne receiver. It has two sections for AM ranges of 7-270 pF. They are connected in parallel, so the result is 14-540 pf. You can use a capacitor of another capacity, for example, 5-240 pF (if connected in parallel it will be 10-480 pF).

The output of the detector is pin 2. Through capacitor C4, the signal is supplied to the telephone ULF. Phones are connected to pin 5 via a standard connector (female-plug).

Stereo phones are used for listening; their common output is not connected anywhere, so the headphones are connected in series. You can use standard stereo mini-headphones or a single mono telephone. Power source - one galvanic cell of type “AAA” with a voltage of 1.5V.

AM radio receivers are designed to receive amplitude-modulated signals with a frequency typically not exceeding 30 MHz.

Previously were widespread because, with maximum simplicity, the products made it possible to receive information in the ranges of long, medium and short radio waves. In subsequent years, due to the development of high-frequency ranges and other communication principles that ensure high-quality transmission of audio signals, such devices fell out of use and are mainly of interest in terms of studying the theory and practice of radio communications.

Downtime can be done on just one chip. The diagram is shown in the figure below (click to enlarge).

The MK484 microcircuit (Rapid Electronics Ltd) contains a built-in input emitter follower providing an input resistance of up to 4 MOhm, a high-frequency amplifier, a detector and an automatic gain control system (10 transistors in total).

To operate in the mid-wave range, coil L1 must have an inductance of 470 µH. To do this, it is wound on a ferrite rod with a diameter of 10 mm with a magnetic permeability of 600-1000. The winding contains approximately 80 turns of enameled wire with a diameter of 0.2 mm, the winding length is 50 mm.

The input circuits of a radio receiver may contain resonant tuning elements to the frequency of the received radio station, Fig. 1, or receive non-selectively all signals arriving at the device input in the frequency range 0.15-3 MHz, Fig. 2. The microcircuit can also work as part of superheterodyne radio receivers. With a supply voltage of 1.1-1.8 V, it consumes current up to 0.3 mA. Gain - 70 dB with nonlinear distortion coefficient up to 4%. Audio frequency output voltage is 5-30 mV.

A full-fledged analogue of the MK484 microcircuit is the VT7084 microcircuit, which is connected according to an identical standard circuit [Fig. 2.] as well as Z484, SY484, TA7642, UTC7642, D7642 [Fig. 3].

The most simplified version of the radio receiver on the MK484 microcircuit, powered by one finger-type element, is shown in Fig. 3. The load of the radio receiver is headphones with a resistance of 32-500 Ohms. When using high-resistance phones, resistor R2 can be excluded from the circuit, or replaced with a potentiometer, turning it into a volume control. The telephone, or more precisely, the connector that connects it, also serves as a switch for the device. The receiver consumes current up to 300 μA from a power source with a voltage of 1.25-1.5 V.

When a radio amateur has a question about which broadcast radio receiver is better: a traditional one with a mechanical scale or a modern one with a digital scale, domestically produced or imported, the answer is usually very ambiguous and primarily depends on the level of the radio amateur’s needs and his experience. For a novice amateur, a domestically produced “receiver” or an imported radio tape recorder is sufficient, but for cool DX players, give us special domestically produced communication receivers (also called “military”, because we didn’t make such receivers for the people) or imported digital portables and semi-professional ones desktop receivers.

Unfortunately, the production of domestic radio receiving equipment, both for mass use and suitable for DXing, is currently practically non-existent. “Average” DXists, at best, can count on old stocks of “Ishimovs” with a digital scale, and “cool” ones - on pound P-250s or “Katrans” and similar rough-looking coherent “coffins”, which nevertheless have decent radio receiving characteristics in comparison even with vaunted imported digital equipment. There should be no doubt: if the area of ​​your apartment allows, you are unpretentious and your family is not disturbed by the noise of the mechanisms of domestic “coffins”, plus you have a living wage in your pocket - buy it when the opportunity arises without hesitation. Although the reliability is less, at least the maintainability and modifiability of our devices is unrivaled, and they can be purchased at a significantly lower cost than the corresponding categories of imported ones.

There is another, cheaper, but much more painful way - to make the receiver yourself from “saved” parts and scrap materials (some simpler, some more complex). For example, for DXing for almost 20 years now I have been successfully using a homemade radio receiving setup with double conversion in the range from 100 kHz to 30 MHz, with a bunch of amateur “bells and whistles” such as a first local oscillator synthesizer with silent frequency switching in 1 MHz variable steps capacity, digital scale (frequency meter), three IF filters (FSS and two EMF), a notch filter at a frequency of 5 kHz, two types of local oscillators for SSB reception, a low-frequency amplifier and almost all of this on the chassis and in the wooden case of an old tube receiver using for the second IF of the redesigned Meridian board and for the UHF ranges DV and SV - the old pocket receiver "Kiev-7" In general, the need for invention is cunning :-).

But, however, modern imported radio receiving industry offers a significantly greater variety of types of receivers for all categories of radio listeners, significantly superior to domestic models in their ergonomic characteristics: significantly lower weight and dimensions, digital display and control of the receiver, many service amenities, which makes the process of using them a pleasure. And although our market is rarely pleased with the availability of such devices for sale, the presence of the necessary information about them suggests itself - we will work for the future. Therefore, we continue our acquaintance with modern imported radio receiving equipment, intended both for just radio listeners and for “cool” DX players. But first, some advice for buyers of imported radios.

There are a number of factors to consider when purchasing a receiver. Firstly, the financial capabilities of the future owner. But not only. Much depends on the purpose for which the receiver is purchased: just to listen to international broadcasting stations that operate at high power and carefully choose the location of their repeaters, or to “hunt” for remote, low-power and little-known exotic stations, i.e. engage in DXing. So instead of advice, the characteristics of the receivers and their prices are usually given, and the radio amateur decides for himself what to choose.

The parameters of radio receivers can be assessed objectively - such an assessment by the WRTH directory is carried out annually in various categories, which is quite understandable, since expensive communication receivers are superior in their parameters to cheap portable ones, but their prices are incomparable. Now we will dwell in more detail on some types of imported radios. This article is also based on information from WRTH directories, which, unfortunately, are available to very few radio amateurs.

One more preface. Modern imported radio receivers are divided into three main groups according to the method of tuning to the station and the type of scale:
with mechanical scale: have several extended KB ranges (sometimes their number reaches 13);
with digital scale, but with mechanical adjustment to the frequencies of received stations;
with digital scale and synthesizer push-button or valcoder tuning to the frequencies of received stations.

Receivers with a mechanical scale have weak local oscillator stability, but allow smooth adjustment to the received station on short waves, regardless of whether its operating frequency corresponds to the 5-kilohertz grid, and in the case of an interfering station on the adjacent channel on one side of the received station and with weak selectivity ( selectivity) of the receiver is sometimes helped by detuning from it by moving the receiver tuning frequency in the direction opposite to the interference.

Receivers with synthesizer tuning - the so-called "digital" (not to be confused with the new promising class of digitally modulated signal receivers) - have very good local oscillator stability, but have discrete (often in steps of only 5 kHz per KB) tuning across bands. This results in inconveniences in the cases described above, which, however, are compensated by the presence of many other service amenities provided by their electronic filling,” electronic scanning, long-term memory for frequencies, names of stations, programs, RDS (Radio Data System), etc. It's almost a minicomputer in the receiver. Unfortunately, digital scales and heterodyne synthesizers sometimes create additional interference with radio reception: itching, noise, affected points in the ranges.

A common property of almost all portable receivers is that in the FM band the battery consumption is 1.5 times or more higher than the energy consumption in the AM bands.

The most common English abbreviations used when describing imported receivers:
A.M.— ranges with amplitude modulation (LW, MW, KB);
LW- long waves;
M.W.- medium waves;
SSB— single-sideband signal without carrier;
S.W.- short waves;
FM— ultrashort waves (frequency modulation);
LCD— liquid crystal display;
PLL— automatic frequency control (in synthesizers).

Receiver performance ratings are made using a five-point system with stars: ***** = excellent, **** = good, *** = satisfactory, ** = bad, * = very bad.

Radio receiver SONY ICF-SW10

Sensitivity ****
Selectivity ***
Dynamic range***
Overall rating ***
Dimensions: 162x94x33 mm. Weight: 342 g, including two AA batteries (R6) or, in our opinion, 316.

We present the SONY ICF-SW10 receiver (the only receiver with a mechanical scale in our review) due to its greatest prevalence in the corresponding brand stores. It was released in 1994. By the way, I also own such a receiver, so I also have something to say about it.

SONY ICF-SW10 belongs to the group of portable receivers that can be carried in a bag (possibly in a belt purse) or in a small suitcase or briefcase. Can also be worn hanging on the wrist thanks to the matching cord-loop. When the receiver is located on the surface of something during radio reception, for its stability and good sound perception, there is a folding support-stand on the rear wall of the receiver.

The receiver has one frequency conversion. The European version of the receiver has the following bands (from right to left): FM 88-107 (for some reason, not 108), MW, LW and 9 stretched, but with a solid margin on the sides, SW bands: 13, 16, 19, 22, 25, 31, 41, 49 and, for some reason, 60 (mostly tropical range), and not 75 m (as for Europe). Although I solved this problem very simply - using a core, I rebuilt the heterodyne circuit of this last range so that the receiver would catch the same 60 m with a lower-frequency local oscillator, and 75 m with an upper-located one. At the same time, to adjust the input circuit at 75 m, it is enough to touch its telescopic antenna with your hand - the introduced capacitance is quite enough for the desired effect. The receiver scale is very rough and is unsuitable for determining the exact frequency of a station. Therefore, the receiver is more suitable as a travel receiver for those who like to listen to fairly well-known and well-audible radio stations. For music lovers, when receiving FM stations, stereo reception is possible on stereo head phones.

The sensitivity of the receiver in nature is not bad, but due to mirror interference, as well as strong (even in the NE and LW) interference from VHF stations and television (in large cities), it sometimes deteriorates significantly.

At an average sound volume, the batteries last for approximately 34 hours of continuous operation, which is regarded as a very economical energy consumption (on FM this figure is one and a half times worse). It should be noted that the most economical mode of operation of all pocket and portable receivers is created when using headphones instead of a loudspeaker. For people who travel for a long time, the best solution to the power problem is the use of rechargeable batteries and a solar panel. The receiver also has a small-sized socket for connecting an external power source, which allows you to save battery energy under stationary conditions of use.

Radio receiver GRUNDIG YACHT BOY 400

Sensitivity *****
Selectivity *****
Dynamic range***
Overall rating *****
Dimensions 180x120x37 mm, i.e. approximately the size of a brochure. Weight with 6 AA batteries (a bit too much!) 708 g.

Class of 1993. Winner of the 1994 WRTH Award for Best Portable Receiver. Perfectly executed, at a reasonable price, it offers the radio listener both convenience when tuning into a station and good sound quality. In terms of cost, it is considered the best portable receiver on the world market.

Wave bands: FM, LW, MW and continuous SW band (1.6...30 MHz). A single-conversion receiver with digital tuning and indication: to tune in to the station you need, just dial its frequency on a keyboard that resembles the layout of a telephone or calculator keyboard. Further tuning up or down in frequency can be done using two other keys labeled “TUNING”, and, on short waves, the tuning step can be selected 5 or 1 kHz. The receiver has two IF path bandwidths, and both filters have a good shape factor for portables.

The speaker fits well with the body, so the sound quality of the receiver is much richer and fuller than that of competing Japanese portables.

The receiver is quite sensitive, without serious problems with overload in the European zone. Its memory can store 40 stations. Like most receivers, it has the ability to scan across the range and stop when the signal is strong enough to be heard.

Some compromises involve the need to reduce the price of the receiver. It is almost impossible to obtain clear sound when receiving SSB signals (with one sideband) due to the lack of a smooth tuning knob, and there is no synchronous detector. But the 5.5 and 3 kHz filters at -6 dB are a big plus for the receiver.

In the FM range 87.5-108 MHz you can listen to stereo broadcasts on stereo phones. Sensitivity on FM in Europe is close to optimal, but in the cities of North America (as well as here in Kiev in the range of 100-108 MHz) it turns out to be excessive due to the high congestion of this range there. This manifests itself in mutual interference from stations that are close to each other in frequency, especially when there is a large difference in their power or reception conditions.

The display can be illuminated in the dark and indicate two times: local and UTC.
Duration of operation is more than 20 hours from fresh alkaline batteries when using the receiver for 1 hour per day. It is possible to connect an external power source. The receiver automatically turns off after a certain time, which is very convenient if the listener falls asleep.

Interesting information: The Grundig Yacht Boy 400 is produced in North America, where it is very popular, and in China, with the latter performing better than the double-conversion Yacht Boy 500, made in Grundig's own facility in Portugal.
The Yacht Boy 400PE version differs from the Yacht Boy 400 mainly in its shiny aluminum front panel.

Radio receiver SONY ICF-SW100(S/E)

Sensitivity ****
Selectivity ****
Dynamic range ****
Overall rating ****
Dimensions 111 x 73 x 24 mm are close to the size of a cigarette pack, and the weight, including two AA batteries and a protective case made of soft leather, is 240

This receiver was born as a compromise between small size and good performance when receiving short waves (although I am almost sure that the smaller the receiver, the worse its receiving properties). It adopted the best characteristics of its predecessor Sony ICF-SW1 and at the same time the shape and size of pocket calculators and electronic laptops that are now fashionable among businessmen. The hinged cover houses a tiny loudspeaker and LCD display, and the base contains 28 receiver control buttons.

Single conversion receiver. Most versions of the receiver have an FM range of 76-108 MHz, which also takes into account the Japanese standard of 76-90 MHz, and a continuous AM range of 150-30000 kHz. The version sold in Italy does not have a short wave range below 3850 kHz due to national legislation. On FM in Europe, reception in stereo with stereo speakers gives excellent results, but in areas with high FM signal levels, reception is poor. In this regard, the presence of a DX/LOCAL switch provides some relief from overloads.

But this receiver gives you its most impressive capabilities when working in the AM bands. There are several ways to tune into a station:
— by typing a known frequency on the keyboard, while the frequency and the corresponding range in meters are displayed on the display;
— using four arched arrow keys, you can automatically adjust the frequency up/down the scale in steps of 5 kHz (protruding keys) or 1 kHz (recessed keys).

If you press these keys for more than a few seconds, the receiver goes into scan mode until it tunes to a strong station, allows you to listen to it for a few seconds, and then continues scanning; using a memory in which up to 50 radio stations can be “stored”, each of which is placed on a page with its name, abbreviated to 6 letters, the type of modulation and the five frequencies it uses. The receiver usually comes with 30 programmed frequencies that are regularly used: 10 from the BBC, 10 from the Voice of America and 10 from R. Japan. But you can easily erase them and replace them with others.

The receiver is the first of its size to have a synchronous detector. In this mode, the receiver is more sensitive and has the ability to separately receive the lower or upper sideband. If, for example, a neighboring station is interfering with the one you are receiving, then by tuning into the sideband opposite to the interference, you can get rid of this interference as much as possible. Another important advantage of single-sideband broadcast radio reception compared to two-sideband is the absence of selective fading - especially during deep fading, when using synchronous detection, you notice a reduction in distortion compared to conventional AM.

The receiver also has a mode for receiving SSB signals with lower or upper sideband. In SSB mode, the recessed automatic frequency adjustment keys change the tuning step to 100 Hz, although this is not shown on the display. Unlike the Sony ICF-SW55, which has an automatic AM/SSB operating mode detection depending on the frequency you select and, outside of broadcast areas, switches to SSB on its own without your desire, the ICF-SW100 is devoid of this annoying function and is therefore more convenient to use.

For recording from the receiver to a tape recorder, there is a special linear output jack with a constant signal level on it.
The duration of continuous operation of the receiver is about 17 hours when listening to KB and using fresh alkaline batteries.

Radio receiver SONY ICF-SW7600G

Sensitivity***
Selectivity ***
Dynamic range***
Overall rating ****
Dimensions 191x118x32. Weight 615 g.

Receiver with double conversion on SW, which allows you to get rid of specular interference. Received frequency ranges AM 150-29999 kHz, FM 76-108 MHz. Setting up the station is done using four keys, similar to the ICF-SW100. Tuning step: on MW - 9 kHz (for Europe), 10 kHz (for America), 1 kHz (in more complex cases); on SW there are two tuning steps: 5 and 1 kHz. There are scanning modes with fixation on the first loud station, synchronous detection and reception of SSB signals. In SSB mode, fine tuning to a station is possible using a knob located on the side of the receiver.
For recording from the receiver to a tape recorder, there is a special linear output jack with a constant signal level on it, but only mono. Stereo signal is available only at the phone socket.
The receiver has 22 memory cells: 10 for AM, 10 for FM and 2 for the frequencies of your favorite stations to the sound of which you want to wake up (alarm clock). The display shows the time only when the receiver is turned off, and when the receiver is on, the tuning frequency is accurate to 1 kHz.

As for the characteristics, for this type of receiver, double conversion is implemented well. The level of appearance of intermodulation on the input signal is -6dBm. But in Europe you can forget about an outdoor antenna at night. To improve daytime radio reception at higher shortwave frequencies in more remote areas of the world, a simple Long Wire antenna is recommended. The overload that occurs when using a telescopic whip antenna can be easily eliminated by shortening it.

The selectivity of the receiver is undoubtedly sufficient for listening to broadcasts from international broadcasting stations. The receiver has an IF filter with only one passband, but this disadvantage is compensated by the presence of a synchronous detector. Current consumption from the battery is 50 mA at normal volume, which corresponds to about 23 hours of operation from four fresh alkaline batteries. To reduce the price of the receiver, a power supply is not included in the package. The ICF-SW7600G uses the new Japanese 6V DC power standard with a smaller plug. When purchasing a different type of power supply, check that the voltage polarity on the plug is correct. To store stations in memory, the batteries must be in the receiver, even when the power supply is connected. Batteries should be changed within no more than 10 minutes.

So the ICF-SW7600G is a very smartly packaged device at a reasonable price, although it doesn't have as much memory as the more expensive ICF-SW100. And although the similarly priced Grundig Yacht Boy 400 sounds better, the ICF-SW7600G synchronous detector has an advantage in terms of dynamic selectivity, and the synthesizer noise in it is lower.

I’ll add that the 7b00ok family dates back to 1984, when the ICF7600D was released (its version ICF-2002 was released in North America). Since August 1987, with a decrease in price and a change in color, the receiver began to be designated as ICF-7600DS (ICF2003 in North America). However, the short-wave parameters of all these options were identical. In January 1990, Sony improved its 7600, adding stereo to FM and improving its SSB reception: adding a high and low band selector and a fine tuning knob. The name changed to ICF-SW7600, but the price remained around $250. With the release of the ICF-SW7600G, Sony made significant improvements to it (in particular, adding a 1-kilohertz tuning step to the 5-kHz tuning step) and reduced the price in Europe to $180.

Radio receiver SONY ICF-SW33


Sensitivity ****
Selectivity ****
Dynamic range ****
Overall rating ****
Dimensions 165x93x29 mm. Weight 423 g with 3 AA batteries. DC current consumption is 35 mA at average sound volume, which is considered very economical for receivers with a PLL synthesizer. Class of 1992

Portable double conversion digital receiver, considered by Sony as an intermediate between the popular digital ICF-SW7600 and analog ICF-SW7601. Most receiver versions have MW, FM and 11 short wave bands: 3700-4200, 4650-5150, 5800-6300, 6950-7450, 9375-10000, 11525-12150, 13375-14000, 14975-15600, 17475 -18100, 21320-21950 and 25475-26100 kHz, i.e. 75, 60, 49, 41, 31, 25, 22, 19, 16, 13 and 11 m. Thus, some frequencies and the new 15 m band are still "dropped out", although most bands include extensions according to decisions of the World Administrative radio conferences WARC-92 and some even with excess margin. With telephones you can listen to FM stations in stereo. There is no stereo indicator, and when the signal becomes weak, the receiver automatically switches to mono mode.

The receiver does not have a keyboard for dialing frequencies, so tuning to a station can only be done using the UP/DOWN keys. On FM the tuning step is 50 kHz, on MW - 9 or 10 kHz and on SW -1 kHz. Therefore, a smooth transition on short waves from one end to the other takes quite a long time. To speed up “jumping” across SW ranges, you must press both keys simultaneously. This will allow you to find the lower frequency of each range very quickly. In addition, there are 5 memory channels for SW, 5 for FM and 5 for MW. Using them, you can move through the ranges even faster. The remaining two channels are programmed for an alarm clock, which uses the stations you and your partner love, i.e. Different stations come on at different times. The SCAN button turns on the scanning mode until it is tuned to a loud station, then after a few seconds of stopping, scanning resumes. A second press of the button stops scanning. There is no SSB mode.

When you press the small button on the top of the receiver, the LCD indicator lights up green for 20 seconds. The receiver also has a memory of the time in 38 cities around the world.
This dual conversion receiver is undoubtedly superior to other single conversion receivers at a price to match. This is especially noticeable during night radio reception in Europe. It has only one filter with a 5 kHz bandwidth at -6 dB (similar to the ICF-SW7600).

There is an attenuator on the side of the receiver that reduces the input signal level by 20 dB. In some areas of short waves it is quite rough, but for medium wave reception it is excellent.
The noise of the synthesizer is quite acceptable - at least less than that of earlier versions of the very expensive ICF-SW77. The sound quality from the small speaker is surprisingly rich and, with hi-fi headphones, highly fidelity.

Radio stations operate in the medium wave range, their signals literally surround us. To assemble an amplitude modulation radio (AM receiver), you will need a few simple parts: some electronic components, wires, a paper tube, and a speaker. Assembling the AM receiver is quite simple and does not require any soldering. With such a simple receiver you can pick up signals from radio stations that are within 50 kilometers.

Steps

Part 1

Prepare everything you need

Prepare what you will need. You may already have most of the parts you need, with the exception of some electronic components. Missing parts can be purchased at a hardware or electronics store. You will need the following:

• resistor with a resistance of 1 megaohm;
• capacitor with a capacity of 10 nanofarads;
• red and black insulated wires 25–50 centimeters long;
• variable capacitor with a capacity of 2000 or 2200 picofarads;
• electrolytic capacitor with a capacity of 22 microfarads;
• capacitor with a capacity of 33 picofarads;
• insulated wire 15–30 meters long (any color, for the antenna);
• 9-volt battery;
• bread board;
• insulating tape;
• operational amplifier (op-amp);
• a small non-conductive cylinder (glass bottle, cardboard or plastic tube, etc.);
• speaker;
• wire cutters (or something similar, such as sharp scissors or a knife).

1. Make an antenna. This is one of the simplest parts of a homemade radio: all you need is a long piece of wire. It's best to use a 15 meter piece of wire, but if you don't have that long of wire, 5-6 meter long wire will do.

   • For the antenna, insulated wire with a diameter of 0.7–0.8 millimeters is best suited.
   • To make the antenna better receive the signal, roll the insulated wire into a ring. To prevent the wire from tangling, secure it with a cable tie or electrical tape. Fold a 15 meter long piece of wire about five times into a ring.

2. Cut and strip the connecting wires. With these wires you will connect the components on the electronic circuit layout. Cut one piece of red and one black wire about 12 centimeters long.

   • Using wire cutters, strip 2-3 centimeters off both ends of each wire.
   • If the connecting wires turn out to be too long, they can always be cut, so it is better to make them with a small margin first.

3. Make an induction coil. Wrap the wire tightly around the cylinder without gaps between adjacent turns so that it receives radio waves carrying electromagnetic energy. It's not as difficult as it seems at first glance. Simply thread red and black wires 25–50 centimeters long onto the cylinder.

   • Start winding the wire from one end of the cylinder. Leave about 12 centimeters of wire free at the end to secure it with insulating tape to the edge of the cylinder. Wind the wire tightly without any gaps between adjacent turns.
   • Select a cylinder with a diameter of 5–8 centimeters. It should not be metal, otherwise the received signal will go through the metal.

4. Completely wrap the cylinder with wire to create an induction coil. The more turns you get, the better. Cover the entire cylinder with wire. Secure the end of the wire with insulating tape, measure about 13 centimeters at the other end and trim off the excess wire.

   Connect a 22 microfarad (µF) electrolytic capacitor. Place the long lead of the 22 µF capacitor on the top half of the breadboard in the hole directly above the top terminal of the 1.0 M resistor. Insert the short lead of the capacitor into the hole four rows to the right.

   Install the connecting wires. Insert one end of the red wire into the hole above leg 8 of the op-amp, and the other into the nearest hole in the top long row of the breadboard, where the holes are connected horizontally. Insert one end of the black wire into the hole under amp leg 1 on the bottom half of the breadboard. Insert the other end of the black wire into the bottom long row of the layout.

   Install a 33 picofarad (pF) capacitor. Take a look at the 10 nF capacitor. One of its terminals is connected to the bottom leg of the amplifier, and the second is inserted into a free hole, but is not yet connected to anything. Insert one lead of the 33 pF capacitor into the hole above the free lead of the 10 nF capacitor. Insert the second lead of the 33 pF capacitor into the free hole four rows to the left.

   • This capacitor, like the previously installed 10 nF capacitor, has no polarity and allows current to pass in both directions. So it doesn't matter which pin is used where.

Part 3

Connect the remaining components

1. Connect the antenna. It's time to connect the antenna. Insert one end of the antenna into the hole above the free lead of the 33 pF capacitor (you moved this lead four rows to the left in the previous step).

   • To improve signal reception, you can spread the antenna wire around the room or twist it into a ring, as described above in the antenna preparation step.

2. Connect the variable capacitor. Insert one lead of the variable capacitor into the hole above the right terminal of the 33 pF capacitor. Place the second lead in any hole in the very bottom row of the layout, where it will connect to the black wire.

   Connect the inductor. Use the free ends of the wire about 12 centimeters long that are left on both sides of the coil. Insert one end into the hole in the bottom row of the breadboard where it will connect to the variable capacitor and black wire. Insert the second end of the wire from the coil into the hole in the row where the 10 nF capacitor and the electrolytic capacitor are connected.

   Connect the speaker. Place the speaker on the table to the right of the variable capacitor. The speaker has two terminals, black and red. Unravel them and get them ready to join. Insert the red speaker lead into any hole on the very top row of the breadboard where it connects to the red wire. Place the black speaker wire in the hole above the short lead of the 22 µF electrolytic capacitor.

   • You will probably have to unwind the red and black speaker wires so they can be connected to the circuit.

3. Connect the power supply. After you assemble the circuit, you need to provide it with power. Using electrical tape, connect the wires to the positive and negative terminals of the 9-volt battery. Then do the following:

   Troubleshoot possible problems. Electrical circuits are quite tricky, especially if this is your first experience. Check that all wires are securely inserted into the holes and that all components are connected to the correct terminals.

• Don't be discouraged if the receiver doesn't work after the first try. Assembling electrical circuits requires some skill - it will likely take some practice before you can assemble a working radio.
• Check if all components are working properly. If you have assembled the circuit correctly and made sure that all contacts are reliable, it is possible that the problem is a malfunction of some components. Capacitors, resistors and op-amps are very cheap and produced in large quantities, so sometimes there are faulty components among them.
• Buy a voltmeter that you can use to test the circuit. A voltmeter allows you to measure the current that flows through the section of the circuit you are interested in. Voltmeters are pretty cheap. With this device you can check the components of the circuit and the reliability of their connections.

Warnings

• Do not overload the circuit with too high voltage. If you apply more than 9 volts, the components may fail and even catch fire.
• Do not touch bare wires while current is flowing through the circuit. Otherwise, you may get an electric shock. However, since this circuit uses a low voltage battery, the shock will not be severe.
• Do not connect the short lead of the capacitor to the positive terminal of the voltage source. If you do this, there will be a popping sound, the capacitor will release a small cloud of smoke and fail. In the worst case, it may catch fire.

What you will need

• 1 resistor with a resistance of 1 megaohm
• 1 10 nanofarad capacitor
• Red and black insulated wires 25–50 centimeters long
• Variable capacitor with a capacity of 2000 or 2200 picofarads
• 1 electrolytic capacitor with a capacity of 22 microfarads
• 1 capacitor with a capacity of 33 picofarads
• Insulated wire 15–30 meters long (any color, for antenna)
• One 9-volt battery
• Bread board
• Insulation tape
• 1 operational amplifier (op-amp)
• A small cylinder of non-conductive material (glass bottle, cardboard or plastic tube, etc.)
• Speaker
• Wire cutters (or something similar, such as sharp scissors or a knife)