AM radio receivers are designed to receive amplitude-modulated signals with a frequency typically not exceeding 30 MHz.
Main parameters: supply voltage - 9 V±10%; current consumption - 16 mA; input voltage - no more than 50 µV; output voltage LF AM >30 mV; >1.55 V; harmonic coefficient of the low-frequency signal - up to 2%; signal-to-noise ratio - over 20 dB.
A dual-band AM radio receiver with a field-effect transistor input stage (Fig. 41.10) is operational in the supply voltage range from 3 to 9 V.
Rice. 41.9. Chip structure
Coils LI, L2 each contain 65 turns of PEV-2 0.27 mm wire, wound in bulk on paper sleeves with a diameter of 10 mm. Inside the sleeves there are pieces of 600NN ferrite rods with a diameter of 8 mm. Communication coil L3 is wound on top of coil L2 and contains 2 turns of the same wire. Coil L4 - without a frame, has an internal diameter of 3 mm and contains 6 turns of PEV-2 wire 0.41 mm.
K174ХА36 (the structure is shown in Fig. 41.13, and the inclusions are shown in Fig. 41.14) is intended for use in AM radio receivers.
Rice. 41.13. Internal structure of the K174XA36 chip
Contains a mixer, radio frequency, intermediate and low frequency amplifiers, a detector and an AGC system. The microcircuit can be used in radio receivers with low (3 V) supply voltage, transceivers, security alarm and radio control systems.
The supply voltage of the microcircuit is from 2 to 9 V (for K174XA36A) and 2-3.3 V (for K174XA36B) at maximum current consumption
3-20 mA. The sensitivity of the radio receiver with a signal-to-noise ratio of 20 dB at a receiving frequency of 1 MHz is no worse than 15 µV. The output voltage of the AM detector is up to 0.3 V. The gain of the LF preamplifier is 3-7. The intermediate frequency is determined by the IF filter (usually 450-470 kHz). Fine tuning indicator current on LED HL1 -
Rice. 41.14. radio receiver on a KΚΙ 74ХА36 microcircuit
Shustov M. A., Circuitry. 500 devices on analog chips. - St. Petersburg: Science and Technology, 2013. -352 p.
This receiver is designed to receive amateur and broadcast stations over a wide continuous range from 3.5 to 22 MHz. The setting is analogue, using a two-section block of variable capacitors and a roller-thread vernier-scale mechanism. The adjustment scale is a ruler almost 40 cm long. The circuit is transistor, the body is wooden, varnished, the installation is three-dimensionally printed on “heels” cut into the foil of a sheet of foil fiberglass. I admit, now all this looks very primitive, but I wanted to make just such a “nostalgic” short-wave receiver.
And yet, the receiver uses very accessible and inexpensive radio components, which allows it to be assembled not only by urban, but also by rural radio amateurs. Moreover, almost all the parts can be taken from the disassembly of old TVs and other equipment.
The circuit diagram is shown in the figure in the text. The circuit is superheterodyne with one frequency conversion.
The signal from the antenna is supplied to the input circuit L1-C2-C4.1 through the tap of the coil L1 and the variable resistor R16, which serves as a sensitivity regulator. This receiver does not have an automatic gain control; sensitivity is adjusted only manually using this resistor. Moreover, at the very input of the receiver - before any transistor stages. This allows, when receiving powerful radio stations, to completely eliminate overload of the frequency converter, and when receiving weak and remote radio stations, to ensure the greatest sensitivity, which will not be reduced by the AGC system, which erroneously responds to interference.
The input circuit is rebuilt by one of the sections of the variable capacitor C4 with an air dielectric. Here we use a two-section capacitor of the KPE 2V type with a capacity of 10-495 pF per section, from an old radio or tube receiver. The SZ capacitor is installed to protect against a possible short circuit in the variable capacitor.
The frequency converter is made using transistors VT1 and VT2. This is a converter with a combined local oscillator, made on the basis of a cascode amplifier stage. The input signal from the input circuit through the coupling coil L2 is supplied to the base of the transistor VT1, which performs the functions of both a mixer and a local oscillator. For the input signal it is connected according to a common emitter circuit, and as a local oscillator - according to a common collector circuit.
The local oscillator frequency is set by circuit L7-C20-C19-C4.2. Capacitor C19 ensures pairing of the settings of the input and heterodyne circuits, taking into account the intermediate frequency of 455 kHz. Of course, such a simple pairing method does not provide high accuracy, and therefore the sensitivity of the receiver within the entire range of 3.5-22 MHz is uneven.
The intermediate frequency is isolated in the L3-C8 circuit and is fed through a coupling coil to the Q1 bandpass piezoceramic filter, with an average frequency of 455 kHz. It uses an affordable piezo filter from an imported AM pocket radio. Therefore, the intermediate frequency is 455 kHz. Using a domestic 465 kHz filter, the intermediate frequency will be 465 kHz. Of course, you can use a 2-3-stage LC filter of concentrated selection, but setting up the receiver will be much more complicated.
The intermediate frequency amplifier is assembled on transistors VT3 and VT4, forming the same cascode amplifier as on transistors VT1 and VT2, but purely an amplifier, without mixing and heterodyne functions (the emitter circuit VT3 is closed to a common minus, and does not go to a heterodyne coil). Circuit C12-L5 is a pre-detector circuit. The demodulator is made on transistor VT5. Its operating mode depends on the state of S1. In the position shown in the diagram, telegraph and telephone stations (CW and SSB) are received. In this case, a reference oscillator on transistor VT8 is used. The generator frequency is determined by the ceramic resonator Q2, - 455 kHz. If the receiver will use a different intermediate frequency, for example, 465 kHz, then, accordingly, the resonator should be at the same frequency. In principle, you can abandon the resonator and use an LC circuit, for example, an IF circuit from a pocket AM receiver, or the same circuit as, for example, L3-C8, connecting it between the VT8 base and the common minus through a decoupling capacitor with a capacity of 1000 pF .
The reference oscillator is powered by a parametric stabilizer on VD1.
When receiving CW and SSB, the reference frequency voltage from the emitter VT8 is supplied to the emitter of the transistor VT5, which acts as a demodulator. In this transistor, frequency conversion occurs and a complex signal of the sum-difference frequency is released at its collector. The total frequency is suppressed by the simplest low-pass filter R11-C14, and the difference frequency passes through it and goes to the volume control R12.
When working to receive AM signals, switch S1 must be set to the opposite position shown in the diagram. In this case, the VT5 emitter is closed to a common minus through S1.1, and the reference oscillator is turned off by S1.2. Now the VT5 transistor works as an efficient high-sensitivity transistor detector. At its output, a low-frequency signal is released, which is fed to R12.
The low-frequency telephone amplifier is made using transistors VT6 and VT7. The load is headphones with a resistance of at least 30 Ot.
The receiver is powered from a simple network source using a low-power transformer T1 and a diode bridge VD2. The supply voltage of the circuit is about 8V. Lamps H1-NZ serve to illuminate the receiver setting scale and at the same time serve as indicators of the on state.
The entire circuit is assembled by volumetric installation “on the heels” on a panel welded from foil fiberglass. The panel has dimensions of 20x15 cm. The panel has shielding sections made from strips of the same foiled fiberglass about 2 cm wide. There are five sections in total, for the reference oscillator (VT8), for the converter and input circuit (VT1-VT2), for the IF amplifier and PPF (VT3-VT4), for the demodulator (VT5) and for the low-frequency amplifier (VT6-VT7).
The section with the converter is large, it is made so that the local oscillator and input circuits are located on different sides of the variable capacitor C4, which is also installed on this common panel. The C4 scale drive is common, used in many receivers - a large pulley, two rollers, one of which is mounted on the tuning knob, and a rope scale with a spring tensioner. The scale is linear, paper. Lamps H1-NZ are located above the scale, so that they are covered by the front panel of the receiver housing and do not shine into your eyes, but only onto the scale.
The receiver body is wooden, rectangular, dimensions 430x115x200 mm.
All transistors are KT3102A. You can use any other KT3102, or older KT315, KT312.
As already mentioned, the Q1 piezoceramic filter is suitable for any broadcast receiver with AM bands.
Variable capacitor C4 - doubled with an air dielectric from an old Record-354 radio. Any 10-495 pF will do.
Power transformer T1 is Chinese with a 6V secondary winding. You can use a transformer from the power supply of a television game console like “Dandy” or an old TVK-110 from a tube TV. In general, the voltage at C27 should be 8-10V.
Variable resistor R1 must be installed as close as possible to the antenna socket.
To wind all the coils, frames from color modules of old TVs of the USCT type were used. These are frames with a diameter of 5 mm with ferrite tuning cores.
Coil L1 - 19 turns with tap from the 5th. Coil L2 -5 turns. Coils L3, L5 and L9 - 85 turns each. Coils L4, L6, BUT - 10 turns each. Coil L7 - 17 turns, L8 - 5 turns with a tap from the 2nd. Coils L1, L2, L7, L8 are wound with PEV 0.23 wire. All other coils are wound with PEV 0.12 wire, turn to turn.
First, a contour coil is wound, then a communication coil is wound on its surface. The coils can be sealed with paraffin.
Setup is traditional for a superheterodyne receiver. When setting up IF circuits, you can use either a signal generator or any broadcast receiver with AM bands and the same intermediate frequency as in this circuit. In this case, the signal with the IF frequency must be removed from the pre-detector circuit of the model receiver and fed through a small capacitor, first to the VT3 base, then to the VT1 base (after turning off the local oscillator and shorting the VT1 emitter with a jumper to a common minus).
Setting up the local oscillator, setting the range and pairing the settings of the input circuit must be done using an RF generator, or by receiving signals from radio stations of a known frequency, and checking the scale of a model receiver.
The last stage is marking the scale; this is most conveniently done by receiving signals from an HF generator with AM modulation, but it can also be done using standard receiving equipment.
Ivanov A.
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.
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 wave SW (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 Kyiv 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, 17475-1 8100, 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.
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TDA2613 is an integrated ULF designed for operation in household equipment (television and radio receivers). There is short circuit protection and thermal protection. Main characteristics of the microcircuit: Supply voltage 15...42 V SOI: (Upit=24 V, Rn=8 Ohm, Rout=6 W) - 0.5% (Upit=24 V, Rn=8 Ohm, Rout=8 W ) - 10% Quiescent current...
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The output stage for an electronic siren must provide high signal output and the lowest possible current consumption in the absence of a signal. The output stage to ensure maximum volume is made on VT1-VT4. The role of the bass reflex is performed by element D1.2. It switches the transistors one by one, so the signal level at the head doubles. In order for the current to be in standby mode...
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Based on the LM3914 IC, you can design various LED indicators with a linear scale. The LM3914 is based on 10 comparators. The input signal through the operational amplifier is supplied to the inverse inputs of the LM3914 comparators, and their direct inputs are connected to a resistor voltage divider. Ten outputs are comparator outputs to which LEDs are connected. The figure shows a diagram...
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A binaural converter is a device that significantly reduces the localization effect of apparent sound sources in the listener’s head and reduces the unnatural sharp separation of channels that usually occurs when listening to stereo soundtracks through stereo phones (headphones). Such a converter brings the quality of playback through headphones closer to the quality of playback through speakers. Characteristics of the binaural converter: Nominal input voltage 0.8V ...
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