SSB detector in a broadcast receiver. Encyclopedia of radio electronics and electrical engineering

Encyclopedia of radio electronics and electrical engineering / radio reception

 Comments on the article

In printed publications and on the Internet, there are materials about the conversion of old radios to receive SSB signals, which indicates the interest of radio amateurs in this topic. In this article, the author proposes a device that makes it possible to receive SSB signals to household radios and radios with an AF-AM path, electronic frequency tuning and internal supply voltages of +5 V and +9 V. The author built it into the Salyut 001 radio receiver (briefly described in [1], more fully - in [2]), but it is also suitable for many other receivers and radio tape recorders, in particular, "Kazakhstan 101-stereo" [2], "Ocean-221" [3], "Meridian-235" [3], "Oreanda 203-stereo" [3].

Rice. 1 (click to enlarge)

The scheme of the proposed device is shown in the figure. It contains an input amplifier based on transistor VT1, loaded with an L1C9 circuit tuned to an IF frequency of 465 kHz, a mixing detector on diodes VD3 and VD4, a low-pass filter R9C16L4C18, a notch filter L5C20, a local oscillator on logic elements DD1.1 and DD1.2, the frequency of which stabilized by a piezoceramic resonator ZQ1, buffer amplifiers for the local oscillator voltage - elements DD1.3 and DD1.4, a rectifier with diodes VD1 and VD2, a diode VD5 used as a stabistor, R12 - a voltage regulator for manual tuning of the local oscillator frequency (HRCG).

The input of the device is connected to the output of the IF receiver. Transistor VT1 serves not so much to amplify the IF voltage, which may be quite sufficient for the operation of the mixing detector, but to eliminate the influence of the mixing detector on the receiver. A tuning resistor R1 is included in the source circuit of the transistor VT4, the engine of which sets the required gain. In the drain circuit of the transistor VT1 - half of the winding of the inductor L1 of the inverter circuit L1C9. Partial inclusion of the circuit is applied, since at full the transistor shunts the circuit, due to which its quality factor decreases and the bandwidth expands. The supply voltage +9 V is supplied to the transistor VT1 through the resistor R8 and the coil L1.

The inductors L1 and L2 form a high frequency transformer.

The tap from the middle of the winding of the L2 coil is connected to a common wire, and its beginning and end are connected to the diodes VD3 and VD4 of the mixing detector SSB, loaded by the IF resistor R9. To the connection point of these three elements through the capacitor C13, the local oscillator voltage is applied from the output of the logic element DD1.4. Resistor R9 prevents the local oscillator voltage from shorting to a common wire through capacitor C16. These components also form the first section of the low pass filter. The second link is the L4 coil and the C18 capacitor.

The local oscillator is assembled on inverters DD1.1 and DD1.2, which are switched to linear mode by negative feedback circuits through resistors R1 and R3; it includes capacitors C1, C3-C5 and a piezoceramic resonator ZQ1, which sets the generation frequency. The local oscillator creates a pickup on the IF path, which affects the AGC system, reducing the gain, and leads to the appearance of additional interference noise. To eliminate it, a notch filter was used - a serial circuit L5C20, which is connected to the base of the transistor VT2 in the A2 "HF-AM" block of the "Salyut 001" receiver (see the diagram in Fig. 1.52, p. 62 in [2]). In other receivers, the notch filter is installed in the presence of interference, the point of its connection is selected experimentally.

The local oscillator voltage at the outputs of the elements DD1.1 and DD1.2 has a shape close to a sawtooth and an amplitude of about 2 V. The elements DD1.3 and DD1.4 are buffer amplifiers-local oscillator voltage limiters. The output voltage of the element DD1.3 through the current-limiting resistor R6 and the capacitor C11 is supplied to the rectifier on the diodes VD1 and VD2. The rectified voltage limits and stabilizes the Schottky diode VD0,3 at a level of about 5 V. It is fed into the diagonal of the bridge on resistors R7, R10 and a variable resistor R12. The voltage from the other diagonal of the bridge - on the engine of this resistor relative to the connection point of the resistors R7 and R10 is used to manually adjust the frequency of the receiver's local oscillator. By moving the slider of the variable resistor R12, the RPCG voltage can be adjusted within ± 0,15 V. Capacitors C14, C15, C17, C19 smooth out the ripple of this voltage.

Manual adjustment of the local oscillator frequency is necessary because the tuning on SSB radio stations, even in extended HF bands, is very "sharp", and the AFC system does not work, since it tunes to a carrier that is not in single-sideband signals. Therefore, while receiving SSB signals, the AFC system must be turned off, and instead of the AFC voltage, the RPCG voltage is applied to the corresponding varicaps.

For this purpose, in the author's copy, the upper and lower voltage outputs of the RPCG according to the circuit are connected, respectively, to terminals 15 and 14 of block A12 (Fig. 1.69 on p. 72 in [2]). Through the printed conductors from these pins, the voltage of the RPCG is applied to contacts 2 and 4 of the switch S3 "APC" (the numbering of the switch pins is shown in Fig. 2 in [1]). To disable the AFC, the button on this switch must be pressed. In this case, contact 4, to which the AFC voltage is applied, closes with contact 6 connected to a common wire, as a result of which the lower voltage output of the RPCG according to the circuit is connected to a common wire, and the upper one, through terminal 15 of block A12, to terminal 19 of block A2 and further (Fig. 1.52 in [2]) through a resistor R4 with a varicap anode that controls the local oscillator frequency of the DA1 microcircuit. For the HF bands 25-49 m, this is the second local oscillator, for the rest of the AM bands, the first. The author installed a variable resistor R12 instead of a variable resistor for adjusting the automatic shutdown (R1 in Fig. 6 in [1]), which he never used.

In the general case, the RPCG voltage is applied so that it is added to another control voltage on the varicap. For example, it can be included in the open circuit of the smooth-tuning variable resistor engine (in "Salyut 001" this is resistor R1 in the above diagram), and the order of connecting the RPCG voltage outputs does not matter.

The device consumes a current of 5 mA from a +4 V voltage source, and 9 ... 12 mA from a +1,5 V source (which can be increased to +2 V when powered from the mains). It is assembled on three boards made of foil fiberglass 1,5 mm thick: the L5C20 notch filter is mounted on the first one, the input amplifier on the VT1 transistor is mounted on the second, and all other components are on the third. The boards are installed in different places of the receiver: the first is closer to the UHF receiver, the second is to the IF output, the third is next to the UHF. The device is turned on by an additional switch installed in the receiver, which connects the +5 V and +9 V supply voltages, as well as the UZCH input, disconnecting it from the AM detector output. If the receiver does not have an internal supply voltage of +5 V, it can be obtained from a voltage of +9 V using a voltage stabilizer chip from the KR1157EN501, KR1157EN502, KR1157EN5, 78L05 series, included according to a typical circuit.

In the author's copy, the input of the device is connected to pin 7 of the DA1 A244D chip (analogous to K174XA2) in the HF-AM (A2) block of the Salyut 001 receiver (see the diagram in Fig. 1.52, p. 62 in [2]). The author recommends just such an input connection for all receivers that use the K174XA2 chip. In general, the input is connected to the output of the IF, for example, to the last IF circuit. If the inductor of this circuit has a tap or coupling coil, the input can be connected to them. In order not to disturb the setting of the IF circuit when fully connected to it, it is permissible to reduce the capacitance of the capacitor C2 to several pico-farads.

The inputs of unused DD1 inverters are connected to a common wire, and their outputs are not connected anywhere. Diodes VD1 and VD2 - any high-frequency silicon. Mixer diodes VD3 and VD4 are chosen as for a direct conversion receiver [4, p. 124] and by the closest possible voltage drop at a forward current of about 1 mA. Diodes ZD112A worked well in the console, but it is difficult to select them in pairs, and they are very fragile. Schottky diode BAT85 (VD5) can be replaced with 1N5817 or two series-connected germanium diodes from the D9 series.

Coils L1 and L2 are wound on a three-section frame under the armored magnetic circuit from two ferrite cups 4,0x8,6 mm from the IF circuits of the Quartz, Sokol, Almaz radio receivers. Conclusion 6 is preliminarily added to the base of the circuit: a hole with a diameter of 0,6 mm is drilled in a free place and a piece of tinned wire with a diameter of 0,75 mm and a length of 7 mm is fused into it. The winding is wound with four pieces of PEV-1 wire twisted together with a diameter of 0,12 mm, 15 turns in each of the three sections of the frame, after soldering the leads, two identical coils L1 and L2 of 90 turns are obtained, with taps from the middle of the windings.

L3 - any small-sized choke with an inductance of 0,22 ... 1 mH, soldered into the gap of the connecting wire and closed with a heat shrink tube. L4 - relay coil RES80T with a resistance of 1,6 kOhm. The relay housing is connected to a common wire by soldering to it a rack of tinned wire with a diameter of 0,75 mm, which also serves as an additional fastening element. As L4, you can use a universal magnetic head, as described in [5]. The L5 notch filter coil contains 125 turns wound in bulk with PEV-1 wire with a diameter of 0,12 mm on an imported frame with a red mark without a built-in capacitor with a ferrite trimmer 8x12 mm. More details about marking the contour coils of imported radio receivers are described in my article [6].

All fixed resistors - any suitable size. The resistance of resistors R7, R10, R12 can be increased to 10 kOhm. Trimmer resistor R4 - SPZ-22, variable resistor R12 - SPZ-4M with functional characteristic "A". Trimmer capacitor C5 - KT4-23. Oxide capacitors - any specified capacity and voltage. The remaining capacitors - KM, KD or similar for a voltage of at least 12 V; C8 - not less than 25 V.

When establishing, the required local oscillator frequency is set and the L1C9 and L5C20 circuits are tuned to it. The author set up a prefix in the Salyut 001 radio receiver, taking into account the features of its circuit and the presence of a narrow bandwidth (NB) mode in the AM bands, the presence of 1 and 2 m amateur radio bands in the KV-80 and KV-40 bands. 001" reception in the HF bands 25-49 m is carried out with double frequency conversion, the local oscillator frequencies are higher than the received frequencies. In this case, a double sideband inversion occurs and the received SSB signal has a lower sideband (LSB). In the ranges of KV-1, SV, DV, the inversion is single, therefore the received SSB signal has an upper sideband (VBP). The UPCH-AM bandwidth of 6 kHz in the UE mode makes it possible to receive signals from the VBP and NBP without distortion at a local oscillator frequency equal to the average frequency of the UPCH-AM passband, but in this case a mirror reception channel appears, as in direct conversion receivers [5 ]. In the author's receiver, the average passband frequency turned out to be 466 kHz, so the L1C9 and L5C20 circuits, as well as the local oscillator, are tuned to this frequency.

The author has been using the device for over a year. Reception is carried out on a telescopic HF antenna "Salyut-001". In the ranges of 40 and 80 m, Moscow and the region are heard every evening, with a good passage, the author listened to the stations of St. Petersburg, Voronezh, Tolyatti, Bryansk, as well as negotiations in Ukrainian and other foreign languages.

Literature

1. Khabibulin V., Brodsky Yu., Grinman G., Kozlov A. Radio receiver "Salyut 001" .- Radio, 1981, No. 5-6, p. 14-17.
2. Belov I. F., Belov V. I. Handbook of household receiving-amplifying radio equipment. - M.: Radio and communication, 1984.
3. Alekseev Yu. P. Household receiving-amplifying radio equipment. Directory. - M.: Radio and communication, 1987.
4. Polyakov V. T. Radio amateurs about the technique of direct conversion. - M.: Patriot, 1990.
5. Belenetsky S. A simple three-band direct conversion receiver. - Radio, 2008, No. 11, p. 52-54; No. 12, p. 64-67.
6. Panshin A. Color marking of contour coils of imported radio receivers. - Radio, 1998, No. 10, p. 26.

Author: A. Panshin

See other articles Section radio reception.

Read and write useful comments on this article.

<< Back

Latest news of science and technology, new electronics:

Artificial leather for touch emulation 15.04.2024

In a modern technology world where distance is becoming increasingly commonplace, maintaining connection and a sense of closeness is important. Recent developments in artificial skin by German scientists from Saarland University represent a new era in virtual interactions. German researchers from Saarland University have developed ultra-thin films that can transmit the sensation of touch over a distance. This cutting-edge technology provides new opportunities for virtual communication, especially for those who find themselves far from their loved ones. The ultra-thin films developed by the researchers, just 50 micrometers thick, can be integrated into textiles and worn like a second skin. These films act as sensors that recognize tactile signals from mom or dad, and as actuators that transmit these movements to the baby. Parents' touch to the fabric activates sensors that react to pressure and deform the ultra-thin film. This ... >>

Petgugu Global cat litter 15.04.2024

Taking care of pets can often be a challenge, especially when it comes to keeping your home clean. A new interesting solution from the Petgugu Global startup has been presented, which will make life easier for cat owners and help them keep their home perfectly clean and tidy. Startup Petgugu Global has unveiled a unique cat toilet that can automatically flush feces, keeping your home clean and fresh. This innovative device is equipped with various smart sensors that monitor your pet's toilet activity and activate to automatically clean after use. The device connects to the sewer system and ensures efficient waste removal without the need for intervention from the owner. Additionally, the toilet has a large flushable storage capacity, making it ideal for multi-cat households. The Petgugu cat litter bowl is designed for use with water-soluble litters and offers a range of additional ... >>

The attractiveness of caring men 14.04.2024

The stereotype that women prefer "bad boys" has long been widespread. However, recent research conducted by British scientists from Monash University offers a new perspective on this issue. They looked at how women responded to men's emotional responsibility and willingness to help others. The study's findings could change our understanding of what makes men attractive to women. A study conducted by scientists from Monash University leads to new findings about men's attractiveness to women. In the experiment, women were shown photographs of men with brief stories about their behavior in various situations, including their reaction to an encounter with a homeless person. Some of the men ignored the homeless man, while others helped him, such as buying him food. A study found that men who showed empathy and kindness were more attractive to women compared to men who showed empathy and kindness. ... >>

Random news from the Archive Next generation visual processor Movidius Myriad 2 10.08.2014 In early 2014, Movidius introduced the Myriad-1, its first visual processor (VPU - Vision Processing Unit in the company's terminology). Google used this chip in the Project Tango smartphone, which aroused great public interest. Now Movidius has unveiled its new generation VPU Myriad-2, which will appear in commercial products next year. While the Myriad-1 was designed with the goal of getting VPU capabilities into the hands of developers as early as possible, the Myriad-2's main goal is to improve performance without sacrificing power efficiency. It is worth noting that the new chip is backward compatible with Myriad-1, so any existing code will run on it without any modifications, but much faster thanks to a number of deep Movidius hardware optimizations. The second generation VPU from Movidius uses a mixture of fixed-function hardware and programmable blocks, while the first generation relied entirely on programmable blocks. It is clear that simple small blocks that perform certain functions can significantly increase performance without increasing power consumption. In turn, more complex programmable blocks are usually less effective in solving simple problems. The company notes that Myriad-2 received 12 main cores, while the previous generation chip included 8 cores. In addition to the increase in the number of units, their operating frequency has been more than tripled: from 180 MHz to 600 MHz. The total computing performance of the chip reaches 2 Teraflops (a very theoretical figure, taking into account the operation of blocks with fixed functionality), while the power consumption is only 500 mW, so that Myriad-2 can be used in mobile devices. You can use the power of the Myriad 2 chip using the open API OpenCL. As the manufacturer notes, the main task of the VPU is to ensure that mobile devices take photos with a quality close to SLR cameras. It is impossible to use a large matrix and massive lenses in mobile devices, so all this should be replaced by computational photography technologies. The challenge is to reconstruct visual information using algorithms and additional data (multi-frame, second camera, statistics, and so on). There are millions of pixels on each frame, so you need a lot of computing power to process the data. However, when it comes to mobile devices, you should also think about power consumption. Other uses for the Myriad 2 could include 3D scanning, 3D modeling, 3D reconstruction, and so on - it's not for nothing that Google has used such a chip in its Tango visual smartphone. For example, such smartphones will be able to provide accurate measurements of surrounding objects based on photographs, which can be useful when buying furniture. VPUs can also be used in other systems where visual processing technologies are important: surveillance, car security, robotics and entertainment, that is, wherever there are cameras.

Other interesting news:

▪ Algae will help extract gold from hot springs

▪ Tablet with built-in DLP projector

▪ The ocean is destroying the ozone layer

▪ Low profile SSD H6201 from BIWIN

▪ Link found between food intake and body clock

News feed of science and technology, new electronics

Interesting materials of the Free Technical Library:

▪ section of the site for those who like to travel - tips for tourists. Article selection

▪ article Infectious diseases. Lecture notes

▪ article When and where did the Red Army and White Guards fight on the same side in the same uniform? Detailed answer

▪ article Working on a printing and die-cutting machine with a special device for hot stamping with gold and colorful foil. Standard instruction on labor protection

▪ article Theory and practice of a phase inverter. Encyclopedia of radio electronics and electrical engineering

▪ article Adjustable stabilizer 0,7-12 volts. Encyclopedia of radio electronics and electrical engineering

Leave your comment on this article:

All languages ​​of this page

Arabic	Hebrew	Polish
Bengali	Hindi	Portuguese
Chinese	Italian	Spanish
English	Japanese	Turkish
French	Korean	Ukrainian
German	Malay	Vietnamese

Home page | Library | Articles | Website map | Site Reviews

www.diagram.com.ua
2000-2024