|
Arabic
Bengali
Chinese
English
French
German
Hebrew
Hindi
Italian
Japanese
Korean
Malay
Polish
Portuguese
Spanish
Turkish
Ukrainian
Vietnamese|
ENCYCLOPEDIA OF RADIO ELECTRONICS AND ELECTRICAL ENGINEERING Receiver for centimeter waves. Encyclopedia of radio electronics and electrical engineering
Encyclopedia of radio electronics and electrical engineering / radio reception
On fig. 1 shows a diagram of this receiver. The first lamp is regenerative and detector; the second and third are low frequency amplifiers.
As a detector lamp, we took a shielded SO-95 lamp. It turned out to be the best of both ordinary three-electrode and shielded lamps currently existing and the most suitable for receiving such short waves. In the low-frequency amplifier in both stages there are UT-40 lamps. The receiver is assembled on a corner panel (see photo) with dimensions of 250 X 130 mm - vertical and 170 X 130 mm - horizontal part. The panels are made from dry 65mm plywood and then covered with black lacquer. A small socket (170 x 15 mm) is attached to the horizontal part, on which two rheostats and sockets for turning on telephone receivers are fixed. The rheostats have a resistance of XNUMX ohms and are used to regulate the incandescence of the low-frequency amplifier lamps. In order not to make the design of the receiver too cumbersome, the detector lamp filament rheostat is not mounted on the receiver panel, but together with a step-down power transformer and, therefore, is removed from the receiver. On the main horizontal panel are placed parts of the low frequency amplifier, and on the rear vertical panel is the detector lamp of the receiver. From the photographs it can be seen that the detector lamp is in a horizontal position and raised high above the low frequency amplifier. This arrangement of lamps was chosen in order to make the installation of the receiver easier. Power terminals are located on the vertical panel. Three of them are set high, almost at the lamp socket of the detector lamp. An alternating voltage is supplied to the two extreme terminals from the transformer through a rheostat to heat the filament of the detector lamp. The upper middle terminal energizes the shielding grid of the detector lamp. To the first lower terminal (when viewed from the reverse side of the vertical panel), plus the anode voltage is supplied, to the second - minus the anode voltage, to the third - plus the glow and to the fourth - minus the glow (see Fig. 3). We now turn to the manufacture of the main part of the receiver - the oscillatory circuit. Details It can be seen from the photographs and the diagram that the oscillatory circuit of the receiver is a deployed oscillatory circuit with a variable setting. Details of the oscillatory circuit of the receiver are shown in fig. 2.
The receiver is tuned to the transmitter wave by changing the length of the parts of the oscillatory circuit attached to the grid and the cathode of the detector lamp. In practice, tuning is carried out by greater or lesser insertion of brass rods into the brass tubes. Small ebonite handles are placed on the finished rods at one end (Fig. 2 cd). Chokes are included in all power wires: they prevent the penetration of high frequency vibrations into the amplifier, as well as into the batteries. Chokes Dr1, Dr2, Dr3, Dr4 and Dr5 are the same and have 12 turns of wire with a diameter of 1,5 mm. The chokes are made as follows: on a wooden stick with a diameter of 9 mm, a turn to turn of 13 turns is wound close to the turn. Then the throttle, without removing it from the stick, is stretched so that its length is 40 mm. After that, the throttle is removed from the stick. In the manufacture of chokes, it should be remembered that they are made from mounting wire, the pieces of which must be taken in such a way that they are enough for the choke, and the remaining ends of the wire could be attached to the corresponding parts of the circuit. When assembling the receiver, the inductors should be placed so that their first turns are at the lamp electrodes, i.e. so that the connecting wire between the inductor and the lamp electrode is as short as possible. The resistance r3 has 1,5 megohm. Lamp sockets are non-capacitive. All terminals and telephone jacks are mounted on ebonite bushings. Thus, none of the details of the receiver touches the tree. Low frequency transformers in the first stage have a ratio of 1:5, and in the second 1:4. Installation The oscillatory circuit is attached with the help of strips of 0,8 mm brass soldered to each of its halves at one end, which are then wrapped around the tube. A hole is drilled in the remaining ends of the brass strip, with the help of which the strip, together with the tube, is attached to the grid contact and to the cathode contact. In order for the structure to be rigid and the oscillatory circuit to be firmly fixed, the tube is attached to a vertical panel.
All connections are made with 1,5 mm copper wire, preferably silver plated. After the receiver is assembled, proceed to its establishment. They put the receiver at a distance of several meters from the transmitter, light the receiver lamps and, turning on the transmitter, tune the receiver to it. If no transmitter signals are detected during tuning, then the operating mode of the transmitter is changed by adjusting the incandescence of the generator lamps and the length of the Lecher systems located in the anode and generator grid. Having adjusted the receiver, we can start receiving over longer distances. This receiver received the work of the transmitter at a distance of up to 300 m. At the same time, at a distance of the receiver from the transmitter of 100 m, the audibility reached R = 6, and at 300 m - R = 2-3. The work on the transmitter was carried out with a key. The transmitter and receiver should be placed so that the vibrator and the deployed oscillatory circuit of the receiver are not parallel and so that the experimenters can see each other. Experimenting with the described transmitter and receiver was carried out in Moscow in an open area. The transmitter was installed outside on the wall of the house at a height of 2 m from the ground; food was supplied through the window of the house. The receiver was placed at a height of about 1,2 m from the ground. You should experiment with two or, even better, three. At the same time, one is located at the transmitter, and two are at the "movable" receiver. The operating mode of the receiver was supported by us as follows: the glow of the detector lamp is 1,3V; the voltage supplied to the anode of the detector lamp and low frequency lamps is 80 V, and the voltage supplied to the screening grid is 25-30 V.
Artificial leather for touch emulation
15.04.2024 Petgugu Global cat litter
15.04.2024 The attractiveness of caring men
14.04.2024
▪ A sleeping bag that will keep astronauts sighted ▪ Analog Devices Blackfin Digital Signal Processor ▪ In a few years, a person will have 12 times more electronics ▪ Programmable photonic quantum chip
▪ site section Lighting. Article selection ▪ article by Marlene Dietrich. Famous aphorisms ▪ article Which American woman married the president without changing her last name? Detailed answer ▪ article Engineer of the compressor station. Standard instruction on labor protection
Home page | Library | Articles | Website map | Site Reviews
www.diagram.com.ua |
See other articles Section 
Latest news of science and technology, new electronics:
All languages of this page