Powerful 13 8 volt power supply. Making a transceiver power supply

The task was: to make a power supply for the KEWOOD TS-850 HF transceiver instead of a failed switching power supply, which broke during a severe thunderstorm in the summer; the antenna was not turned off at that time and when turned on, the circuit breaker in the apartment panel was knocked out. Having read discussions on homemade power supplies on various forums, we came to the conclusion that we need to make a transformer homemade power supply, although it will not be very light in weight, but in any case it can be repaired at home, especially since we have a lot of different pieces of hardware in stock and it would be a sin not to use them.

The first question is: what is the maximum current it must be manufactured for? According to the passport data, the maximum current consumption of the TS-850 is 22 Amperes; in reality, it consumes less current. The output voltage for the transceiver is standard - 13.8 Volts.
We begin to select the appropriate transformer, its power should be approximately 13.8 V * 22 A = 303.6 W. If we carefully analyze the power characteristics, then the transformers of the TN and TPP series have a maximum power of 200 W, which means that we need to select two transformers and in total the rated power will be 400 W. At first glance, the transformer TPP-317, TPP-318, TPP-320 are suitable (we look first of all in terms of power and current) and if the windings are connected in parallel and in series, then the transformer TPP-320 is best suited in the amount of 2- x pieces.

To increase the reliability of the power supply at maximum current, it was decided to increase the number of output transistors, in addition to reducing the current passing through the output transistors (the current is divided by the number of transistors), accordingly, the heat generation on each switch is reduced, which is very important.

The design of the radiator with four transistors installed on it, in this case, transistors in the TO-3 package were used, in the original version it was planned to supply KT819G, but as a result of testing different power supply circuits, the stock of domestic transistors ran out and I had to buy imported ones - 2N3055, which are cheap , although more powerful semiconductors are available today. The power supply circuit of R. RAVETTI (I1RRT), during testing, in my opinion, it showed the best characteristics with the simplicity of the circuit.
The photo shows transistors installed on the radiator and wirewound equalizing resistors with a nominal value of approximately 0.1 Ohm. It is planned to install two such strips with a radiator, which will ultimately amount to 8 transistors connected in parallel. The circuit is assembled using wall-mounted installation, the housing is selected to the appropriate dimensions from the device 30.5x13.0x20.0 cm.

The Kenwood TS-850 HF transceiver is connected to a homemade transformer power supply; in receive mode, the transceiver consumes about 2 amperes, as can be seen from the dial ammeter.

In the photo, the current consumption of the Kenwood TS-850 HF transceiver from the power supply when transmitting in CW mode is 15 amperes (under load, the supply voltage is 13.6 volts - see the voltmeter scale reading to the left of the ammeter), in the photo on the right is the TPP-320 transformer.
This power supply can be used for FT-840, FT-850, FT-950, IC-718, IC 746pro, IC -756pro, TS-570, TS 590S and other similar transceivers.

The proposed power supply (Fig. 1) is designed to work with a powerful low-voltage load, for example, with VHF FM radio stations with an output power of about 50 W ("Alinco DR-130"). Its advantages are a low voltage drop across the rectifier diodes and the regulating transistor and the presence of short circuit protection.
Mains voltage through closed contacts of switch SA1. fuse FU1 and line filter C5-L1-L2-C6 are supplied to winding I of power transformer T1. From the secondary winding II T1, which is tapped from the middle, positive half-wave voltages are supplied through rectifier diodes VD2 and VD3 to the smoothing filter capacitor C9.

A linear stabilizer with a regulating element based on a field-effect transistor (FET) VT2 is connected to the filter. To control this transistor, a voltage of 2.5...3 V is required, so there is no need for a separate rectifier to power the DC control circuits, such as in. To increase the stabilization coefficient, the stabilizer uses an “adjustable zener diode” - the DA1 TL431 microcircuit (domestic analogue - KR142EN19). Transistor VT1 is a matching transistor, zener diode VD1 stabilizes the voltage in its base circuit. The output voltage of the stabilizer can be calculated using the approximate formula
The stabilizer works as follows. Let's say that when a load is connected, the output voltage decreases. Then the voltage at the midpoint of the divider R5-R6 decreases, the DA1 microcircuit (as a parallel stabilizer) consumes less current, and the voltage drop across its load (resistor R2) decreases. This resistor is in the emitter circuit of transistor VT2 and, since the voltage at its base is stabilized by the zener diode VD1. the transistor opens stronger, providing an increase in the voltage at the gate of the regulating transistor VT2. The latter opens more and compensates for the voltage drop at the output of the stabilizer. This ensures stabilization of the output voltage. The output voltage is set by resistor R6. Zener diode VD6. connected between the source and gate of VT2. serves to protect the PT from exceeding the permissible gate-source voltage and is a mandatory element in stabilizers with an input voltage of 15 V and above.
This power supply is a variant of the device described in. The same stabilizer with protection is used here, but the two-stage start-up of the power supply and the overvoltage protection circuit are excluded. The power supply has added a meter for output voltage and load current on a pointer device PA1 (microammeter head M2001 with a total deviation current of 100 μA), an additional resistor R7, a shunt RS1, an interference suppression capacitor C12 and a switch SA2 ("Voltage/current"). Since the operating temperature of the PT in this power supply is lighter, a PT of type IRF2505 is used in a TO-220 housing, which has a higher thermal resistance than IRF2505S.
The TN-60 transformer is found in two modifications: powered only from a 220 V network and with a combination of primary windings that allows the transformer to be connected to a network with voltages of 110.127. 220 and 237 V. The connection of the T1 windings in Fig. 1 is shown for a voltage of 237 V. This is done to reduce the no-load current T1, reduce the stray field and heat the transformer, and increase efficiency. In networks with reduced voltage (relative to 220 V), terminals 2 and 4 of the primary windings are connected to each other. Instead of the TN-60 transformer, you can use the TN-61.
To reduce the voltage drop under load, a midpoint rectifier circuit using Schottky diodes is used. the inclusion of T1 windings is optimized in order to evenly distribute the load on them. The power supply circuits are installed using a wire with a core cross-section of at least 1 mm2. Schottky diodes are installed without spacers on a small common radiator from an old computer monitor (aluminum plate), which, using the existing pins, is soldered into a circuit on which a set of C9 capacitors (4 pieces, 10,000 μF x 25 V) is placed. The RS1 shunt for measuring the load current is the “positive” wire that connects the bus on the printed circuit board from pins C9 to the load connection terminal.
Structurally, the power supply is very simple (Fig. 2). Its rear wall is a radiator, the front wall (panel) is a piece of duralumin 4 tAtA thick of the same length and width. The walls are fastened together with 4 07 mm steel studs. They have end holes with M4 threads. A 2 mm thick duralumin shelf according to the dimensions of the transformer is screwed to the lower pins (with 4 M4 screws). In the same way, a plate of one-sided o)jugated fiberglass with a thickness of 1.5 mm is attached. on which capacitors C9 and a radiator with diodes VD2, VD3 are mounted. On the front panel there are two pairs of output terminals (parallel), measuring head PA1. output voltage regulator R6, current/voltage switch SA2. fuse holder FU1 and power switch SA1. The power supply housing (U-shaped bracket) can be bent from mild steel or assembled from separate panels. The radiator for the PT (123x123x20 mm) was used ready-made, from the power supply of the old VHF radio station "Kama-R". The length of the fastening pins is 260 mm. but can be reduced to 200 mm with denser installation. Dimensions of the plates: duralumin for T1 - 117.5x90x2 mm, fiberglass - 117.5x80x1.5 mm.

Line filter coils L1. L2 are wound with a flat two-wire power cord on a ferrite rod (400NN...600NN) from the magnetic antenna of the radio receiver (until filling). Rod length - 160...180 mm, diameter - 8...10 mm. Capacitors of the K73-17 type, designed for an operating voltage of at least 500 V, are soldered to the terminals of the coils. The assembled filter is wrapped in a non-hygroscopic material, for example, electrical cardboard, on top of which a continuous screen of tinplate is made. The seams of the screen are soldered, the leads pass through insulating sleeves.
A stabilizer is good for everyone, but what happens if the load current exceeds the limit value for the control transistor, for example, due to a short circuit in the load? Obeying the described algorithm of work. VT2 will open completely, overheat, and quickly fail. For protection, you can use an optocoupler circuit. In a slightly modified form, this protection is presented in Fig. 1.
The parametric stabilizer on the VD4 zener diode provides a reference voltage of -6.2 V, voltage surges and noise are blocked by the capacitor SY. The output voltage of the stabilizer is compared with the reference voltage through the LED optocoupler chain VU1-VD5-R10. The output voltage of the stabilizer is higher than the reference voltage, therefore, it biases the junction of the diode VD5. locking him up. No current flows through the LED. When the output terminals of the stabilizer are short-circuited at the right terminal R10 according to the diagram, the negative voltage disappears, the reference voltage opens the diode VD5. The optocoupler LED lights up and the optocoupler phototriac is activated. which closes the gate and source of VT2. The regulating transistor closes, i.e. The output current of the stabilizer is limited. To return to operating mode after the protection has tripped, the power supply is turned off using SA1. eliminate the short circuit and turn it on again. In this case, the protection circuit returns to standby mode.
The use of such stabilizers with a low voltage drop across the DC makes it unnecessary to protect the powered equipment from excess voltage resulting from breakdown of the control transistor. In this case, the output voltage increases by only 0.5...1 V, which is usually within the tolerance standards for most equipment.

Most of the power supply elements (circled in dotted lines in Fig. 1) are placed on a printed circuit board measuring 52x55 mm. the drawing of which is shown in Fig. 3, and the location of the parts on the board is shown in Fig. 4. The board is made of double-sided foil fiberglass with a thickness of 1... 1.5 mm. The foil on the bottom side of the board is connected to the negative output bus of the stabilizer ("grounded" in Fig. 1) with a separate wire. The free leads of the VU1 optocoupler do not need to be soldered anywhere. There are holes marked on the board where the parts are soldered, but installation can be done from above, from the side of the printed conductors, without drilling holes. In this case, the board drawing corresponds to Fig. 4. A drawing of the board on which the heat sink with diodes and filter capacitors are located is shown in Fig. 5.
Before assembling the power supply, be sure to check the ratings of all parts and their serviceability. Connections
inside the power supply they are made with thick wires of minimal length. In parallel with all oxide capacitors, ceramic capacitors with a capacity of 0.1...0.22 μF are soldered directly to their terminals.
The current meter can be calibrated by connecting an adjustable load to the output terminals of the power supply unit in series with an ammeter for a current of 2...5 A. Having set the current on the ammeter, for example, 2 A, we select such a length of wire (shunt), twisting a loop from it so that the needle deflects PA1 was 20 divisions (on a scale of 100).

We move SA2 to another position, connect a control voltmeter to the output of the power supply, select resistance R7 (instead, you can turn on a trimming resistor with a resistance of at least 220 kOhm), we ensure that the readings of PA1 coincide with the readings of the voltmeter.
When working with radio transmitting equipment, interference to stabilizer parts and incoming and outgoing wires should be avoided. To do this, a filter similar to the mains filter should be turned on at the output terminals of the power supply unit (Fig. 1), with the only difference being that the coils should be wound on a ferrite ring or ferrite tube, used in old monitors and foreign-made TVs, and contain only 2-3 a turn of insulated wire with a large cross-section, and capacitors can be taken with a lower operating voltage.
Literature
1. V. Nechaev. Powerful voltage stabilizer module based on a field-effect transistor. - Radio. 2005. No. 2, P. 30.
2. Stabilizer with very low voltage drop.
3. V. Besedin. Defending ourselves... - Radiomir, 2008. No. 3. C.12-
4. Precision filament stabilizer. -klausmobile.narod.ru/appnoIes/an_11_fetreg_r.htm

V. BESEDIN, Tyumen.

Power supply 13.8V 25-30A for a modern HF transceiver

In recent years, more and more radio amateurs in the CIS have been using foreign-made equipment to operate on the air. To power most of the most common models of ICOM, KENWOOD, YAESU transceivers, an external power supply is required that meets a number of important technical requirements. According to the operating instructions for the transceivers, it must have an output voltage of 13.8 V at a load current of up to 25-30 A. The output voltage ripple range is no more than 100 mV. Under no circumstances should the power supply be a source of high-frequency interference. The stabilizer must have a reliable protection system against short circuits and against the appearance of increased voltage at the output, operating even in an emergency situation, for example, in the event of a breakdown of the main control element. The described design fully meets the specified requirements, in addition, it is simple and built on an accessible element base. The main technical characteristics are as follows:

Output voltage, V 13.8
Maximum load current, A 25 (30)
Output voltage ripple range, no more than mV 20
Efficiency at current 25 (30) A not less, % 60

The power supply is built according to a traditional design with a power transformer operating at a network frequency of 50 Hz. A unit for limiting the inrush current is included in the circuit of the primary winding of the transformer. This is done because a very large filter capacitance, 110,000 μF, is installed at the output of the rectifier bridge, which represents an almost short-circuited circuit at the moment the mains voltage is applied. The charge current is limited by R1. After about 0.7 seconds, relay K1 is activated and its contacts close a limiting resistor, which subsequently does not affect the operation of the circuit. The delay is determined by the time constant R4C3. An output voltage stabilizer is assembled on transistors VT10, VT9, VT3-VT8. When developing it, the circuit was taken as a basis, which has a number of useful properties. First, the collector terminals of the power transistors are connected to the ground wire. Therefore, transistors can be mounted on a radiator without insulating gaskets. Secondly, it implements a short circuit protection system with a reverse fall-off characteristic, Fig. 2. Consequently, the short circuit current will be several times less than the maximum. The stabilization factor is more than 1000. The minimum voltage difference between input and output at a current of 25 (30) A is 1.5 V. The output voltage is determined by the zener diode VD6, and will be approximately 0.6 V greater than its stabilization voltage. The current protection threshold is determined by resistor R16. As its rating increases, the operating current decreases. The magnitude of the short circuit current depends on the ratio of resistors R5 and R17. The larger R5, the lower the short-circuit current. However, it is not worth trying to significantly increase the rating of R5, since the initial start of the stabilizer is carried out through the same resistor, which can become unstable at reduced network voltage. Capacitor C5 prevents self-excitation of the stabilizer at high frequencies. The emitter circuit of the power transistors includes equalizing resistors of 0.2 Ohm for the 25-amp version of the power supply, or 0.15 Ohm for the 30-amp. The voltage drop across one of them is used to measure the output current. An emergency protection unit is assembled on transistor VT11 and thyristor VS1. It is designed to prevent high voltage from reaching the output in the event of a breakdown of the control transistors. Its diagram is borrowed from. The operating principle is very simple. The voltage at the emitter VT11 is stabilized by a zener diode VD7, and at the base it is proportional to the output. If a voltage greater than 16.5 V appears at the output, transistor VT11 will open, and its collector current will open thyristor VS1, which will bypass the output and cause fuse F3 to blow. The response threshold is determined by the ratio of resistors R22 and R23. To power the M1 fan, a separate stabilizer is used, based on transistor VT1. This is done so that in the event of a short circuit at the output or after the emergency protection system is triggered, the fan does not stop. An alarm circuit is assembled on transistor VT2. When there is a short circuit at the output or after fuse F3 has blown, the voltage drop between the input and output of the stabilizer becomes more than 13 V, the current through the zener diode VD5 opens the transistor VT2 and the buzzer BF1 emits a sound signal.

A few words about the element base. Transformer T1 must have an overall power of at least 450 (540) W and produce an alternating voltage of 18 V on the secondary winding at a current of 25 (30) A. Conclusions from the primary winding are made at points 210, 220, 230, 240 V and serve to optimize the efficiency of the unit depending on the network voltage at the specific location of operation. Limiting resistor R1 is wire-wound, with a power of 10 W. The rectifier bridge VD1 must be designed for a current flow of at least 50 A, otherwise, when the emergency protection system is triggered, it will blow out before fuse F3. Capacitance C1 consists of five 22000 μF 35 V capacitors connected in parallel. At resistance R16, at maximum load current, the power dissipates about 20 W; it consists of 8-12 resistors C2-23-2W 150 Ohm connected in parallel. The exact number is selected when setting up short circuit protection. To indicate the value of the output voltage PV1 and the load current PA1, measuring heads with a current deflection of the arrow to the last scale division of 1 mA are used. Fan M1 must have an operating voltage of 12V. These are widely used for cooling processors in personal computers. Relay K1 Relpol RM85-2011-35-1012 has an operating winding voltage of 12V and a contact current of 16A at a voltage of 250V. It can be replaced by another with similar parameters. The selection of powerful transistors should be approached very carefully, since a circuit with parallel connection has one unpleasant feature. If during operation, due to some reason, one of the parallel-connected transistors breaks down, this will lead to immediate failure of all the others. Before installation, each transistor must be checked with a tester. Both transitions should ring in the forward direction, and in the opposite direction, the deviation of the ohmmeter needle set to the x10 Ω limit should not be noticeable to the eye. If this condition is not met, the transistor is of poor quality and may fail at any time. The exception is transistor VT9. It is composite and inside the case the emitter junctions are shunted with resistors, the first is 5K, the second is 150 Ohms. See fig. 2.

When calling in the opposite direction, the ohmmeter will show their presence. Most transistors can be replaced with domestic analogues, although with some deterioration in performance. Analogous to BD236-KT816, 2N3055-KT819BM (necessarily in a metal case) or better KT8101, VS547-KT503, VS557-KT502, TIP127-KT825. At first glance, it may seem that the use of six transistors as the main control element is unnecessary, and you can get by with two or three. After all, the maximum permissible collector current of 2N3055 is 15 amperes. A 6x15=90 A! Why such a reserve? This is done because the static current transfer coefficient of the transistor strongly depends on the magnitude of the collector current. If at a current of 0.3-0.5 A its value is 30-70, then at 5-6 A it is already 15-35. And at 12-15 A - no more than 3-5. Which can lead to a significant increase in ripple at the output of the power supply at a load current close to the maximum, as well as a sharp increase in thermal power dissipated by transistor VT9 and resistance R16. Therefore, in this circuit, it is not recommended to remove a current of more than 5A from one 2N3055 transistor. The same applies to KT819GM, KT8101. The number of transistors can be reduced to 4 by using more powerful devices, for example 2N5885, 2N5886. But they are much more expensive and more scarce. Thyristor VS1, like the rectifier bridge, must be designed for a current flow of at least 50A.

In the design of the power supply, it is necessary to take into account several important points. Diode bridge VD1, transistors VT3-VT8, VT9 must be installed on a radiator with a total area sufficient to dissipate thermal power of 250W. In the author's design, it consists of two parts, serving as the side walls of the body, and having an effective area of 1800 cm each. Transistor VT9 is installed through an insulating heat-conducting gasket. Installation of high-current circuits must be done with a wire with a cross-section of at least 5 mm. The ground and positive points of the stabilizer should be points, not lines. Failure to comply with this rule can lead to an increase in output voltage ripple and even to self-excitation of the stabilizer. One of the options that meets this requirement is shown in Fig. 4.

Five capacitors forming capacitance C1 and capacitor C6 are located on the printed circuit board in a circle. The area formed in the central part serves as a positive bus, and the sector connected to the minus of capacitor C6 serves as a negative bus. The lower terminal of resistor R16, the emitter VT10, the lower terminal of resistor R19 are connected to the central pad with separate wires. (R16 - wire with a cross-section of at least 0.75 mm) The right terminal R17 according to the diagram, anode VD6, collectors VT3-VT8 are connected to minus C6, each also with a separate wire. Capacitor C5 is soldered directly to the terminals of transistor VT9 or located in close proximity to it. Compliance with the point grounding rule for elements of the fan supply voltage stabilizer, inrush current limiter, and alarm device is not necessary and their design can be arbitrary. The emergency protection device is assembled on a separate board and is attached directly to the output terminals of the power supply from the inside of the case.

Before you begin setting up, you should pay attention to the fact that the described power supply is a fairly powerful electrical device, when working with which caution and strict adherence to safety regulations are required. First of all, you should not rush to immediately connect the assembled unit to a 220V network; first you need to check the functionality of the main components of the circuit. To do this, set the slider of the variable resistor R6 to the rightmost position according to the diagram, and the resistor R20 to the top. Of the resistors forming R16, only one should be installed at 150 Ohms. The emergency protection device must be temporarily disabled by unsoldering it from the rest of the circuit. Next, apply a voltage of 25V to capacitor C1 from a laboratory power supply with a short-circuit protection current of 0.5-1 A. After about 0.7 seconds, relay K1 should operate, the fan should turn on, and a voltage of 13.8 V should appear at the output. The value of the output voltage can be changed by selecting a zener diode VD6. Check the voltage on the fan motor, it should be approximately 12.2 V. After this, you need to calibrate the voltage meter. Connect a reference voltmeter, preferably digital, to the output of the power supply, and by adjusting R20 set the arrow of the PV1 device to the division corresponding to the readings of the reference voltmeter. To configure the emergency protection device, you need to apply a voltage of 10-12 V to it from a laboratory regulated power source through a 10-20 Ohm 2 W resistor. (In this case, it must be disconnected from the rest of the circuit!) Turn on the voltmeter in parallel with the thyristor VS1. Next, gradually increase the voltage and note the last reading of the voltmeter, after which its readings will sharply drop to a value of 0.7 V (thyristor has opened). By selecting the value of R23, set the response threshold at 16.5 V (the maximum permissible supply voltage of the transceiver according to the operating instructions). After this, connect the emergency protection device to the rest of the circuit. Now you can turn on the power supply to a 220 V network. Next, you should configure the short-circuit protection circuit. To do this, connect a powerful rheostat with a resistance of 10-15 Ohms to the output of the power supply through an ammeter for a current of 25-30 A. Smoothly reducing the resistance of the rheostat from the maximum value to zero, remove the load characteristic. It should have the form shown in Figure 2, but with a bend at a load current of 3-5 A. When the rheostat resistance is close to zero, an alarm sound alarm should sound. Next, you should solder in one by one the remaining resistors (150 Ohms each) that make up the resistance R16, each time checking the value of the maximum current until its value is 26-27 A for the 25-amp version or 31-32A for the 30-amp. After setting the short-circuit protection, it is necessary to calibrate the output current measuring device. To do this, set the load current to 15-20 A using a rheostat and adjust the resistor R6 to achieve the same readings from the dial gauge PA1 and the reference ammeter. At this point, setting up the power supply can be considered complete and you can begin thermal testing. To do this, you need to completely assemble the device, use a rheostat to set the output current to 15-20A and leave it on for several hours. Then make sure that nothing has failed in the unit, and the temperature of the elements does not exceed 60-70 C. Now you can connect the unit to the transceiver and carry out a final check under real operating conditions. It should also be remembered that the power supply includes an automatic control system. It may be affected by high-frequency interference that occurs when the transceiver transmitter operates with an antenna-feeder path that has a large SWR value or asymmetry current. Therefore, it would be useful to make at least the simplest protective choke by winding 6-10 turns of the cable connecting the power supply to the transceiver onto a ferrite ring with a permeability of 600-3000 of the corresponding diameter.