Power supply for antenna amplifier for TV. Power supply for antenna. The main function of a TV antenna amplifier

Power supplies, or PSUs, are included with antennas with amplifiers to improve the signal. Power supplies can be used in signal amplifiers for TV, mobile and satellite communications, as well as the Internet. A power supply is required when using a Wi-Fi adapter, which is also an antenna. There is a separate class of devices that is used for the needs of the defense industry. Wherever radio waves are used, there are receiving antennas, many of which require power supplies.

The most questions are raised by power supplies operating from conventional 220 W networks. These elements are built into general device antennas or located separately and connected through a specific port. If we're talking about about built-in devices, the design uses a transformerless circuit. Here voltage stabilization occurs due to latitudinal pulse modulations. The power supplies are plugged into a regular electrical outlet with a voltage of 220 volts and are designed for an average power of 10 W, which provides power to the antenna. Thus, these elements occupy a fairly small volume, but if they break, they disable the entire reception system.

External devices are usually designed so that if they break down, a certain signal level is still maintained. Although one cannot count on this signal being good. Another advantage of external antenna power supplies is that they are easier to replace.

The main circuit is built on a transformer, and output voltage power supply is stabilized parametrically. Standard values ​​for output voltages are 24, 18, 12 and 5 W. The required value will be determined based on technical parameters antennas. Using a transformer allows you to achieve more stable operation in conditions electrical networks, which are characterized by power surges, for example, in a country house or suburban area.

Principle of operation

Any household power supplies, as a rule, are manufactured by manufacturers at minimal cost, but what can be said about their reliability. This applies to both cheaper Chinese and expensive European ones too. Often these elements fail very quickly, which is explained by the round-the-clock operation of this equipment. In addition, due to constant overheating, the radio components of the device constantly operate under increased load.

Therefore, questions about the design, repair and replacement of various parts of this equipment are so often found on the Internet. In order to understand the principle of operation of the antenna and how to connect the antenna cable, consider one of the diagrams.

The circuit of this device consists of several main elements:

• a transformer, the design of which includes a current breakdown fuse T1;
• voltage stabilizer DA1;
• rectifier VD1-VD4;
• filters for low C5 and high C6 frequencies;
• voltage indicator 12 V HL1.

Please note that this power supply circuit implies an unregulated design designed to operate an antenna amplifier to regulate the level of signal amplification through an adjustable power supply. The design of the latter is complemented by a variable resistor, which makes it possible to change the supply voltage supplied to the antenna amplifier.

How to properly connect the power supply

The antenna amplifier is already built into the active antenna, but not into the passive one. To solve this problem, a power supply is connected. To connect the power supply cable to the antenna, first of all, you will need to mount the antenna cable with a plug specially designed for this purpose. Let's look at how this is done using the Delta PSU as an example.

To do this, the cable is first prepared, which means stripping it: a thin circular cut at a distance of 15 mm from the edge of the cable.

The main condition when performing this work is accuracy; try not to damage the fairly thin hairs of the shielded braid located under the outer layer of insulation. Next, the mentioned screen hairs are carefully bent back, and the strip of foil located near them is removed.

The next stage of cable preparation implies that you should make another circular cut, but this time stepping back from the curved edge of the braid by 5-7 mm, which will help remove the internal insulator. Next, the wire prepared for installation is inserted under the corresponding fasteners in the Delta PSU box and tightened with screws.

Note! When a cable is connected, its metal braid must be in contact with the design of the Delta PSU housing - a tinned area. Otherwise, no power will be supplied to the antenna. It should also be taken into account that the cable braid should not touch the central core of the cable. If this happens, the power supply indicator will not work, as a short circuit will occur.

On a note. When the antenna amplifier power supply is correctly connected to the antenna cable, after making the appropriate settings, the TV will begin to display a much larger range of channels.

Malfunctions

There are a number of the most common malfunctions of the antenna power supply:

• failure of a block design element such as a transformer;
• stabilizer failure;
• device filter malfunction.

Also, often the breakdown of the power supply is associated with the failure of the fuse, which, as a rule, causes an overload of the secondary circuit or voltage surges. To identify this problem if the power supply is faulty, it is enough to measure the resistance at the plug of the device. Note that the absence of voltage may also indicate a break in the primary transformer winding.

A malfunction of the stabilizer causes a decrease or increase in the supply voltage of the antenna amplifier, which often leads to its breakdown (complete failure). To identify the problem, the voltage at the power supply output is measured.

Filter capacitors also play a significant role in the operation of the power supply, the failure of which can cause serious image interference when watching TV. As a rule, such a breakdown has characteristic features: Interference in the form of fairly wide horizontal black bars that slowly move across the TV screen.

Attention! Like any equipment, the power supply of an antenna amplifier has a limited service life. To increase it, do not forget to turn off the device if you leave home for a long time.

Repair of antenna amplifier power supply

Most owners of television antennas with an amplifier, if an element of the device such as a power supply breaks down, immediately rush to the point of sale of these devices to buy a new one. Nevertheless, it is quite simple to cope with the problem that has arisen and “reanimate” a non-working power supply. The main thing is to determine where the breakdown occurred.

Signs of PSU malfunction and initial check

The first sign indicating a malfunction of the power supply for the antenna amplifier is the absence of an indication on the device body or the LED periodically going out.

The initial test involves measuring the transformer primary winding with a tester. Note that the range of measurement results must correspond to such indicators - 2.5-2.7 kOhm. The absence of a circuit clearly indicates possible malfunctions such as a failure of the transformer or a break in the wire connecting the transformer and the plug of the device.

The next step is to check the resistance indicators of such a structural element as the antenna plug, to the contacts of which the power cable is soldered (the device should indicate the absence of a short circuit).

Important! Sometimes it is enough just to ring the cable to the power supply. The malfunction may be a simple wire break.

Features of disassembling the power supply and subsequent testing

To disassemble the unit, unscrew the screws holding the housing cover, after which it must be removed. Next, the device board is dismantled by unscrewing the screw.

Please pay attention! Some power supplies use special clamps to hold the board, which makes disassembling the power supply easier.

Checking diodes and stabilizers

To assess the performance of the unit, check the diodes (D1-D4).

Important to consider! The resistance indicators of serviceable diodes correspond to the following figures - 450-650 Ohms, otherwise - indefinitely.

Checking the stabilizer implies that the microcircuit is working. To do this, tester probes are connected to the entry points. Normal values ​​for the voltage supplying the stabilizer microcircuit should be within 21 V. Next, the output voltage is checked (as a rule, in this case the norm is zero values). The occurrence of jumps (changes in indicators from 0 to 18 V) indicates a malfunction of the stabilizer.

Dismantling and replacing the stabilizer circuit

If such a design element of the power supply unit as a voltage stabilizer is faulty, it should be properly dismantled (unsoldering the microcircuit marked 78L12). To replace the failed element, you need to select a similar one, make the correct connections and solder it. After all the manipulations, the power supply voltage at the output is checked: normal indicators– 12.1 V. Essentially, this is where the repair of the antenna power supply ends.

Other ways to connect the power supply

Using a power supply, you can solve the problem of how to connect the antenna cable to cable television through the wire already included in the apartment. Typically a crab is used for branching. But quite often, with a weak initial signal, the use of crab leads to the fact that the image quality drops significantly, or the TV begins to pick up fewer channels than before.

This problem can be solved if you connect not just via cable, but using a signal amplifier and power supply. Using this circuit, you can connect a power supply and make the television signal reception more stable.

Video

There are places where the television signal arrives in very low quality. In such cases, you have to use an external antenna, on the vibrator of which the antenna amplifier is located. It allows you to strengthen the signal even at a distance of 100 km from the tower.

Widely used amplifiers are SWA amplifiers. They have low price and provide sufficient reliability. They have different gains and are designed for different ranges of channels. In the decimeter range, the gain is 34-43 dB and 10-15 dB in the meter range. In the photo below you can see the amplifier model SWA-555/LUX.

The SWA signal amplifier operates from a constant 12 V power supply. There is a circuit that allows voltage to be supplied to the amplifier via a coaxial cable along with the signal. On the market you can find an adapter that is also a power supply that solves the problem. It is shown in the photo below.

Connecting the adapter does not require any skills. We insert the wire that goes to the TV into one coaxial cable, and the antenna wire into the other. The adapter is installed into the outlet. It is not possible to mix up the wires, since there are different connectors at their ends.

By opening the power supply with the adapter, you can find a power transformer, simple and electrolytic capacitors, 4 diodes, an inductor, and a microcircuit that acts as a voltage stabilizer.

Everything except the transformer is located on the printed circuit board.

Electrical circuit diagram of the power supply with adapter

The adapter shown in the photo above is assembled according to the classical scheme. AC voltage The 220 V network is supplied to T1 (transformer), which in turn reduces it to 12 V - 15 V. VD1-VD4 (diode bridge) will perform the function of a voltage rectifier. To smooth out ripples, capacitor C1 is used. After which a constant voltage is obtained, the value of which is about 16 V. Then it goes to DA1 (integrated stabilizer).

An LC filter is made on elements C3, L1. It is installed at the receiver input. It prevents loss DC voltage and loss of video signal.

L1 (choke) prevents the high-frequency signal from flowing into the power supply circuit. At the same time, direct current flows freely to the central core of the TV cable, which comes from the amplifier. C3 (capacitor) prevents DC current from flowing from the power source to the TV input. There is no signal loss in this case.

For self-made power supply, parts can be used various types. Any transformer can be used with an output voltage of 15-18 V. This is due to the fact that the antenna amplifier does not exceed a current consumption of more than 2 W and 150 mA. As a choke, you can use a piece of dielectric, for example textolite, the width of which is 5 mm. From 25 to 30 turns of enameled copper wire are wound on it.

Disadvantages of the presented design of the power supply with adapter

One of the disadvantages is the presence of a section that does not have a screen on the central core of the television cable. This section is located at the soldering point with printed circuit board. When operating equipment such as a vacuum cleaner, this may cause interference to the video signal. This can be avoided by installing an additional screen.

Making your own adapter

If you need an adapter - an adapter that has wide technical capabilities, you can make it at home from a crab antenna splitter. To power the amplifier and additionally connect several TVs to the antenna, the crab circuit will have to be supplemented with 3 parts.

Design and diagram of the crab

The TV crab is a metal case with F connectors. High-frequency transformers for the TV signal splitter are wired inside it. They are located on the central terminals. The high-frequency transformer looks like a tube or ring made of ferrite. It has a magnetic permeability of 600-2000. Turns of enameled wire are wound on top, the diameter of which is 0.2 mm–0.3 mm. They are located evenly around the entire circumference. The number of such turns can reach from 1 to 10.

The photo shows a crab. The back cover has been removed. As you can see, the ferrite transformers are wired in order to connect 3 TVs. It was made according to the principle electrical diagram which is given below.

All crabs are made according to this pattern. It may have some deviations - installed chokes, resistors, filtering, decoupling capacitors.

How to make your own adapter
for supplying supply voltage to the antenna amplifier

In order to make an adapter designed to supply voltage to the antenna amplifier, I did not install a connector under the power supply. I decided to use one connector to connect the F-plug. To do this, it was necessary to remove one transformer. The number of connected TVs has decreased to two.

As a result, the concept has undergone changes.

Before using the adapter for its intended purpose, you should install the LC filter in the crab. The crab body is made of duralumin, so I made a brass terminal. It was secured to the body using a screw and a shaped nut.

As a result, the scheme changed slightly. Transformer T1 remained in its place, 2 capacitors and a choke were added.

To match the circuit, it is advisable to install a 150 Ohm resistor between the output pins XW3 and XW2. The adapter can be installed in any convenient place. Both at the cable entrance to the apartment and near the TV.

If you only use one TV, T1 can be removed from the circuit. Solder the right pin C1 (capacitor) to the central pin of connector XW3 or XW2. The cable will be connected to the connector to which the capacitor will be soldered.

Connecting the power supply to the adapter

I previously wrote that I want to connect the cable via the F connector. Therefore, from the double wire that came from the power supply, I made an adapter to a coaxial cable.

Hi all

I would like to leave a small note here regarding the exclusion of the external power supply for the amplifier of a conventional Polish antenna, subject to the use of a set-top box for reception digital TV broadcast in standard DVB-T2 (for now).

Or, when using another device, for example, a TV with a built-in digital TV receiver that supports supplying a special active antenna with an amplifier to the antenna input.

The essence of the story. When I was looking at the settings of the set-top box for signal reception digital television in standard DVB-T / DVB-T2, then I found next to the manual and auto-tuning options an option to turn on the antenna power. The first thought is whether it will be possible to power the antenna amplifier with this voltage S.W.A., on the Polish antenna" grate"?

And I decided to try...

The experiment was carried out using an attachment for receiving digital TV - Rolsen RDB-502N, inside the device there is a board with something like this: YJ--DVB-78316M+MXL603, but this is not the whole name, I can’t remember completely exactly, nor the revision. Since I don’t have access to the device now, I won’t be able to look more accurately.

The point is not this, but the fact that before I measured the voltage at the antenna connector of the set-top box, I was counting on 12 volts. But no, I broke off, which was confirmed when disassembling the device - built-in pulse block power supply, supplies the set-top box with voltage only 5 volts. And to be precise - 5.2 volts, if my Chinese cheap multimeter didn’t lie.

There is short circuit protection: in the event of a short circuit in the antenna connector, nothing bad will happen - the set-top box processor immediately turns off the power, and the corresponding option in the set-top box settings is disabled. The field-effect transistor does not burn out from this, and I looked at how it works on the diagram: there is a second transistor, some kind of circuit feedback, and all this goes to the processor leg, to which the radiator is glued. Its name is on the board's marking; I did not peel off the heatsink itself.

This is approximately the voltage that was on the antenna connector... 5.2 volts Total

The point is that for this console there are room active antennas with an amplifier. True, I have never seen such antennas before. But they are

In this case, the set-top box is used in conjunction with an antenna " Delta"to which the amplifier is connected from Polish antenna "lattice", and if my memory serves me right, then it is installed there SWA-2000. Or SWA-49, I don’t remember exactly how I’ll get to the antenna - I’ll add to the article. No more than a digital repeater ~100 kilometers (the farthest repeater is the first multiplex).

So, it seems to me that the antenna native to this amplifier has better characteristics.

But in my case, using an antenna delta(the other one was not available, the mustache is connected too) - it also turns out to be more or less stable to watch the first and second multiplex, with the parameters " force"/"quality" - ~84% /~72% respectively. Provided that the antenna is installed at the height of the third floor.

And this one standard amplifier" S.W.A." - has a supply voltage 12 volts, from an external power supply, which in my opinion is quite " nasty", since it gets quite hot, which I don’t like, and I have to turn it on every time...

By the way - at idle, the power supply produces as much as about 19 volts, and when the connected amplifier is operating, the voltage drops to 11.6 volts,

Conclusion - the amplifier operates normally from 11.6 volts. But such a set-top box produces more than half as much - 5.2 volts, but, theoretically, this should not be enough, and the gain, with such power supply to the amplifier, should drop.

To find out, I, without any hope, dismantled the cable, turned on the antenna supply voltage in the amplifier settings, and quickly threw the cable onto the connector of the included set-top box ( accidentally shorting it a couple of times, anew o including power in settings), and everything worked!

However, the channel image ( Muz TV) disintegrated quite often, and force/quality were on the level 83% And 69% respectively. That is, the quality parameter fell, albeit not much, but there was no longer stability.

Then I got a little depressed and decided to order from China one of such boost voltage converters to five volts do 12 volts, but only when the set-top box was running, and began to prepare a board for connecting it.

Since I did not find a diagram on the Internet ( please send it if you have it) set-top boxes for receiving digital TV - Rolsen RDB-502N, then I had to figure it out myself.

Sorry for the lack of photos this time - I’m writing from old memory.

There, in the upper right corner, there is a radio module on the board, it is covered with an iron shield.

His internal structure I became not interested when I studied it roughly ( iron cover of the module screen on top - opens without problems), and found field-effect transistor, which is responsible for supplying power to the antenna connector when it is open.

I unsoldered it, and decided, just in case there were no problems, to solder only two legs of the transistor onto the board, and connected the third leg to the common wire, through a resistor 20 kOhm. There is such a resistor on this track going to the antenna, from which I disconnected the transistor, and to which I was going to connect the output from the boost converter.

Not directly, of course, from the converter to power the antenna, but through a formal filter, which I built using surface mounting, connecting a capacitor to the track going to the antenna 100 nF (marking 104), connecting its second leg to the ground, then connecting some small coil from an old but imported TV, which has an unknown inductance, because there is nothing to measure.

And on the other side of the coil, I again connected it all to a common wire, through the same non-polar capacitor to 100 nanofarads.

It may be excessive and perverse, but I'd rather be safe than sorry. There is no need for unnecessary interference, and the converter definitely creates it. He's impulsive.

So I thought that the output from the converter to the filter coil ( this is safe, nothing should burn from 12 volts, short circuit detection goes to the field operator, and 12 volts should not go to the processor of the set-top box. But it is not exactly. There’s just no diagram, but I spent a long time running a probe around the board and couldn’t find any connections to the antenna power path outside the receiving unit).

The converter will receive power from the field worker. The only thing I'm afraid of is going into a short circuit when the converter starts. We need an experiment.

And the common wire is the common wire.

Possible question: why do you need a converter, and why make 12 volts out of 5, if you can simply disassemble the power supply, and install a transformer from it inside the body of the set-top box, and supply 12 volts from it to the antenna connector, fortunately there is a lot of space inside the set-top box?

Yes, indeed, there is a lot of free space inside the console, and at least 8 of these transformers will fit in there, and the lid should close, and everything will work.

But you can’t do this, it’s stupid and a fire hazard - this transformer will work and heat up 24/7, even in standby mode. What for? Who will turn it off? ( if you are perverted like this, electricity bills are not critical, and you are not afraid of the increased possibility of burning down your home - do not forget to at least unsolder the field switch, otherwise, first, the 12 volt attachment will burn out)

However, there is an option to use some kind of relay or coil with a reed switch, with galvanic isolation (otherwise he'll kill the fucker ), which can be connected to the field device, so that either when the antenna power option is turned off, or in standby mode, the antenna power is turned off.

By the way, if you connect the relay coil to the line 5 volts- the meaning of this perverted idea will disappear, since 5 volts it's always there, it's the only food, it's duty... I think you get my point.

There are two more disadvantages if you bomb the transformer through the relay. First, there is no protection against short circuits in the antenna - which is obviously dangerous. And secondly, most likely, you will not find a relay that will not trigger short circuit protection with its coil. This can be circumvented by throwing in another more powerful field worker, but this is all a perversion.

It's better to try using a boost converter. The advantage of this approach will be the relative elegance of the solution, and the ability to adjust the voltage both higher and lower 12 volts- almost everything DC-DC converters have a voltage regulator. But naturally, higher 12 volts Powering the amplifier is not necessary and will lead to its failure.

In my case, everything happened even more interesting! Later, I tried to reduce the voltage by connecting a variable resistor of several kOhm, fortunately, the amplifier's current consumption is small, and the resistor should not have burned out. Nothing happened to the resistor, but when I started to rotate it while the console was running, when the voltage dropped up to 5 volts, I hardly noticed any deterioration strength/quality!

What happens, it is still possible to power the antenna amplifier from the set-top box without any converters, without deteriorating the reception quality and without unnecessary decoding errors - the image breaking up into cubes? Yoshka's meat, and I have already prepared everything for connecting something that has not yet been ordered from AliExpress boost converter...

Then I connected the leg back to that track, albeit through a filter - I did not remove it, I only removed the previously soldered resistor on 20 kOhm, since it is not needed yet, it already exists. Next, I unsoldered the power supply wire from the small board with the antenna connector, pulled out the board itself, removed the coil and capacitor that goes to the central core, and soldered the board back. Well, pushing the cable further, unscrewing and completely removing the clamping square nut, I passed its central core there, soldering it directly to the central contact of the connector in order to avoid unnecessary signal loss, then twisted and pressed the braid back to where it was. It turned out that the signal from the central core of the cable immediately went to the set-top box, without any matching coils or capacitors.

I turned on the whole thing - and everything works great, no worse than from 12 volts from the power supply!

And the first time I hooked the cable directly to the connector" on the snot", apparently because snot and I got such an unsatisfactory result...

Now, the set-top box works without a power supply, isn’t that good?

Conclusion: you can try to power the antenna amplifier directly from the set-top box, and even if there is 5 volts there, everything will work - tested!

I've seen reviews online that it doesn't work at 5 volts, but that's a lie.

However, not all amplifier models will operate in this mode, and the issue of increasing the voltage is relevant. When I get to the antenna, I'll write down the amplifier model. 100 kilometers from the third floor with five volts of amplifier power to receive a digital TV signal - really. And if I used this amplifier with its native “grid,” it would be a hundred pounds, and visibility would be far from direct.

Please note that in nature there may be different devices for receiving digital TV that support 12 volts at the antenna input, and there are others without this function at all. Read the instructions for your receiving device. If it doesn’t support it, you can add it, but you’ll have to work on the circuitry yourself.

And remember - nothing is impossible (there are crooked hands).

Smart advice: it's better not to watch TV at all. There, on the vast majority of channels there is a complete lie, brainwashing of cattle, and a humiliating amount of advertising (super bonus - also regional advertising). Decide for yourself.

In order for the antenna amplifier installed in the “Polish Grid” antenna housing to work, it must be connected to a power source. The amplifier is powered via a coaxial cable running from the antenna to the TV. This means we need to connect the power supply to this cable. Many users find it difficult to do this. Let's consider a simple connection option.

First you need to cut the end of the television cable (). We step back 1.5 cm from the end of the cable and carefully remove the outer insulation, trying not to damage the screen and the insulation of the central core. Remove the cut piece in a circle outer shell. Then we move the hairs of the screen and the foil back. Next, we retreat 0.5 cm from the moved braid and cut off the inner insulation from the central core in a circle. The cable is ready for connection.

Carefully place the cut cable into a special fastener on the power supply separator board. It is necessary that the cable braid tightly touches the lower contact pad, and the central core is inserted into the screw retainer.

We tighten the screws until the cable contacts are completely secured.

The more I understand the modern element base, the more I am amazed at how easy it is now to make electronic devices that previously could only be dreamed of. For example, the antenna amplifier in question has an operating frequency range from 50 MHz to 4000 MHz. Yes, almost 4 GHz! In the days of my youth, one could simply dream of such an amplifier, but now even a novice radio amateur can assemble such an amplifier on one tiny microcircuit. Moreover, he has no experience working with ultra-high-frequency circuitry.
The antenna amplifier presented below is extremely simple to manufacture. Has good gain low level noise and low current consumption. Plus a very wide range of work. Yes, it is also miniature in size, thanks to which it can be embedded anywhere.

Where can I use a universal antenna amplifier?

• - As a TV antenna signal amplifier for receiving both digital and analogue channels.
• - As an antenna amplifier for an FM receiver.
• - etc.

Antenna amplifier characteristics

• Operating range: 50 MHz – 4000 MHz.
• Gain: 22.8 dB - 144 MHz, 20.5 dB - 432 MHz, 12.1 dB - 1296 MHz.
• Noise figure: 0.6 dB - 144 MHz, 0.65 dB - 432 MHz, 0.8 dB - 1296 MHz.
• Current consumption is about 25 mA.

Making an antenna amplifier

Scheme

Amplifier board

Setup and testing

Schema addition

Connecting the amplifier to the antenna