Watching TV is one of people's favorite activities. And of course, I want the image on the screen to be of high quality. But it doesn't always work out. Antenna amplifiers are used to amplify the signal and picture quality.
What is it and what is it for?
Antenna amplifier is a device needed to increase the level of the signal that goes to the antenna. That is, with an amplifier, the quality of the channels is much higher.
Use an antenna amplifier for television in such cases:
- Weak TV signal.
- The TV antenna is not correctly selected.
- Long distance to telecentre.
Usually, a television antenna amplifier is used to operate in the decimeter or meter wavelength range. In addition, they can also be used to receive channels at a fairly large distance from the transmitter. This is possible in rural areas.
Varieties of amplifiers
Devices may differ in appearance and have different parameters. Some of them may work forvery remote areas, while others are applied only at close range. Install antenna amplifiers for TV near indoor or outdoor receivers.
Amplifier come in:
- Range. These devices include antenna amplifiers SWA and LSA. Quite often they can be found in lattice-type antennas. The devices allow you to receive signals from stations located at considerable distances. They improve picture quality and eliminate interference (noise).
- Multi-range. This category includes amplifiers such as ALCAD and TERRA. They improve the quality of the received picture from receivers that are installed on high masts. Designed for long range and close range. They can receive several signals from different receivers and combine them into one.
- Broadband. Common in the home. Since, due to its ability to improve the quality of the resulting image on several devices at once, they are often mounted in apartment buildings. Can operate in both UHF and MW bands.
By type, antenna amplifiers can also be divided into:
- Domestic. That is, those that are installed next to the receiver. They are quite convenient to use, but the signal may be worse due to cable losses.
- Mast. They are installed directly on the mast, and the power is supplied using a coaxial cable. They do an excellent job with the main task, but are not durable. They usually last for several years. They can be damaged during a thunderstorm or oxidized when exposed to water.
Each of the types of television antenna amplifiers is designed to improve the quality of the received signal.
Amplifier device
The device of antenna amplifiers is not complicated. It consists of two boards connected according to a special scheme. Apply such a scheme to reduce the noise level that occurs during operation of the device. To adjust the frequency range, a special capacitor is mounted in the oscillatory circuit.
The input circuit is a high pass filter. It is placed on special elements. The loop frequency in the first range is close to 48.5 MHz, and in the second - about 160 MHz. Thanks to the use of resistors, the operating modes are set.
Using the selection of the value of resistance, as a result, you can get a voltage and current of 5 volts or 5 amperes, respectively. In this way, you can amplify the signal quality to no more than 4.7 dB at a frequency close to 400 MHz.
The amplifier can be powered by a 12 volt power supply. This allows it to be installed in cars. To ensure the correct operation of the device, it is enough to use a stabilized source, which is a diode bridge and an electrolyte of 1000 uF.
The amplifier can be connected directly to a power source using the coaxial antenna cable. In this case, you must not forget about the line power choke. The TV is connected to the amplifier through a small capacitor.
How the device works
The principle of operation can be cited using the example of an antenna amplifier for digital television SWA 36.
The device has two broadband amplification stages. The signal from the antenna passes through a matching transformer, which is located in the antenna box, and a capacitor. Then the signal goes to the first transistor? connected according to the scheme with a common emitter (OE), where it is amplified and the operating point is stabilized due to the action of negative feedback (NFB) using a resistor. Frequency equalization is not available on the first stage.
Now the line signal passes through the capacitor to the transistor. In the second stage, frequency correction occurs. OOS is performed by voltage through resistors. To avoid large gain losses, one of the resistors is shunted in current by a capacitor with a relatively small capacitance (10 pF) to correct the frequency response of the device. Further, the already amplified signal is sent to the television receiver.
How to choose an amplifier?
The quality of the device operation depends on the correct choice of the antenna amplifier for digital television. After all, an incorrectly selected device will not bring the expected result.
So, in order to choose the right amplifier, you need to consider the following nuances.
- Antenna type and device model for amplification. For example, SWA type amplifiers are suitable for a lattice antenna. It is important to remember that it is permissible to put a broadband amplifier on a narrow-band receiver. But by no meansvice versa.
- The value of the output signal. A minimum of 100 dBμV is considered the best option.
- Working frequency range. These frequencies should be received not only by the antenna, but also by the television receiver. The amplifier must be set to amplify these signals. If either the TV receiver or the antenna cannot receive these frequencies, then there will be no sense from a digital antenna amplifier either.
- The choice also depends on the type of terrain and signal quality. If a strong signal is observed, then a wide-range one is quite suitable. But a device that operates within a certain range is considered optimal.
- Gain. The amplifier is selected depending on the distance between the TV and the nearest station emitting a signal. The value of the coefficient should be optimal. But, for example, with a distance of less than 10 km, there is no point in the amplifier, a suitable antenna is enough. Otherwise, the device must be selected according to the distance and not purchased with a gain greater than necessary.
- Current consumption. Experts recommend devices rated for 30-60 A.
- Noise factor. The lower the value, the higher the image level. The recommended value is no more than 3 dB.
DIY Amplifier
You can make an antenna amplifier with your own hands. For this you will need:
- two cans, for example, from beer;
- pair of self-tapping screws;
- adhesive tape or electrical tape;
- wooden stick (can be replaced with an old trempel);
- power cable, length is calculated based on needs;
- plug.
Production will take 10-15 minutes. Assemble the device as follows:
- Tin cans and a stick are connected to each other at a distance of 7-7.5 cm. Electrical tape is used for connection. If the jars have rings, you can attach the power cable to them.
- Self-tapping screws are screwed into the banks. The ends of the cable must first be stripped. You can do this with a utility knife. Now the ends can be fixed with screws.
- To make the device more stable, the stick is connected to the wire using electrical tape.
- Banks should be covered with a plastic flask. To do this, it is enough to remove the neck and bottom from the bottle.
- Now a hole is made in the middle of the container through which the cable must be pulled.
- When the device is assembled, pour boiling water over the bottle. It will change its shape and seal the hole.
- Now you can connect the device and configure the resulting device.
As you can see, making an antenna amplifier with your own hands is a simple matter.
Connect to TV
Connect the antenna amplifier as follows:
- Install the amplifier as close to the TV as possible. This is true for branded devices and do-it-yourself ones. The exception would be room amplifiers that have short cables.
- Be sure to read the instructions before connecting. Often, the nuances necessary for high-quality work are indicated there.
- Ifafter connecting the device, the picture quality leaves much to be desired, then perhaps the problem is in the integrity of the antenna or in the frequency difference.
- Connection should only be made with de-energized appliances.
You can connect the device using the coaxial wire of a conventional antenna. But for this, a special choke must be located along the power line. If the amplifier is powerful, then for high-quality work it is connected through a capacitor element with a low capacitance. Adjusting the device is easy. It is enough to transfer the resistor element to the middle and adjust until the picture is of the highest quality.
Results
There are situations when it is necessary to boost the TV signal. There is a special device for this - an antenna amplifier for a TV. Although this is a simple device, you also need to choose it correctly. But the connection and setup is quite simple. Such a device can be made from improvised materials, spending a minimum of time on it.
