Active TV signal splitter. Encyclopedia of radio electronics and electrical engineering

Encyclopedia of radio electronics and electrical engineering / Television antennas

Comments on the article

At present, house cable networks for the transmission of television signals are widespread: systems for the collective reception of terrestrial television, as well as cable television. However, the number of signal consumers in a separate apartment is constantly growing - several TVs, VCRs, TV tuners for personal computers. This leads to the fact that the television signals that enter the apartment have to be divided many times, that is, several splitters are used. As a result, signal levels may decrease so much that they are insufficient for high-quality TV reception.

In this case, it is necessary to install a so-called television "antenna" amplifier at the place where the signals enter the apartment. But if you apply the "first available" amplifier, you can get a negative result. The fact is that such an amplifier must have not only a gain of 10 ... 20 dB, good sensitivity and the required bandwidth, but also a large dynamic range. The need for this is due to the fact that the frequency range of television broadcasting is heavily loaded not only with television signals, but also with the signals of VHF radio stations (both broadcasting and amateur and office), cell phones, etc. If the amplifier has insufficient dynamic range, then it may be overloaded and the occurrence of crosstalk, which degrades the quality of reception, up to a breakdown in image synchronization. Therefore, an amplifier with a large dynamic range is needed.

In addition to buying, the amplifier can be made independently according to the description in the author's article "Television antenna amplifier with a large dynamic range" ("Radio", 2005, No. 9, pp. 11, 12). At the same time, an additional function of dividing (branching) the signal can be assigned to it. The result is an active TV signal splitter.

Fig. 1

A diagram of such an active splitter is shown in fig. 1. Its basis is a specialized microcircuit of the medium power amplifier of the VHF range. It provides a gain of about 20 dB over the entire TV broadcast frequency range and an output power of about 18 dBm with a 1 dB gain reduction. Noise factor - 3...4 dB.

A divider R1R2 is installed at the input of the amplifier, which provides matching, increases the stability of the amplifier stage, creates a circuit for draining static electricity, but attenuates the signal by about 3,5 dB. The signal splitter itself in three directions is assembled on resistors R4-R6 and attenuates the signal by 4 ... 5 dB. Diode VD1 protects the DA1 chip from voltage pickups of negative polarity. The overall transfer coefficient of the device is 10 ... 12 dB.

Fig. 2

All parts of the splitter are placed on a printed circuit board made of double-sided foil fiberglass, a sketch of which is shown in fig. 2. The second side of the board is left with a metallized and soldered foil connected at the edges to the common wire of the first side. In addition, through the holes in the board, both sides are connected by pieces of tinned wire. The input and output cables a few centimeters long are soldered directly to the board, they must be with fluoroplastic insulation, sockets XW1 - XW4 are mounted at their ends. The board is placed in a protective plastic casing, for example, a case from a marker or lipstick is suitable.

The amplifier uses capacitors K10-17v, but similar imported ones can be used, and fixed resistors P1-12 of size 1206. High-frequency connectors XW1-XW4 - any suitable ones that are suitable for operation in the VHF band, for example, type "F". Others are also applicable in the amplifier (microcircuits, the parameters of which are indicated in the article mentioned above. If possible, you should choose a microcircuit with a higher output power.

Fig. 3

The supply voltage is supplied via a cable connected to socket XW2. At the other end of the cable, a separate decoupling device is installed, the diagram of which is shown in Fig. 3. A stabilized power supply with an output voltage of 12 V and a current of at least 100 mA is connected to it. If it is possible to place the power supply at the location of the splitter, then the block is connected in accordance with the diagram in fig. four.

Fig. 4

The design of a separate decoupler is similar to a splitter. All parts are mounted on a printed circuit board made of double-sided foil fiberglass according to Fig. 5. Choke L1 - EC24 with inductance 1...10mkH. It can be made independently by winding 2,5-3 turns of wire PEV-10 15 on a mandrel with a diameter of 2 ... 0,2 mm.

Fig. 5

Establishing the device is reduced to checking the mode for direct current. The output of the microcircuit should have a voltage of about 4 V, and at the input - about 2,5 V. If it turns out that the signal for the TV is too large and distortion appears, then you should increase the resistance of the resistor R1 by 2 ... reduce the resistor R3 by the same amount.

Author: I. Nechaev, Moscow; Publication: radioradar.net

See other articles Section Television antennas.

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 Smartphone Micromax Canvas XP 4G 10.05.2016 Micromax has launched an affordable Canvas XP 4G smartphone that uses MediaTek hardware platform and Android 5.1 Lollipop operating system. The new product is based on the MT6735A processor, which contains four 64-bit ARM Cortex-A53 cores operating at a clock frequency of 1,0 GHz. The chip includes a Mali-T760 graphics accelerator. Despite the use of a relatively low-power chip, the developer equipped his offspring with 3 GB of RAM. The touch display, made on an IPS matrix, has a diagonal of 5 inches and has a resolution of 1280 x 720 pixels (720p format). The main camera is endowed with an 8-megapixel OmniVision sensor and LED flash. The front has a 2-megapixel camera. The device carries on board a flash module with a capacity of 16 GB (expandable with a microSD card), Wi-Fi 802.11b/g/n and Bluetooth 4.0 wireless adapters, a GPS navigation system receiver and a basic set of sensors. Power is provided by a 2000 mAh rechargeable battery. The smartphone supports fourth-generation mobile networks 4G/LTE; It is possible to install two SIM-cards. It will be possible to buy a novelty at a price of about 110 US dollars.

Other interesting news:

▪ Electronic screen for information protection

▪ Cell remote control

▪ The laser gun will fly through the weeds

▪ Collagen fibers grow like a sunflower

▪ New FLUKE 87V Digital Multimeter

News feed of science and technology, new electronics

Interesting materials of the Free Technical Library:

▪ section of the site Microcontrollers. Article selection

▪ Bungalow article. Tips for the home master

▪ article How do we grow? Detailed answer

▪ article Molokan compass. Legends, cultivation, methods of application

▪ article Conductive conductors. Encyclopedia of radio electronics and electrical engineering

▪ article How to remove the ring? Focus secret. Focus Secret

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