Menu English Ukrainian russian Home

Free technical library for hobbyists and professionals Free technical library


ENCYCLOPEDIA OF RADIO ELECTRONICS AND ELECTRICAL ENGINEERING
Free library / Schemes of radio-electronic and electrical devices

Broadband antenna amplifier for TV signals. Encyclopedia of radio electronics and electrical engineering

Free technical library

Encyclopedia of radio electronics and electrical engineering / Antenna amplifiers

Comments on the article Comments on the article

For repetition by radio amateurs, a relatively simple antenna amplifier for television signals in the MB and UHF bands is proposed

The amplifier, the schematic diagram of which is shown in fig. 1, consists of two stages, assembled according to the OE scheme and covered by a common negative feedback circuit (NFB) for direct current through the resistor R2. OOS for alternating current is negligible.

Broadband TV Antenna Amplifier

The main amplification of the signal is provided by the first stage. The second stage, covered by parallel (through resistor R1) and serial (through resistors R4 and R5) OOS. serves to equalize the total amplitude-frequency characteristic (AFC) of the amplifier. Capacitors C4 and C5 in the emitter circuit of the transistor VT2 (at the specified capacitance values) correct the frequency response in the lower and middle frequencies of the passband.

The feature of the amplifier is that the resistor R1 performs three functions: it serves as a load for the transistor VT1. creates a parallel OOS of the transistor VT2 and together with the transistor VT1 forms a voltage divider to power the base of the transistor VT2. This allows a few decibels to increase the gain compared to traditional amplifiers [1. 2] and reduce the number of applied elements.

On fig. 2 shows the frequency response of three amplifiers assembled according to the considered scheme, but with different transistors: 1 - on KT3101A-2; 2 - on 2T657A-2; 3 - on KT368A. In the case of using KT368A transistors, a resistor R2 with a resistance of 4 Ohms and a capacitor C390 with a capacity of 4 pF are installed in the emitter circuit of the transistor VT30 (elements R5 and C5 are absent). The studies were carried out in a 50-ohm path using an XI-43 frequency response meter. The standing wave ratio (SWR) of the amplifiers on the input side was within 2...2.5.

Broadband TV Antenna Amplifier

An analysis of the characteristics shows that the maximum operating frequency of the amplifier reaches 0.2 ... 0.25 of the cutoff frequency of the transistors used. Therefore, in UHF amplifiers, it is desirable to use low-power microwave transistors designed to operate in cascades assembled according to the OE circuit (two emitter leads) and having a cutoff frequency of more than 3 GHz. Only for the MB range, RF transistors with a cutoff frequency of at least 1 GHz are suitable.

The amplifier uses MLT resistors and K10-17 capacitors. but KM and KD will do. All elements must have a minimum lead length.

The amplifier is assembled on a foil fiberglass board, the drawing of which is shown in Fig. 3. Resistor R1 is soldered to the terminals of the transistor VT2, placing it above it (if the transistor has lamellar terminals).

Broadband TV Antenna Amplifier

The voltage between the collector and emitter of transistors VT1 and VT2 is approximately 4 V. This is achieved by selecting the resistor R2. With powerful interfering signals at the input of the amplifier, filters are installed, the parameters of which are indicated in [2. 3].

Literature

  1. Red E. Handbook on high-frequency technology: Schemes, blocks. 50 ohm technique: Per. with him. - M.: Communication. 1990.
  2. Nechaev I. Combined amplifiers of TV signals - Radio. 1997. No. 10. p. 12. 13.
  3. Nechaev I. Adders of television signals. - Radio. 1996. No. 11. p. 12. 13.

Author: N. Turkin, St. Petersburg

See other articles Section Antenna amplifiers.

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

Water replacement for lithium-ion batteries 21.10.2023

Scientists at the Korea Institute of Science and Technology (KIST) are proposing a shift from lithium-ion batteries to aqueous batteries, which promise to be safe, efficient and more environmentally friendly.

Lithium-ion batteries, despite their widespread use, face problems with explosion hazards and high costs, as well as negative environmental impacts. Researchers at KIST propose using water batteries as a safer and more affordable alternative.

Aqueous batteries use water-based solutions instead of traditional organic solvents, making them safer and more economical. However, there is a problem with dendrites and corrosion of metal deposits, which can impair the performance and safety of batteries.

The researchers solved this problem by creating a composite catalyst made from manganese dioxide and palladium. This catalyst is capable of absorbing hydrogen, thereby preventing internal pressure and ensuring the safety of the battery. This solution also reduces electrolyte wear and ensures long battery life.

Water batteries promise to be safer, more affordable, greener and longer lasting, making them a promising option for the future of energy storage.

Other interesting news:

▪ The US Army wants to work with tablets with gloves

▪ Mud volcanoes on Mars

▪ Sewing machine with computer

▪ Universal Donor Blood

▪ Greenhouse in which it is cool

News feed of science and technology, new electronics

 

Interesting materials of the Free Technical Library:

▪ site section Power supplies. Article selection

▪ article If you want to be healthy, temper yourself. Popular expression

▪ article Where and when was the bike race organized to escape to another country? Detailed answer

▪ article Tourist dinghy. Personal transport

▪ article Digital voice recorder on a single chip. Encyclopedia of radio electronics and electrical engineering

▪ article Radiotelephone converter based on the CD4047 chip. Encyclopedia of radio electronics and electrical engineering

Leave your comment on this article:

Name:


Email (optional):


A comment:





All languages ​​of this page

Home page | Library | Articles | Website map | Site Reviews

www.diagram.com.ua

www.diagram.com.ua
2000-2024