A simple HF converter for a car receiver. Scheme, description

Free technical library

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

A simple HF converter for a car receiver. Encyclopedia of radio electronics and electrical engineering

Free technical library

Encyclopedia of radio electronics and electrical engineering / radio reception

Comments on the article

Shortwave receivers for receiving distant radio stations are currently less common than MW and VHF receivers for local reception. However, any medium-wave receiver can easily be adapted to receive stations in the HF bands. To do this, it is enough to build a simple converter (converter). The advantage of the proposed option is the stabilization of the local oscillator frequency, which significantly increases the reception stability.

The converter is designed to be connected to a car receiver with smooth tuning or fixed in 1 kHz steps (frequency synthesis receivers). The advantage of the proposed design is a minimum of winding elements. The local oscillator frequency is stabilized and has a fixed value close to 10,7 MHz, which allows you to receive broadcast stations in the most "busy" subbands of 25 and 31 m (up and down from the local oscillator frequency).

The diagram of the device is shown in the figure.

A simple HF converter for a car receiver

The signal from the antenna XW1 is fed to the switch SB 1.1, in the lower position of which the signal is transmitted to the input oscillatory circuit L1C2C3C4, continuously tunable within the frequencies of the named short-wave subbands. From the coupling coil L2, the signal is transmitted to the base of the transistor VT2 of the radio frequency amplifier.

The local oscillator is made on the transistor VT1. Its frequency is stabilized using a Z1 piezo filter.

Through the capacitors C7 and C6, the signal is fed to the input of the receiver. These capacitors (one of them is tuned) serve to adjust the input circuit of the receiver and are the equivalent of the capacitance of the antenna cable, in the gap of which the described device is included. Switch SB1 is used to switch the receiver to normal mode for reception in the MW and VHF bands (upper position).

The entire device is assembled on a small board and placed in a case similar to that of the Krona battery.

Coils L1 and L2 are ready, for them a standard oscillatory circuit of the intermediate frequency path of the VHF FM receiver with a frequency of 10,7 MHz (orange marking) is used, from which the capacitor inside must be removed. Piezo filter Z1 with a frequency of 10,7 MHz from the same receiver.

Converter adjustment

When connecting the power supply for the first time, make sure that the current consumption does not exceed 1 ... 2 mA. Then, using an oscilloscope or a voltmeter with an RF probe, you should verify that the local oscillator is working. The amplitude of its oscillations should be within 3 ... .4 V. After the entire device is assembled in the case, connect it to the receiver, connect the antenna to the input of the converter and try to catch the KB of the radio station. In this case, it should be borne in mind that the restructuring of the capacitor C2 of the converter will act as a sub-band switch ("coarse tuning"), and smooth tuning to a station within the sub-band is carried out by the control of the base receiver. This procedure should be done already in the car, having a portable broadcast receiver with a HF band as a reference. The subranges "2 m" and "25 m" are marked on the handle of the capacitor C31. By adjusting the capacitor C8, and, if necessary, by selecting or even excluding C7, you need to find the optimal capacitance corresponding to the maximum reception volume of KB radio stations.

Author: M. Sapozhnikov, Ganei Aviv, Israel

See other articles Section radio reception.

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

The computer is not the enemy of the book 14.02.2007

Parents often fear that the younger generation, being fond of computers, will not read books and generally grow up uneducated. However, experience in the United States has shown that a computer with Internet access, on the contrary, improves reading skills and even improves school grades.

One hundred and forty children aged 12-14, mostly from low-income single-parent Negro families, were provided with home computers and unlimited access to the Internet for a year and a half. Participants in the experience surfed the Internet for an average of half an hour a day, which is small compared to children from families with an average and high standard of living. Those surf the Internet every day for two hours or more.

Only 25% of participants in the experience used programs for instant messaging, and only 16% used email. This is apparently due to the fact that their friends and relatives mostly do not have computers.

During the experience, reading skills have improved significantly. Already after six months of communication with the computer, the school grades of the participants went up, especially among those who spent more time on the Internet. But, interestingly, math grades didn't improve.

Other interesting news:

▪ Smart medicine with artificial DNA

▪ Radar shoots HD video

▪ New DaVinci Media Processor for HD Video Transcoding

▪ Robot waiter Servi

▪ TV and health

News feed of science and technology, new electronics

Interesting materials of the Free Technical Library:

▪ section of the site Normative documentation on labor protection. Article selection

▪ article by Vaclav Havel. Famous aphorisms

▪ article How close are we to the sun? Detailed answer

▪ article Self-oscillating multivibrator. Radio - for beginners

▪ article Switching inputs with mixing. Encyclopedia of radio electronics and electrical engineering

▪ article Low battery indicator for a computer mouse. Encyclopedia of radio electronics and electrical engineering

Leave your comment on this article:

All languages of this page

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