Encyclopedia of radio electronics and electrical engineering / Civil radio communications

 Comments on the article

Without claiming to be the author of the idea to use a switching power supply from a computer to power an imported transceiver, I want to share my experience in its alteration and operation. The need for such a light power source arose on one of the trips to the country, where I constantly took the transceiver with me. If the mass of the YAESU FT-840 is quite tolerable, the weight of its native power supply, you see, leaves much to be desired.

The circuitry of computer power supplies from many manufacturers does not differ significantly from each other, and it can be assumed that the proposed procedure for carrying out alteration work, which does not affect the main functional units, is applicable to most switching power supplies for personal computers of the AT class. According to the described method, the author redid four power supplies.

Below is a step-by-step instruction for the conversion.

Connect the power supply to a network with a voltage of 220 V. Connect a wire resistor with a resistance of 12 ... 1,3 Ohm (1,5 - 1 ... 8 A) to its +9 V output. If the output voltage does not change, we can assume that the unit is suitable for rework.

Open the power supply and remove from the board all the wires coming from the -5 V, -12 V, +5 V power supply outputs, except for the common wire (GND) and the +12 V source wire.

Remove the socket for connecting the monitor, and in its place, on the insulating plate, install two terminals. Designate the terminals as "+12 V" and "-12 V".

Using the +12 V source wire (yellow wire), make several turns on a ferrite ring magnetic circuit of size K28x16x9 mm, grade M2000NM and connect them (solder) to the "+12 V" terminal.

Connect (solder) the black wires "GND" to the "-12 V" terminal.

Parallel to these terminals, connect an oxide capacitor 33 microns x 25 V.

In the hole in the case, through which the power wires previously went out, install a power switch (-220 V) with backlight, having previously filed the hole with the desired shape.

In the mains rectifier (Fig. 1), filter capacitors C5 and C6 with a capacity of 220 microns are replaced with capacitors of 330 microns x 350 V. Since the latter are large in size, they are soldered on legs made of copper wire with a diameter of 1 mm.

Replace the rectifier diodes of the +12 V source (an assembly of two diodes on the VD19VD20 radiator - in Fig. 2) with KD2999 diodes (2 pcs.) With any letter. New diodes should be installed on a separate aluminum profile-corner (TNX RV4HV) and already fixed on the radiator. The best option is to install an imported assembly of diodes with a Schottky barrier with parameters Ipr \u25d 6 A, Uo100p \uXNUMXd XNUMX V - less voltage drop and, consequently, less heating of the diodes.

Capacitor C25 at the output of the +12 V source should be replaced with a capacitor with a capacity of at least 4000 microns and an operating voltage of 16 V.

To increase the output voltage of the +12 V source to +13 ... 14 V, it is necessary to break the printed conductor coming from the midpoint of the +5 V source rectifier assembly, and include 1-2 silicon diodes with lnp = 1 ... 2 A in direct connection, as shown in fig. 2 (VD1*, VD2*). The author used KD226A diodes.

After that, the transceiver began to give its "native" 100 W to the antenna (at +12 V only 80 ... 90 W). The specified circuit supplies a feedback voltage for the output voltage stabilization stage; reducing this voltage with a forward-biased diode by about 0,6 V led to an increase in output voltages, including the source + 12V to + 13V; instead of a diode, you can also use a resistor, choosing its resistance to obtain a voltage of +13 ... 13,5 V.

Excess voltage in the power supply circuit of the PSU cooling fan should be extinguished by also turning on several diodes.

Protection against overloads and short circuits at the PSU output is adjusted by selecting the number of turns on the current sensor, a ring with several turns of wire located near the transistors.

After the rework, my PSU provided Uout = 14,2 V at a load current of 20 A. It turned out to be light (weight - about 700g), small (80x100x150 mm), reliable power supply with output short circuit protection. Various emergency situations were simulated - at the output of the power supply unit, the voltage disappeared instantly.

The output voltage of the power supply unit changes by no more than 30 ... 40 mV when the mains voltage changes from 180 to 280 V. At idle, it consumes about 7 watts from the mains. Efficiency when the load current changes from 5 to 20 A - within 80 ... 85%.

The unit has been in operation since May 2002 at the dacha. Mains voltage during the day can vary from 195 to 235 V, but the quality of the FT-840 transceiver does not affect. There is no spurious modulation of the transceiver signal during transmission. In comparison with the power supply unit assembled according to the traditional scheme, there were no differences in the operation of the transceiver.

Author: N. Shadrin (RZ4HX), Togliatti, Samara region

See other articles Section Civil radio communications.

Read and write useful comments on this article.

<< Back

<< Back

Latest news of science and technology, new electronics:

Machine for thinning flowers in gardens 02.05.2024

In modern agriculture, technological progress is developing aimed at increasing the efficiency of plant care processes. The innovative Florix flower thinning machine was presented in Italy, designed to optimize the harvesting stage. This tool is equipped with mobile arms, allowing it to be easily adapted to the needs of the garden. The operator can adjust the speed of the thin wires by controlling them from the tractor cab using a joystick. This approach significantly increases the efficiency of the flower thinning process, providing the possibility of individual adjustment to the specific conditions of the garden, as well as the variety and type of fruit grown in it. After testing the Florix machine for two years on various types of fruit, the results were very encouraging. Farmers such as Filiberto Montanari, who has used a Florix machine for several years, have reported a significant reduction in the time and labor required to thin flowers. ... >>

Advanced Infrared Microscope 02.05.2024

Microscopes play an important role in scientific research, allowing scientists to delve into structures and processes invisible to the eye. However, various microscopy methods have their limitations, and among them was the limitation of resolution when using the infrared range. But the latest achievements of Japanese researchers from the University of Tokyo open up new prospects for studying the microworld. Scientists from the University of Tokyo have unveiled a new microscope that will revolutionize the capabilities of infrared microscopy. This advanced instrument allows you to see the internal structures of living bacteria with amazing clarity on the nanometer scale. Typically, mid-infrared microscopes are limited by low resolution, but the latest development from Japanese researchers overcomes these limitations. According to scientists, the developed microscope allows creating images with a resolution of up to 120 nanometers, which is 30 times higher than the resolution of traditional microscopes. ... >>

Air trap for insects 01.05.2024

Agriculture is one of the key sectors of the economy, and pest control is an integral part of this process. A team of scientists from the Indian Council of Agricultural Research-Central Potato Research Institute (ICAR-CPRI), Shimla, has come up with an innovative solution to this problem - a wind-powered insect air trap. This device addresses the shortcomings of traditional pest control methods by providing real-time insect population data. The trap is powered entirely by wind energy, making it an environmentally friendly solution that requires no power. Its unique design allows monitoring of both harmful and beneficial insects, providing a complete overview of the population in any agricultural area. “By assessing target pests at the right time, we can take necessary measures to control both pests and diseases,” says Kapil ... >>

Random news from the Archive The taste of wine depends on the shape of the glass. 02.11.2002 This conclusion was made by chemist Kari Russell from the University of Tennessee (USA). After pouring red dry merlot into a tall narrow glass, into a pot-bellied cognac-type glass, and into a wide shallow glass, he then measured the content of phenolic compounds in the bottled wine. These aromatic compounds are important for the bouquet of wine and have health benefits. It turned out that after bottling in all three glasses, the content of gallic acid increased compared to the wine in the bottle. The chemist believes that during bottling, part of the tannins of the wine, as a result of contact with air, turns into gallic acid. After 10-20 minutes, the content of gallic acid in a tall glass and in cognac remained the same, but in a wide one it fell. Since in a wide glass there is more contact surface of wine with atmospheric oxygen, the gallic acid in it is oxidized, turning into esters, giving the wine a more pronounced dry taste. True, only a specialist taster or a well-trained amateur can notice these changes. Similar, although less pronounced, changes occurred with other phenolic compounds.

Other interesting news:

▪ Gaming TV Redmi Gaming TV X Pro

▪ Solar rooftops of the British Isles

▪ insulin on gold

▪ Mellanox Innova IPsec 40GbE Encrypted Network Adapter

▪ Increasing the rate of photosynthesis

News feed of science and technology, new electronics

Interesting materials of the Free Technical Library:

▪ section of the site Spy stuff. Article selection

▪ article Accounting and control. Popular expression

▪ Did King Arthur Really Exist? Detailed answer

▪ Melon article. Legends, cultivation, methods of application

▪ article Night light brightness control. Encyclopedia of radio electronics and electrical engineering

▪ article Egyptian proverbs and sayings. Large selection

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