Walkie-talkies with a frequency range of 400-470 MHz. Reviews and useful information for radio amateurs. What is SWR or SWR

Good day. This information will be of interest to those who have already decided on a model that undoubtedly meets your aesthetic and consumer needs.
When choosing which one you need to pay attention to the frequency with which you will have to work. Each state, being the owner of radio frequencies, sets a number of significant restrictions on their use. Based on this, walkie-talkies are divided into two main types - professional and amateur. Amateur radios have permitted power and can be used without a special license. But to use professional walkie-talkies, you will need to register the device.
So, in the line of radio transmitting devices we offer, you can see portable or mobile transceivers designed for operational communication, frequency range and MHz.
Radio stations of the CB band (CB), an abbreviation for “civil band” (English CB, Citizens’ Band), adopted to denote license-free, accessible to all citizens, radio communications on short waves in the 27 MHz range are used all over the world, usually by car enthusiasts.
If your attention is drawn to single-band walkie-talkies with a frequency range of 400-470 MHz, then you need to know what this includes:
Walkie-talkies with the LPD 433 standard range, (Low Power Device) - radio frequency range of 69 channels in the range 433-434 MHz for low-power devices up to 0.01 W. This frequency range is the same as the European range for similar applications;
The PMR (Private Mobile Radio) standard range is a European license-free system (commonly referred to as PMR446) for mobile radio communications in the VHF range with a frequency of 446,000-446,100 MHz and a maximum output power of 0.5 W. Intended exclusively for private use and to meet the domestic radio communication needs of the general public.
As noted above, walkie-talkies with such frequency ranges are amateur and do not require licensing or registration.
Particular attention should be paid to single-band radios with a frequency range of 136 -174 MHz. VHF (VHF), more precisely, part of the VHF range - from 136 to 174 MHz; in Russia, it is necessary to obtain permission to use radio frequencies (rent a frequency) from the Radio Frequency Center and register radios with Goskomnadzor. This is explained by the fact that mobile telephony, television signal transmission, satellite communications, radio communications of law enforcement and security agencies, military communications, aero communications, etc. are carried out in this frequency range. The frequency range is professional. Also in this range there is a narrow frequency band - 144-146 MHz, allocated for radio amateurs (you need to pass an exam for the category, register the radio station with Goskomnadzor).
Dual-band radios are of interest. The frequency range will look like this - 400-470 / 136-174 MHz. Such radios work in both the amateur and professional ranges. It will be possible to use the LPD 433 and PMR446 standards at the permitted frequencies, and in case of a critical situation when the assistance of the Ministry of Emergency Situations, law enforcement agencies, etc. is needed, the range of 136-174 MHz can be used.
I hope that this article will help you finally decide on the walkie-talkie model and get a reliable assistant for work and leisure.

Decree of the Government of the Russian Federation of October 13, 2011 No. 837 “On introducing amendments to Decree of the Government of the Russian Federation of October 12, 2004 N 539”, land mobile communication stations for personal use in the 27 MHz range were removed from the list of radio-electronic equipment and high-frequency devices subject to registration (CB range) with a permissible transmitter radiation power of no more than 10 W.

New car radio YAESU FT-1907M with a wide operating frequency range of 400-470 MHz and high output power of up to 55 W!

Description:

The FT-1907 radio station is a new transceiver in the 400-470 MHz range (wavelength 0.7 m), intended for use for amateur radio purposes. However, since Vertex Standard puts the quality of the equipment it develops at the forefront, the design of this model, like all new Vertex Standard amateur radio stations, meets the requirements of the international standard MIL STD 810, which is designed to ensure long-term use of the transceiver even in the most severe conditions. The walkie-talkie can be used for taxis, truckers, hunting and fishing, for trophy races and other adventures.
The station supports direct frequency entry mode in the amateur radio range 400-470 MHz; the most frequently used communication frequencies can be recorded in the station’s memory (with an alphanumeric identifier) for quick transition to these channels. The mode of cloning the memory contents of one station to others is supported. For ease of use, the volume and squelch level controls are located on different knobs. CTCSS and DCS transmit/receive system are supported as standard.
The station also comes standard with a DTMF microphone with user-programmable function keys. For compatibility with a wide range of amateur radio equipment, the FT-1907 station has two frequency deviation modes - with wide and narrow deviation.
FT-1907 supports operation mode with the WIRES (TM) system, when several repeaters are combined into one infrastructure using the Internet as a transport network.

Main distinctive features
Wide operating frequency range 400-470 MHz. Includes LPD 433-434 MHz, PMR 446 MHz, FRS/GMRS bands!

High output power up to 50 W! Possibility of power adjustment (4 modes) 5/10/25/50 W. The power level can be saved when programming each of the memory channels

Direct input of operating frequency from the keyboard of a hand-held microphone (push-to-talk)

Bright backlit handheld microphone keyboard
Bright anti-glare radio display
221 memory channels that can be configured into 8 banks
Adjustable microphone sensitivity and frequency deviation in transmit mode (2 modes)
Built-in Morse code training sensor
Bandwidth switch in receive mode (12.5/25 KHz)
Individual programmable access code for the user
Possibility of working via the Internet (WIRES-II)
Dimensions 14x40x14.6 cm. Weight 1200 g.

Contents of delivery:

№	Name	Quantity
	Car radio Yaesu FT-1907M
	Handheld microphone (push-to-talk) MH-48
	Power cables for connecting to a car or stationary power supply (E90217115)
	Spare fuses 15A (Q000081)
	PTT mount (steel)
	Metal station mount + set of screws and screws
	User guide
	Warranty card
	Packing box (cardboard)

Technical specifications:

Options	Car radio YAESU FT-1907M
Frequency range , MHz:
Channel step, kHz	5/10/12.5/15/20/25/50/100
Supply voltage, V	13.8 ± 15%
Operating temperature, C deg.
Frequency stability
Dimensions, mm	140 x 40 x 146
Weight, g
RECEIVER
Sensitivity at 12 dB SINAD, µV
Selectivity, dB	6 dB at 12 kHz 60 dB at 28 kHz
Intermodulation, dB
Bass speaker power, W
TRANSMITTER
Output power (adjustable), W
Maximum deviation, kHz
Type of radiation	16KOF3E (11KOF3E for 12.5 kHz)
Compliance with standard	MIL STND 810 C/D/E
Out-of-band emissions, dB
Max. deviation	5 kHz (2.5 kHz for 12.5 kHz)

The radio range depends on:
1. From the power of the transmitters. Increasing power increases range. Power also depends on the state of charge of the battery, maximum power is achieved when the battery is fully charged.
2. Receiver sensitivity. (the newer the models, the better the set of characteristics)
3. Operating frequency. At higher frequencies, the operating efficiency of small-sized antennas is higher. But a higher frequency passes through obstacles worse (walls, buildings, trees). The best range for portable radios in difficult conditions is 430-440 MHz.
4. From the length of the antennas. Longer antennas have better gain, which provides better receiver sensitivity and greater transmitter radiation efficiency. Any antenna is configured (matched) at the factory; homemade lengthening or shortening of antennas is unacceptable! It is unacceptable to use TV antennas, cables, connectors, they are not compatible in terms of characteristic impedance. Walkie-talkies have 50 ohms. TV has 75 ohms.
5. Presence of interference sources in the operating range.
6. Antenna height(walkie-talkies). That is, the connection from the last floor of the building will be much further than from the first.
For example: 8-watt radio in the range 400-470 MHz. in the city it will hit up to 100 km from roof to roof. and from basement to basement up to 100 meters.
7. For all portable radios, the efficiency (matching) of the antennas strongly depends on the position of the radio. According to test results, the best performance is when The radio is held in the hand, with the antenna facing away from you(from the head), the antenna and part of the arm from the radio to the elbow lie on the same straight line. The worst performance is when the antenna is pressed (close) to the arm, head, or body. Reception and transmission will be significantly It’s better if the radio antennas are parallel to each other, and if the antennas are perpendicular, the connection will be worse.

There are many factors influencing the range, so it is practically impossible to accurately predict what the actual range of a radio station will be in a particular location.
The declared range of the radio station implies the operation of radio stations in line of sight without sources of interference along the way.

What range will powerful portable radio stations operate in the forest?

What is the guaranteed range of a walkie-talkie in the forest?
Almost every hunter asks us this question. Anyone who has already encountered the use of walkie-talkies or long-range radiotelephones knows that the radio communication range very much depends on the terrain and conditions.
For example, a FOREST can be: Coniferous on a plain, without undergrowth, in such a forest the communication range of 6-8 watt radios will be up to 7-10 km. Depending on the density and humidity of the forest.
Deciduous or mixed forest with dense undergrowth, the most difficult forest for radio communications. Usually in such a forest the communication range does not exceed 5-7 km.
Communication conditions worsen even more if the forest has hills and ravines. Connections between different ravines (from ravine to another ravine), located 1 km away. may no longer exist. At the same time, communication from a hill to another hill can reach 20-30 km. The connection from hill to ravine can reach 7-10 km. Along a straight river up to 10 km. On the open water of lakes this is the entire line of sight, up to 30 km.
Walkie-talkies with lower power will have significantly shorter ranges in the forest. The given range examples are maximum for the most powerful and long-range portable radios 6-8 Watt 400-470 MHz.
If you are not satisfied with such a communication range in forest conditions, you need to choose military-style radios, the size and weight of a car battery and an antenna the length of a fishing rod. Only such radios can provide a greater communication range in forest conditions.

What is the communication range of radios on the highway (on the highway)?

For communication between cars, it is best to use stationary car radios with external antennas with a power of at least 8 watts. These walkie-talkies will be able to provide stable radio communication over tens of kilometers.
If you still decide to use portable radios with a power 6-8 watts, the communication range will greatly depend on many factors and fluctuate from 2 km to 20 km.

The main factors that significantly affect the communication range of walkie-talkies on the route:

Vehicle equipment. Glass tinted with metallized film, heated glass, glazing area. All these factors take a significant part of the radiation from the radio antenna, reducing the communication range.
Vehicle seat height. The higher your cars are, the further the connection will be. The difference between two low sedans and high jeeps can reach 20-30%.
Route locations. If communication occurs from mountain to mountain, then the range can reach 20 kilometers. If there is a mountain between the cars, then the range can be reduced to 1 km. On straight sections, the range will be up to 5 times greater than on sections winding in the forest or between mountains.
Traffic congestion. The more cars on the highway, the worse the connection, the shorter the range. Tall trucks, buses, KAMAZ trucks create a natural barrier to radio waves, absorbing them or reflecting them in the opposite direction. Almost all cars have radio-electronic equipment inside (cell phones, navigators, computers...) that emit slight interference; with a large concentration of cars on the communication line, this interference becomes significant.

In addition to these factors, there are many more factors that affect the communication range of walkie-talkies. There may be a high mountain on the side of the route and the signal can be reflected from it, increasing the communication range significantly, despite other factors. Rainy and humid weather greatly impairs communication; wet car windows absorb the radio's radiation more strongly, reducing the communication range.
Even under the worst conditions, powerful portable radios (7-8 Watts) provide a communication range between vehicles of 1-2 km. Usually this is quite enough if you are traveling in a group of cars.

*We do not recommend using external car antennas with walkie-talkies. The wire from the external antenna quickly breaks down due to frequent kinks, which leads to the burnout of the walkie-talkie transmitter.

Walkie-talkie power and range

Which band is best for portable radios?

In the range CB (27 MHz)“long wave” radio waves can be reflected from the ionosphere (sky), circle the earth and travel thousands of kilometers. But this requires very high transmitter power (more than 100 watts) and very huge antennas.
In a portable version with low power and short antennas, walkie-talkies in this range work very poorly, since small antennas cannot effectively emit and receive long radio waves. And there is not enough power for the reflected signal to reach the ground. This range is only good for powerful stationary radio stations with large antennas.
This range is popular among truck drivers; powerful stationary car radios and external antennas about 2 meters long are used.

VHF (136-174 MHz) The wavelength is not short enough to transmit and receive the signal well on short portable antennas. But it has good penetrating ability. Works well in car radios with external antennas on the roof of the car. Or in "backpack" type radios. According to customer reviews, in some cases, walkie-talkies in this range work better in the forest. This range is sometimes (not officially) called the "Forest Range".

UHF (400-480 MHz) This is the optimal range for portable radios. The wavelength is short and is radiated and received very efficiently by short antennas. While maintaining fairly good penetrating ability through forests, houses...
All major license-free communication standards are located in this range. LPD, FRS, PMR. Portable radios in this range have the longest range.
Attention! It is prohibited to use frequencies above (more than) 480 MHz in cities, as they interfere with digital television.

DPMR- This is a modern digital modulation standard (data transmission via electromagnetic radiation). New digital modulation capabilities provide higher effective transmit power and higher receive efficiency. Reliable confidentiality of negotiations is ensured due to the possibility of digital encryption with a key of 65536 combinations. Clean and clear sound (digital sound quality). The ability to make individual and group calls to subscribers and many other features.
More details can be found in the official technical documentation for the protocol.
Access Method: FDMA
Modulations: Four-level FSK
Data transfer rate: 4800 bps

900 MHz. The wavelength in this range is very short, which makes it possible to use very small antennas. But waves in this range pass very poorly through obstacles such as house walls, forests, and hills. Communication range can only be obtained under line-of-sight conditions.

Now you should not buy outdated walkie-talkies with one band; new models of dual-band walkie-talkies now cost the same. If you do not have the opportunity to buy a dual-band portable radio, we recommend buying powerful walkie-talkies in the UHF 400-520 MHz range. If, even under some conditions, the VHF range (136-174 MHz) gives a greater communication range in the forest, then it is quite insignificant. But in all other communication conditions (fields, highways, cities, mountains) it is significantly inferior to the UHF 400-520 MHz range. All license-free frequencies are in the UHF 430-450 MHz range.

What are the benefits of a DPMR or DMR digital radio?

Firstly, it gives only advantages, since digital walkie-talkies can operate in normal analog mode and they have all the capabilities of conventional walkie-talkies.
The main advantage of digital communication is that you do not need to use call signs to communicate within a large group. You can call specific subscribers in a group without disturbing others. In analog radios, the whole group hears the call and you must say phrases like “first to fifth..”, “fifth accepted.” Each subscriber is forced to listen to all the conversations of the group, suddenly they say his number or call sign. All this is not needed digitally! Moreover, digital has functions that allow you to immediately see whether the remote radio is receiving your signal or not.
You can see the numbers or names of the subscribers who are calling you (not in the DM-5R).
You get high-quality digital sound without noise.
Safety! Your conversations cannot be listened to from other radios (if the encryption function is enabled).
These are only the main advantages of digital communication; you can find out more about the functions and capabilities of digital walkie-talkies on the detailed description pages (model cards).

LPD channel frequencies:

LPD mesh:
Channel 1 = 433.075 then step +.025 channel and so on up to 434.775 (69 channels)

FRS grid channel frequencies:

1 462.5625
2 462.5875
3 462.6125
4 462.6375
5 462.6625
6 462.6875
7 462.7125
8 467.5625
9 467.5875
10 467.6125
11 467.6375
12 467.6625
13 467.6875
14 467.7125

Walkie Talkie Compatibility

Walkie-talkie buyers often ask: which walkie-talkie model is better compatible with other models.
High-quality walkie-talkie models always meet established communication standards. Frequency settings, modulation level, receiver channel width and other characteristics are made and configured in accordance with the requirements of the standard. All models of high-quality walkie-talkies are highly compatible with each other. Walkie-talkies are of low quality, cheap analogues of popular models, stripped-down versions, often do not meet standards, and only work well with each other. When communicating with other models of walkie-talkies, the communication will be of very low quality (low sound, poor intelligibility, wheezing, noise). That is, there are no such radios that will be perfectly compatible with any low-quality models. We check the characteristics of all radios for compliance with standards; we do not sell models that have significant deviations from the standards.

What are CTCSS and QT/DQT subtones for?

Some channels (frequencies) may have a CTCSS or DCS subtone programmed. Subtone is a subsonic signal that allows you to ignore conversations of other walkie-talkie users who are using the same channel (frequency). Allows you to ignore any man-made interference and noise. When you receive a signal that has a subtone different from the one set in your radio, you will not hear this signal. Likewise, the signals that you transmit will only be heard by subscribers whose subtone matches the one set in your radio.
CTCSS is a constant tone that is added to the transmitted audio. If CTCSS = 67.0 this means that a constant tone of 67 hertz is added to the sound. It is not audible thanks to special subtone filters.
QT/DQT - more modern, an identification code is transmitted at subsonic frequencies.
Comment: Using channels with established subtones frees you from unwanted requests and noise, but this does not mean that your conversations will be confidential. To protect against eavesdropping, you need to buy walkie-talkies with the Scrambler function or digital walkie-talkies.

What is SWR or SWR?

SWR (SWR) - Standing Wave Ratio. All high-frequency devices, cables, connectors, antennas, amplifiers are manufactured with standard impedance. This characteristic impedance is the main indicator of compatibility. All radios and extras. equipment for them is produced with a characteristic impedance of 50 ohms. TVs and extras equipment for them (cables, connectors, antennas) are produced with a characteristic impedance of 75 Ohms. Therefore, cables and antennas for a TV operate in the same frequency ranges as walkie-talkies, BUT THEY ARE INCOMPATIBLE in terms of characteristic impedance.
SWR is measured at the break of any high-frequency circuit and shows the accuracy of compatibility. If the SWR is poor, then most of the signal is reflected back and released as heat. All modern walkie-talkies have a built-in SWR meter. It monitors the SWR of the antenna during transmission and if the SWR is bad, it lowers (limit) the transmitter power. This was done so that the powerful transmitter of the walkie-talkie would not burn out if the antenna was leaned against metal, against the hand, or the walkie-talkie was held incorrectly. This is why it is so important to hold the radio correctly in your hand in order to achieve maximum range. (see first paragraph)

What determines the operating time of a walkie-talkie?

The operating time of the radio depends on:
1. From the battery capacity. The larger the capacity (mAh), the longer the radio will operate.
2. From the frequency of transmission use (PTT button). When a powerful transmitter is running, the station consumes maximum battery power. If the radio has several transmitter power modes, then when using low power, the radio will work longer but with a shorter range.
3. Availability of battery saving functions. The mode when the station receiver works periodically turning on for short periods of time. This mode slows down the time the station turns on slightly when called.
! If the battery is worn out, its capacity is significantly less than that of a new one.
! Deeply discharging a battery dramatically reduces its service life. When the radio is left on after the battery is completely discharged.

What types of batteries are there and how do they differ?

1. NI-Cd Nickel-cadmium - The most inexpensive type. They have a memory effect, it is necessary to observe the charge-discharge cycle.
2. NI-Mh Nickel-metal hybrid - No memory effect, high capacity with the same dimensions.
3. Li-ion Lithium - Lightweight, charges quickly, fears severe frosts. A lithium battery always has electronic circuitry inside to provide control of charge, temperature and other parameters.

What is a repeater?

Repeaters significantly increase the range of radios. If the repeater is installed at a high point (for example, on the Moscow State University building), then the communication range between the radios will be up to 60 km. in the city.
A repeater is a receiver and transmitter that operate at different frequencies. The receiver receives the signal, and the transmitter immediately transmits it at another frequency with high power and to a good antenna.
In order for a walkie-talkie to work through a repeater, it must have function of frequency separation of reception and transmission.
You can find information about amateur radio repeaters in your city on the Internet through search engines.

The hunter got lost in the forest. He walks through the forest, calls his comrades and shouts at the top of his lungs:

Awww!
A bear comes out to the meeting and asks:
- Why are you yelling?
- Yes, I got lost, I think maybe someone will hear.
- Well, I heard, has it become easier?
Laughter is laughter, but in every joke, as they say, there is some truth. Good communication when hunting, fishing, on a hiking trip, or on a scientific expedition is no less important than, for example, having a compass and map. This is especially important when you are in an area that is still unknown to you. I remember one incident told by a familiar huntsman. One hunter got separated from the main group during a roundup hunt and got lost. He was well equipped. It seemed there was nothing to be afraid of. But it turned out that the scale of the map he had did not allow him to get attached to the area, and the compass turned out to be useless, since from the very beginning, he did not take any landmarks, apparently hoping for chance. Cloudy, winter day. There was a thaw, the snow had almost melted. No snow, no trace. All that was left was to hope for luck and the radio station issued by the organizer of the hunt. However, he deviated so far that he had to circle around the forest for more than an hour before the radio speaker hissed. Only then the huntsman, who knew the area well, was able to lead the lost hunter to the others. The hunt, of course, was disrupted, but at least no one was hurt. Another example is also illustrative. This time no one got lost, but the hunt was spoiled by “bad” radio stations, which in the forest, unexpectedly, began to pick up the voices of distant countries and the negotiations of the capital’s policemen. But it was not the radios that were to blame, but the hunters who had chosen their range incorrectly. And in the first case, if the radio stations were more powerful, we might not have had to spend the whole day searching for the missing client. So, the purpose of this article is to help hunters, fishermen, tourists and people engaged in extreme sports in an objective choice of radio communications, which are as important as the right cartridges for hunting, lures for fishing or ropes for climbing into the mountains. Among the huge variety of radio stations that are presented on the modern market, everyone should choose the one that is optimally suited to solve their specific problems. But before moving on to the description of the types and types of radio stations, I offer a short educational program on the theory of radio wave propagation, which will at least help the inexperienced reader understand why some radio stations work further than others, although they have approximately the same technical characteristics. Currently in Russia, the State Committee on Radio Frequencies (SCRF) has allocated the following main ranges for land and mobile radio communications:

In order to determine which range is most optimal for communication in the forest, on the water or in the mountains, let’s delve a little into the theory of propagation of radio waves in the ranges I have indicated. Corresponds to a wavelength of 11m. Radio waves in this range are strongly absorbed by the soil, the connection depends on solar activity. They are able to overcome obstacles in the form of small hills, slopes, buildings 10-15 m high. As a rule, short-range communication in this range is carried out by a surface wave (propagating along the ground). When propagated by a spatial wave (reflected from the ionosphere), communication is possible over many thousands of kilometers. In practice it looks simple. The entire airwaves are filled with signals from radio stations that are located thousands of kilometers away from you, but you will not hear your neighbor, who is, say, a kilometer away. There have been cases when a person said “one” and heard the echo of his voice coming from the speaker. This radio wave wrapped around the globe, due to many reflections from the ionosphere, and returned to its starting point! Corresponds to a wavelength of 2m. In this range, radio waves propagate as direct and reflected waves. Since the surface is not flat, but spherical, the radio communication range is several tens of kilometers. If radio station antennas are located at a height of several tens of meters from the ground, then communication is possible at a distance of up to 100 km. The propagation of radio waves in this range is significantly influenced by the terrain, various obstacles, etc. For example, deciduous forest in this range introduces attenuation of about 6 dB/100m. At different reception points, the signal level can be different and range from strong reliable reception to complete loss of radio communication. This is due to the fact that at different reception points the surface and reflected waves arrive in phase or antiphase. Accordingly, the electromagnetic field strength is added or subtracted, which ultimately affects the level of the received signal. The influence of atmospheric interference and time of day do not significantly affect the propagation of VHF radio waves. Therefore, the connection here is stable at any time of the day. In buildings and reinforced concrete structures, VHF radio waves propagate poorly. . Corresponds to a wavelength of 70 cm. As the frequency used increases, the influence of weather conditions increases and the communication range decreases, since the conditions for the propagation of radio waves in this range approach the conditions for the propagation of light. Microwave radio waves propagate well in the city due to reflection from buildings and reinforced concrete structures. In the forest, radio waves in the 400 range travel worse than VHF. For example, a deciduous forest in this range introduces an attenuation of already 10 dB/100 m. Also, radio waves of this range work well in the mountains, especially in crevices and gorges. Radio communication over short distances in this range is stable and does not depend on the time of day. From the properties of radio wave ranges I have given, we can conclude that for communication in forested and rough terrain, radio stations in the 27 MHz and 136-174 MHz ranges are preferable. For the city and mountains, on the contrary, it is better to use radio stations in the 400-470 MHz range. Now let's try to understand the types of radio stations that are represented on our Russian market. All radio stations can be divided into 3 main groups:

Portable radios

Mobile radios

Base radios Portable radios. First of all, a radio station is a radio-electronic device that consists of a transceiver, an antenna and a power source (battery or battery case). Sometimes radios are also called transceivers. This means that some radio station blocks are used together for reception and transmission in order to save space and cost of the product. Based on their consumer qualities, radio stations are divided into several types. Professional radios generally meet the International Military Standard. This means that the radio chassis is a one-piece cast body, and the top and bottom panels of the radio are made of impact-resistant plastic. All rubber gaskets, under which the transmission and control buttons are hidden, fit tightly to the body of the radio station so that water and dust do not get there. In a word, these are radio stations that are not afraid of splashes, dirt, dust, vibrations, heat and frost. The LCD indicator, if equipped, is positioned so that it will not be damaged if dropped. All professional radios have a minimum of keys and controls. As a rule, this is a channel switch, volume control and 2-3 programmable keys. Nowadays, almost all professional radio stations are programmed from a computer. To program the radio station, special interface cables and software are used, which are produced by radio station manufacturers. The auxiliary keys of the radio station can be programmed so that they switch the power, backlight, mode of turning on and off the speech masker, etc. Almost all professional radio stations operate in simplex mode (reception and transmission on the same frequency) and half-duplex (reception and transmission on different frequencies). The last mode is designed to work through a repeater. Professional mid-range radio stations usually have 16-32 programmable channels. The noise suppressor at these stations is electronic and its response threshold is programmed from a computer. Many professional radios have a selective calling feature. This function is needed when several groups operate at the same frequency. The radio stations of the members of each group are programmed with their own individual or. As a result, members of one group enter into radio communication with each other. At the same time, members of other groups do not hear them and communicate with each other in the same way. Thus, code division of the communication channel occurs. As a rule, all professional radio stations are produced with one range. There are 2 main versions: 136-174 MHz and 420-470 MHz. The latter, in turn, are divided into subbands: 400-430 MHz, 450-490 MHz, or, for example? 400-470 MHz. Amateur radio stations, unlike professional ones, do not have fixed programmable channels, but a smooth digital scale. As a rule, they have a keyboard with which you can enter the operating frequency in the range of 136-174 MHz and 420-470 MHz. One of the main differences between amateur radio stations and professional ones is that the former are programmed entirely from the keyboard and do not require any programmers. They also have memory channels. There are many more of them in amateur radio stations than in professional ones. The latter, as a rule, display only the channel number on the LCD or on the channel selector. Amateur radio stations, in addition to the channel number, also display the operating frequency. And in terms of the number of auxiliary functions, they are much superior to professional ones. In an amateur radio station, you can use the keyboard to set the frequency tuning step, the frequency of the subcarrier subtone, the output power, the spacing between reception and transmission, and much more. Amateur radio stations have a developed auxiliary menu system. At the same time, only the main functions that are most often used by the user are displayed on the keyboard. Amateur radios are the most versatile in use. They have a built-in meter for the received signal level (the so-called S-meter). There are also 2-band amateur radio stations that have 2 operating frequency ranges: 136-174 MHz and 420-470 MHz. They are the most versatile. Can be used both in the forest and in the city and mountains. Some models of these radios have a built-in scanner, i.e. receiver with an extended frequency range from 500 KHz to 1000 MHz. Some can even be equipped with additional modules for measuring air temperature, atmospheric pressure and altitude. Currently, there are a large number of amateur radio stations, the design of which complies with the international military standard MIL STD 810 C,D,E. The Japanese company VERTEX STANDARD went even further. It currently produces the VX-6R and VX-7R waterproof radios. These radios can be submerged to a depth of 1 meter for 30 minutes. , as a rule, are installed on moving objects. For example, cars or snowmobiles. Unlike portable radios, they have an output power of 30-70 W and therefore operate from the batteries of the car’s on-board network. As a rule, these radios are equipped with external communicators, which contain a microphone and a transmit button. Mobile radios according to their functional purpose are also divided into professional and amateur. Professional mobile radios comply with the international military standard MIL STD 810 C, D, E and are manufactured on the basis of a cast aluminum chassis and covered with impact-resistant plastic. In terms of functionality, mobile radios differ little from portable radios and are also programmed from a computer. Amateur and mobile radios are available in both regular and shock-resistant housings. They have a smooth digital scale and allow you to dial the operating frequency from the keyboard, which is located on the remote communicator of the radio station. Mobile radios, as well as portable ones, are produced in the range of 136-174 MHz and 420-470 MHz. Professional radio stations in the microwave range can be produced for certain subbands. For example, 400-430 MHz or 450-490 MHz. Professional mobile radios are produced in single-band VHF and microwave ranges. Unlike professional mobile radios, amateur radios are dual-band and even full-duplex. Such radios sometimes have a built-in inter-band bidirectional repeater mode. They have a large number of various functions that can be called both from the keyboard and from the buttons on the front panel. These radios are not designed for 24/7 operation and are therefore designed for a 50% duty cycle. Professional radio stations, by virtue of their design, are designed for round-the-clock operation and have a 100% duty cycle. External car radios with different types of mounting, which are tuned to the operating frequency, are connected to mobile radios. The same mobile radios are used as base radios, but instead of a car antenna, the base one is connected via a coaxial cable with a characteristic impedance of 50 Ohms. In this case, the radio is powered from an external stabilized power source with an operating voltage of 13.8 V and a current of up to 15 A.