Which amplifier is best for megajet 300

Description and Review

MegaJet MJ-300T- continuation of the once popular model with increased transmitter power. FREE performance test with purchase and FREE setup with purchase with antenna.

Description of the radio station:

1. Appearance of the radio station

The MegaJet MJ-300 Turbo car radio differs from the previous MJ-300 model in increased transmitter power AM-8 W, FM-16 W). The MJ-300 Turbo has compact dimensions (138x40x125) and a light weight - 1 kg assembled. The controls are conveniently located on the front panel, thanks to which you can configure the megajet MJ300 turbo radio station to the optimal operating mode. Thanks to the bright and comfortable backlighting of the front panel, as well as the LCD display, which displays the channel number and RX/TX signal level indicator, it is convenient to work with the MegaJet MJ-300 Turbo CB radio station even in the dark.

The stamping quality of the plastic parts is very good. The front panel is simple, has a minimum of buttons and knobs, and a small indicator, but the MegaJet MJ-300 Turbo radio has some differences in appearance from the MegaJet MJ-100. The radio station is made on the “600” technology platform (modern multifunctional radio stations MJ-600 and MJ-600plus are produced on this platform). The longitudinal size of the case is only 125 mm, which allows you to place the radio station in the limited space of any car dashboard. The radio station's PTT is equipped with a high-quality electret microphone, a powerful 3 W speaker is responsible for the sound quality, and it is possible to connect an external speaker.

2. EquipmentMegajet MJ-300 Turbo

• Transceiver
• PTT with microphone
• Power cable with fuse
• Mounting bracket
• User guide

3. Main declared functions.

• 135 frequency channels, including holes
• Ability to work in the Russian frequency grid (shift -5 kHz)
• Built-in input signal attenuator
• Channel indication
• RX/TX signal level indicator
• Adjustable spectral noise gate
• Scan mode
• Emergency tuning to channel 9

Megajet MJ-30 radio review0 Turbo

Megajet MJ-300 Turbo is designed taking into account the climatic operating conditions in central Russia, which guarantees a long service life and stable operation. MEGAJET MJ300 Turbo has good receiver sensitivity due to modern circuitry, and this is achieved by using a separate frequency synthesizer mounted on an LC7152N chip with external digital control. This made it possible to expand the frequency range, improve the spectral purity of the signal and improve the stability of operating parameters.

The design of the Megajet 300 Turbo radio station uses a Black Matrix type liquid crystal (LCD) display with memory of the current mode and with additional backlighting. Particularly convenient when using the LCD display are the 10 mm channel number indicator numbers, black numbers on an amber background. The information panel of the LCD display displays the main functional parameters of the operating modes of the CB radio station.

MegaJet MJ-300 Turbo is based on the SAMSUNG 3P9228AZZ-QZR8 processor and uses frequency (FM) and amplitude (AM) modulation. The station is capable of operating on 135 channels in the Russian and European frequency networks and has a transmitter power of up to 8/16 W (AM/FM). The transceiver has a channel scanning mode and the ability to emergency tune to channel 9. Megajet 300 Turbo has a compact size and an informative high-contrast backlit liquid crystal display. In addition, among the distinctive features it is worth noting the built-in input signal attenuator, the ability to work in “holes” and non-volatile settings memory.

CB radio station Megajet MF-300 Turbo combines excellent functionality, good transmitter power and a low price. We can safely call this model the optimal choice for country weekend trips. Compact size, low power consumption and ease of use combined with a magnetic base antenna* make this model a good choice for everyone. The Megajet 300 Turbo radio is better suited to big city conditions, where there is a high level of interference and a large number of stations.

ATTENTION! Do not use the radio without an antenna connected to it!

Among the wide selection of antennas, you can purchase what you need in RADIOSILA stores!

Radio station MEGAJET MF-300 TURBOcan be purchased in our departments at Moscow , St. Petersburg , Yekaterinburg , Tyumen , Perm, Chelyabinsk, Ufa, Samara or order delivery to any location in Russia: Kazan,Novosibirsk , Nizhny Novgorod , Omsk , Rostov-on-Don , Volgograd , Krasnoyarsk , Saratov , Voronezh , Krasnodar , Izhevsk , Ulyanovsk , Barnaul , Irkutsk , Novokuznetsk , Orenburg , Kemerovo and other cities.

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Radio station MegaJet MJ-300

Automotive walkie-talkie MegaJet MJ-300 well known, probably, to every motorist who has a CB radio station. And no wonder. After all, it has been produced for a very long time, and many drivers have (or once had) MJ-300 in their cars. The standard of living of Russians did not always allow them to fork out for an expensive model, and many drivers chose this simple-looking and inexpensive MJ-300 radio station.

The radio station is made on the “600” technology platform (modern multifunctional radio stations are produced on this platformMJ-600 And MJ-600plus ). The longitudinal size of the case is only 125 mm, which allows you to place the radio station in the limited space of any car dashboard. The microprocessor control system for all radio modes is based on the SAMSUNG 3P9228AZZ-QZR8 central processor. The electrical circuit of the radio station is supplemented with a separate frequency synthesizer on the LC7152N chip with external digital control. This not only expanded the frequency range, but also increased the stability of operating parameters and improved the spectral purity of the generated signals.

On the front panel of the radio, to the left of the display, there are control knobs for volume/power (VR) and manual squelch (SQ). Below the display there are three buttons for switching modes: modulation type (A/F), scanning mode (SC) and turning on the emergency channel (CH9). To the right of the display are channel switching keys (UP and DN).

Features of the Megajet 300 radio:

• AM/FM mode switching
• Channel 9 Emergency Call (Grid Switching)
• Push-button control of UP/DN channels
• Frequency shift function -5 kHz
• Manual threshold squelch
• Automatic spectral noise suppressor
• Grid scan mode
• Non-volatile memory of the last used channel
• Buttons for switching operating modes
• Channel Up/Down Buttons
• Display CHANNELS/GRID/SCAN
• Indication of modes TX / FM /AM / L / M / H

Technical characteristics of the MJ-300 radio station:

Frequency range, MHz: 25.965…27.405
Number of channels: 40/120
Receiver sensitivity, µV
(12 dB S/N FM, 10 dB S/N AM) 0.3/0.5
Transmitter output power, W: 8
Modulation type: AM(90%)/FM(2 KHz)
Supply voltage, V: 13.8
Maximum current consumption, A: 2.0 max.
Dimensions, mm: 138(w) x 40(h) x 125(d)
Weight: 0.6 kg, total 1.0 kg

The radio has the ability to operate in multi-grid mode (120 channels). To switch to this mode, you must hold down the two A/F and SC buttons and turn on the radio station with the VR knob. Switching grids is done with the CH9 button. To switch the MegaJet MJ-300 radio from the European to the Russian/Polish grid, you need to hold down the A/F and CH9 buttons and turn on the radio station with the VR knob. In this case, the symbol “5” will be displayed on the screen. To return to normal mode, you need to repeat the specified operation.

To return to factory settings, you must turn off the radio and press the CH9 button to turn it on again. The radio will return to factory settings.

The MegaJet MJ-300 walkie-talkie is similar to walkie-talkiesMJ-100, MJ-200 and MJ-400 . The only slight differences are in the design and the presence or absence of some functions. We recommend this radio to drivers for working on channel 15. It is simple and reliable. With proper use it will last for more than one year.

Introduction

1. Brief technical specifications and distinctive features

2. Main features and functions

3. Controls and displays

4. Basic modes

5. Small-size LCD display

6. Installing a radio station in a car

7. Installation and configuration of a car antenna

8. Rules for using the radio station

INTRODUCTION

Thank you for purchasing the MegaJet MJ-300 car radio. The MegaJet MJ-300 radio is easy to use and will provide you with safe, fast and reliable communication. Please read these instructions carefully before use. The information presented here will help you get the best performance from your walkie talkie.

The Megajet MJ-300 radio station belongs to the class of equipment of accessible civil radio communications range.

1. SAFETY INFORMATION

The following precautions must be observed when operating, servicing, or repairing this device.

Repair and maintenance of the MegaJet MJ-300 radio must be carried out by qualified personnel in a specialized service center.
Do not make any changes to the design of the radio!
Turn off the radio before entering areas where explosive or flammable substances are present.
Do not use walkie-talkies with a damaged antenna. If a damaged antenna touches parts of the body, there is a high risk of getting burned.
To avoid electromagnetic interference or compatibility problems, turn off your radio in areas where you are required to do so, especially where there are signs reminding you to do so.
Turn off your radio before entering a blasting area.
For vehicles with airbags: Do not place the radio in the airbag deployment area or directly on the airbag covers.

Functionality of the MegaJet MJ-300 radio station

Compact design
Microprocessor SAMSUNG 3P9228AZZ-QZR8
Separate frequency synthesizer on the LC7152N chip
Front panel with small LCD display
High power speaker (8 Ohm, 3 W, square 76x76 mm)
Reliable PTT with electret microphone
Scan mode (SCAN)
Emergency tuning to channel 9 (CH9)
Possibility of connecting an external speaker

1. BRIEF TECHNICAL CHARACTERISTICS OF THE MEGAJET 300 RADIO STATION

2. KEY FEATURES AND FUNCTIONS

FUNCTIONS

• Two kinds
• SC scan button
• Channel 9 Emergency Call (switch)
• Push-button control of UP/DN channels
• Non-volatile settings memory
• Adjustable automatic noise reduction system
• Built-in input signal attenuator

CONTROL

• Volume control with power switch
• Noise reduction threshold control
• Channel up/down buttons
• Emergency call button channel 9
• Scan by channel button

LCD DISPLAY

• Display CHANNELS/GRID/SCAN
• Indication of TX / SC / / L / H modes

3. CONTROLS AND DISPLAYS

Description of controls

1. 4-pin connector for connecting a PTT (headset)
2. Power on/Volume control VOL/OFF.
3. Threshold level regulator...
4. LCD display. All current radio operating modes are displayed.
5. Button for selecting the type of modulation AM / FM (AM/FM).
6. SC scan button. This button can be used to search for a channel where there is intense radio traffic. After pressing this button, the channels are scanned upward. When a signal is detected, scanning will be paused. After reception is stopped, scanning resumes after 10 seconds. Pressing transmit will stop scanning.
7. Button for quick switching to emergency channel CH9 / switching. This button is designed to quickly switch to channel 9 in the event of an emergency. If the radio is operating in multi-grid mode, this button switches grids. When pressed for a long time (more than 1 second), the built-in attenuator is turned on to weaken the received signal. In this case, the symbols “Lo” will be displayed on the screen. When you hold down the CH9 button again, the mode is turned off, and the “Lf” symbols will be displayed on the screen.
8. Channel up button UP
9. Channel down button DN

Description of the connectors on the rear panel of the radio

SC - Scan. Indication of the “SC” sign means the receiver is operating in automatic scanning mode. To implement this function, turn on the power of the radio and set the required volume. Adjust noise reduction. Press the “SC” button and scanning will begin. “SC” will appear on the LCD display. When a channel is detected whose signal exceeds the squelch level, scanning stops and resumes again after the signal disappears, until the PTT or “SC” button is pressed.

M,L,H – in multigrid mode, displays grids C, B, D, respectively.

5 – displays the inclusion of the frequency shift mode at -5 kHz (Russian standard)

6. INSTALLING THE RADIO STATION IN THE CAR

The MegaJet MJ-300 radio station is intended for use in cars with a 12-volt battery and a grounded negative. should be sufficient both to power the radio station and for the needs of automotive electrical systems.
Before installing the radio, check that your vehicle meets this requirement.
A mounting bracket and a microphone holder are used to mount the radio in a car.

INSTALLATION LOCATION OF CB RADIO STATION

The radio station is installed in the car in such a place that its use does not create inconvenience and does not distract the driver from driving the car. The best place for this purpose is under the dashboard of the car.

Attention: When choosing a location for installing the radio, make sure that it does not interfere with the driver or impair access to vehicle controls. When laying connecting cables, observe safety requirements. If the radio or connecting cables are inconveniently positioned, you may lose control of the vehicle.

MECHANICAL WORK DURING INSTALLATION.

Step 1: Using caution, use the mounting bracket as a template to mark the mounting holes under the dash. To mark drilling locations, use an awl or other sharp tool designed for marking on metal.

Step 2: Drill two 3mm holes for each mounting plate mounting screw. Secure the bracket under the dash with the included self-tapping screws (see Figure 1). Particular care should be taken when drilling holes to avoid damaging the connecting harnesses and electronic devices located under the panel.

Fig.1. Attaching the radio using a mounting bracket.

RADIO STATION INSTALLATION.

Step 1: Insert the radio into the mounting bracket until it is aligned with the tabs (see Figure 2). Adjust the radio body to the optimal angle for ease of access.

Step 2: Attach the radio clips, making sure to provide a place to connect external cables to the rear of the radio.

INSTALLING THE MICROPHONE HOLDER.

Next to the radio station on the car dashboard, drill two holes to install the microphone holder bracket. Secure the holder with two 10 mm self-tapping screws from the kit to the radio.

CONNECTING AN EXTERNAL SPEAKER (not included in delivery).

On the back wall of the radio there is a socket for connecting an external speaker "EXT-SP". Insert the plug from the external speaker into it. This turns off the built-in speaker.

POWER CONNECTION.

Since the MegaJet MJ-300 radio station is equipped with a power supply filter to eliminate interference from the engine ignition system, it can be connected to the vehicle on-board network at any point. To reduce interference, it is better to use the wire in the form of a twisted pair.

Step 1: Disconnect the power cables from the battery terminals to prevent short circuits that may occur when connecting power to the radio.

Step 2: Securely connect the black “negative” wire from the radio directly to the vehicle body. For best operation of the radio, reliable contact with the metal of the body is required.

Step 3: Connect the red “positive” wire from the radio with the built-in fuse holder to the fuse block (“cigarette lighter” or directly to the positive terminal of the battery). Typically, the most convenient point to connect the radio is the fuse box. You can connect the power cable to the ignition switch contacts, in which case the radio will turn off automatically when the ignition is turned off, which will prevent accidental battery discharge.

Step 4: Reconnect the power cables to the battery terminals. Connect the power cord plug to the radio cable connector.

7. INSTALLING AND CONFIGURING A CAR ANTENNA

In general, there are two types of antennas for mobile CB radios - a full-length 1/4 wavelength whip (2.75 m) and a short matched whip antenna (from 0.5 to 1.9 m). Due to the large length of full-size antennas on cars, shortened antennas are mainly used in various designs with mounting through a hole in the roof, on a bracket behind the gutter flange or on a magnetic base (see Fig. 3).

Rice. 3. Typical installation locations for car antennas.

Antennas on a magnetic base have the advantage that they can be easily retracted inside the car when parked, and the strength of the magnet ensures its secure attachment during shaking and high-speed driving.

Its radiation pattern depends on where the antenna is installed. When installing the antenna in the middle of the roof, the radiation pattern approaches circular. If the antenna is installed on the right edge of the roof, then its maximum gain will be directed to the left of the vehicle axis. When placing the antenna on the rear trunk, its pattern will face forward.

In Fig. Figure 3 shows five typical installation locations for a car antenna: (1) rear bumper, (2) rear trunk lid, (3) water drain flange, (4) hood, (5) roof.
To receive qualified advice regarding the choice of antenna type and location of its installation, contact your retailer.

The installed car antenna must be tuned to resonance at a medium frequency. To configure and periodically monitor the antenna and antenna cable, a meter is used, which is connected to the circuit between the radio station and the antenna cable using a separate adapter cable of minimum length. Different types of antennas are configured in different ways, so you should read the instructions. As a rule, tuning an antenna that has reliable galvanic (or capacitive - across the entire area of ​​the magnet) contact with the conducting underlying surface (the area of ​​the cabin roof) at its location point is carried out by decreasing or increasing the length of the pin. Try to achieve a minimum SWR (unity ideally) in the middle of your chosen frequency range (for example, between the two most frequently used channels). And if, at the same time, at the edges of the “working” range it is possible to obtain an SWR of no more than 1.5, then your choice of channels is correct and the antenna is tuned perfectly.

Carefully follow the manufacturer's antenna installation instructions.

Attention! Never turn on the radio station for transmission, even for a short time, with an untuned antenna or a “out-of-tune” antenna, when reliable electrical contact of the cable braid and the antenna “ground” with the conductive underlying surface at the antenna location is lost. This can lead to damage to the radio and electrical equipment of your car!

8. RULES FOR USE OF THE RADIO STATION

• Turn on the radio station by rotating the “VOL/OFF” knob clockwise. Set the required sound volume.
• Adjust the noise reduction threshold using the “SQ” control in accordance with the instructions in this manual.
• Select the desired channel using the UP/DN channel buttons.

Note: If you are not changing channels, please note that the emergency channel mode may be enabled. This mode is disabled by pressing the CH9 “Channel 9” emergency button.

TRANSMISSION MODE.

Press and hold the “PTT” switch on the microphone body. Hold the microphone body 5 cm from your mouth and speak in a normal, intelligible voice.

RECEPTION MODE.

Simply release the PTT switch and listen to your correspondent, using the volume and noise reduction controls to achieve the best sound quality.

This station is designed to solve completely different problems. Apparently, in this way, the RKK company decided to divide the market and earn even more money.

And I dare say they succeeded. The station is quite interesting, it is not designed to work in AM, although it can work in this modulation. Her path is frequency modulation, or FM.
So, if you are a CB taxi driver, or just use the band mainly in FM, and don't want to spend a lot of money on a walkie-talkie, this station is for you. In the harsh operating conditions of taxi fleets, which is where the MegaJet MJ-300 is most often used, the station showed its best side. It is extremely simple and reliable. Now, let's take a closer look at it.

The station is supplied in a glossy silver cardboard box. Like MegaJet, the cardboard is thin but durable.

The station is well packed. Inside the box there is a plastic insert that absorbs shock and is designed to divide the space for transportation.

The kit includes the radio station itself, instructions in English, a headset, a mounting bracket and fasteners.

Appearance
In appearance, the station is very reminiscent of MegaJet, the general pedigree can be traced well. The dimensions of the case remain the same.


The front panel is made of plastic. The plastic looks cheaper than . It is more slippery and glossy.


The case consists of a chassis to which all internal electronics are attached, two metal covers, top and bottom. Each cover is attached separately using 4 screws. As I already wrote in, this is not very good, because at high volumes such a design will rattle.


Ergonomics have changed. Now it is more convenient to use the station. The volume control and noise reduction control knobs are still nearby, but they are now located vertically, which, in my opinion, is more convenient. The handles rotate with little effort, but softly and without jamming. On the front panel there are buttons for switching channels, a button for changing modulation, a button for turning on channel scanning, this mode has been added here. The CH9 button performs many functions, which are discussed below.
The display, like the one, has a pleasant amber backlight. The indication completely repeats the indication of its younger brother. The channel number, grid letter, modulation and mode 0/5 are displayed here.


The display has the same disadvantages. It is clearly visible only from the front and above. You can't see anything from below at all.


The headset connector is modern 4-pin and looks reliable.


The headset itself is very simple, like the one, it only has a microphone and a push-to-talk button.


The headset wire is also very soft and should not stiffen in the cold.

At the back of the station there is a connector for connecting an antenna, a jack for connecting an external speaker and a power cable.


There is no quick disconnect connector on the wire.

The speaker is located on the bottom cover, like almost all civilian radio stations. There is also a marking plate with the serial number.

Functions
In general, the station repeats its younger brother in functions, but there are some features. The station has 40 channels in normal mode, and 120 channels in extended mode. AM/FM modulation, operation in zeros and fives (0/5), in addition, there is a channel scanning function, which can be useful in unfamiliar areas, the function is displayed on a separate SC button. The main distinguishing feature is the presence of automatic noise reduction with manual adjustment. If market sellers tell you that the station has a threshold noise suppressor, do not believe it! A real spectrum monitor, but with the ability to adjust, which is a plus.

To switch the station to multi-grid mode, you need to turn off the station, hold down the A/F button and turn on the station. After a couple of seconds, you need to release the button and the message EP will appear on the display, which means that we have switched to multi-grid mode. Grids are switched using the CH9 button. The grid correspondence is as follows: M – C, H – D, L – B. A total of 120 channels. The station has a built-in attenuator, which can be turned on by holding down the CH9 button. The letters Lo (local on) will appear on the screen, indicating that the attenuator is on. To turn it off, we do the same thing and LF (local off) should appear on the screen. This feature can be useful in noisy airwaves. To switch between fives and zeros, you need to turn off the station, hold down the A/F and CH9 keys and turn on the radio. The buttons need to be released after a couple of seconds. The number 5 will appear on the display indicating that the station has switched to zeros. The scanning function is activated by the SC button. Scanning will continue until the squelch opens.

Inside
The station is made on a printed circuit board made of green PCB. The installation was neat, no soldering flaws were noticed. Not washed flux either.


And the one in the photographs was left by yours truly during revision. I use no-clean gel flux. The components on the board are not labeled, which may make it difficult to find the right element.


Some of the parts are not soldered, which suggests that this printed circuit board is also used for the production of other radio stations. The output stage is made according to the classical scheme, using 2SC2314 and 2SC2078.


The overall impression of the filling is positive.

Stated characteristics

Frequency range: 26.965…27.855 MHz
Number of channels: 120 AM/FM
Transmitter power: 10 W
Power: 13.8 V
Dimensions: 138(w) x 40(h) x 125(d)
Weight: 600 gr

Modifications
About improvements to MJ-300.

Bottom line
MJ-300, like , is not suitable for all tasks. They share the market harmoniously and should be used in their intended niches. Due to the fact that the station has only one noise suppressor, an automatic one, using it in the truckers channel (15AM) is not advisable, since it will simply irritate you with its constant triggering for no reason. If they offer it to you for Channel 15, don’t take it! For these purposes, a threshold noise suppressor is most suitable, as, for example, in the MJ-100. The path of the MJ-300 is either work in a taxi, or use for other tasks where frequency modulation is used.