V4B Upgrade Contents:

1. A shielding cover is added to the Si4732 receiving part to suppress electromagnetic interference; an ESD protection chip is added at the antenna input end to ensure safety.

2. The Hi-Z circuit is moved to the front end of the antenna path and a more stable VCC_RADIO power supply is adopted to retain signal resonance and reduce noise.

3. A function of using a wired headset as the FM antenna has been newly added (the headset is not included in the shipping list. Please have the buyer prepare it themselves; it should be used in an environment with a strong FM signal and the headset cable should be relatively long for better performance).

4. The left and right channels have been swapped; at the same time, the parameters of the power amplifier and the speaker have been re-adjusted to improve the sound quality.

5. More expensive and superior components have been replaced: a more sturdy and durable telescopic antenna, and a more comfortable and anti-slip knob cap.

6. The motherboard hardware directly supports the H.J.Berndt firmware. No additional soldering or modification of the motherboard is required, and the official firmware will be pre-installed by default. After receiving the device, you need to manually update to the H.J.Berndt version of the firmware. The firmware developed by H.J.Berndt includes functions such as RTTY/CW decoding.

7. Since 2026, the hardware of this radio has been upgraded to the V4B version. This version can directly support the H.J.Berndt firmware without additional soldering or modification of the motherboard. However, it should be noted that the radio will be pre-installed with the official firmware by default instead of the H.J.Berndt firmware. After receiving the device, you need to manually update to the H.J.Berndt version of the firmware. The firmware developed by H.J.Berndt includes functions such as RTTY/CW decoding.

Basic functions:

1. Utilizes ESP32-S3 as the main control unit and SI4732 DSP chip. Supports broadcasting across all bands, LSB USB AM FM modes, and includes AGC/ATT functions.

2. Equipped with a 1.9-inch IPS high-definition color screen, allowing for adjustment of screen backlight brightness and displaying battery level.

3. Features a 1W power speaker with clear and pleasant sound quality.

4. Supports firmware upgrade to the latest version. The factory-preinstalled firmware version is at least VER.2.3.1 (Due to frequent firmware updates, please update to the latest firmware as soon as you receive it according to the instructions to maintain the latest usage experience.)

5. Includes an ear amplifier circuit, ensuring loud volume when listening with headphones.

6. Features a Hi-Z circuit to enhance weak signal resolution.

7. Continues to use the original ESP32 module (ESP32-S3-WROOM-1-N16R8), rather than counterfeit modules used by other cloned models.

Regarding the hardware version:

1. The mainboards of all currently available AMNVOLT V4 versions of the ATS MINI radios on the market are actually V4B.

2. We have not changed the printed "V4" on the casing and the mainboard, but in fact, the mainboards have all been upgraded to the V4B version. Please rest assured to purchase and use it.

3. How to identify if the radio you receive is the V4B version: Ignore the printed words and directly check the reference diagram. If the corresponding position matches this diagram, it is V4B.

Specifications:

Brand: AMNVOLT

Model (Hardware Version): V4B

Case Material: Your choice of Metal or ABS Plastic injection molding.

Main Controller: ESP-32-S3

Operating Modes: FM / AM / LSB / USB (Note: Does not support Air Band)

Reception Bands: HF / SW / MW / VHF

Frequency Range: LW, MW, SW (150kHz - 30MHz), VHF (64-108MHz)

Screen: 1.9-inch, 170*320 resolution

Screen Brightness: 32~255 levels, adjustable

Charging Port: TYPE-C (Cannot use fast chargers for charging)

Audio Jack: 3.5mm 3-pin stereo

Antenna Connector: SMA-KE (Female, Inner Hole)

Battery Capacity: 800mAh

Package List:

1 x AMNVOLT V4B Radio

2 x Antennas (Telescopic Whip Antenna / Rotatable Loop Antenna)

Please note when purchasing：

1. Headphones are NOT included in the package. The headphones shown in pictures are for demonstrating the FM antenna function only. Please prepare your own headphones!

2. If you select the metal case version, please be aware that the aluminum material provides some shielding against wireless electromagnetic signals. While this improves reception against interference, it can also weaken the Wi-Fi connection strength. Please consider this before purchasing.