Product Overview: 
The ESP138D supports Bluetooth 5.0 dual-mode transmission and reception, featuring a 2.4-inch touchscreen, numeric keypad, high-capacity battery, and aluminum alloy body, balancing professional reception with portability. In terms of system, it adopts a dual architecture of TEF6686 system (open-source project by Megatron) and ESP32+SI4732 system, perfectly balancing 'high-fidelity radio reception' and 'professional radio exploration.' Compared to the ESP138, it adds a built-in decoding board and an official activation code for H-RADIO firmware, supporting decoding and more functions.

Product Features:
1. Dual System Reception: The ESP138D is a hardware-level dual-architecture radio, employing the TEF6686 system (open-source DSP algorithm) and the ESP32-SI4732 system (full-band coverage) operating independently. Switching between systems is easy with a single click of the power button while the radio is powered on. Note: Theoretically, both modes support firmware flashing, but it is recommended to use the factory default firmware; otherwise, malfunctions may occur.
2. TEF6686 System: The TEF6686 system supports FM/LW/MW/SW bands, DSP noise reduction algorithms (CEQ, EMS, iMS, and PACS), and full RDSs data display, specializing in high-fidelity broadcast reception.
3. SI4732 System: Through hardware optimization and official cooperation, the ESP138D includes built-in H-RADIO official firmware and activation code. The SI4732 system supports full-mode modulation and demodulation: AM, FM, LSB, USB, CW (Morse code) and aviation bands (AIR 118-138MHz). It supports ATT attenuation, AGC gain control, bandwidth (BANDW) level switching, single-sideband fine tuning (BFO), and digital decoding: RTTY (45.45/50/75 baud), PSK (BPSK31/63), Feld-Hell, FT4, FT8, CW; firmware version is 4.21 air beta.
4. Supports dual Bluetooth modes: Users can connect their mobile phone to the radio via Bluetooth, using the radio as a Bluetooth speaker. Radio broadcasts or audio received on the radio can also be transmitted via Bluetooth to Bluetooth headphones or speakers.
5. Powerful configuration: The speaker uses a 40mm long-stroke full-range speaker, delivering powerful bass and clear treble. It features a built-in 820mm extra-long telescopic antenna and a 3.5mm external antenna connector at the bottom. A numeric keypad allows for quick frequency input, while a rotary knob provides tuning. Note: When using the touchscreen with the SI4732 system, the physical numeric keypad and menu button will be disabled (Bluetooth/volume buttons function normally).

Frequency:
TEF6686 Mode:
Coverages FM (65-108MHz) / LW (144-513kHz) / MW (520-1720kHz) / SW (1700-27000kHz), does not support AIR Band and SSB.
SI4732 Mode:
Coverages LW (153-500kHz) / MW (520-1710kHz) / SW (1730-30000kHz) / FM (64-108MHz) / SSB (1730-30000kHz) / AIR (50-200MHz, natively supports 118-138MHz).
Supports Aviation Band (AIR) and Single Sideband (SSB), no additional equipment required.

Specifications:
Main Control Unit: ESP32-WROOM-32U
Bluetooth: JL High-Performance Chip
Decoder Board: Built-in
Screen: 2.4-inch IPS Touchscreen (320x240)
Speaker: 40mm Full-Range Speaker
Antenna: Built-in 820mm Telescopic Antenna
External Antenna Interface: 3.5mm External Antenna Interface
Battery: 3.7V / 2500mAh Polymer Lithium Battery (Package is not includes battery)

Interface: Type-C (5V/2A Charging, Supports Data Upgrades)
Casing Material: Aluminum Alloy
Dimensions: 120×63×25mm (excluding antenna)
Weight: Approx. 350g

Note: To maintain maximum firmware compatibility, the H-RADIO firmware author has developed many features within the firmware; however, not all versions of the radio support all of these features. This unit does not support Hi-Z/50Ω switching + LNA preamplifier. If function buttons on some pages are grayed out, it indicates that this unit does not support them.

Package Included:
1 x Radio
1 x Type-C charging cable