RadioMaster ER3 PRO PWM - Dual-Band GEMINI and GEMINI-X Receiver
by RadioMaster

Because the FCC is currently preventing new certifications for foreign-made UAS components, we currently cannot import or sell these in the US. If they operated within the amateur bands, we could import them under the current authorization for amateur radio devices. ELRS does not currently support this. We recommend all US customers comment on the ELRS GitHub feature request and also give the request an upvote.
https://github.com/ExpressLRS/ExpressLRS/discussions/3725
Until these are able to be locked on amateur bands, we will be unable to sell them. 

The RadioMaster ER3 PRO PWM - Dual-Band GEMINI and GEMINI-X Receiver is a compact, high-performance ExpressLRS receiver engineered for space-constrained fixed-wing aircraft, glider fuselages, and surface vehicles requiring uncompromised link reliability. Powered by dual Semtech LR1121 transceivers operating on GEMINI-X RF architecture, the ER3 PRO simultaneously utilizes both 2.4GHz and Sub-G 900MHz frequency bands to provide true dual-band diversity and exceptional interference immunity.

Despite its streamlined form factor, the ER3 PRO acts as a versatile control hub with 3 amplified PWM channels, CRSF and SBUS serial outputs, and an external locking UART port for telemetry and system expansion. It features independent multi-source voltage telemetry with dedicated ADC channels for monitoring both receiver supply voltage (V-PWM up to 12V) and main flight batteries (EXT-V up to 70V). Housed in a durable injection-molded casing with secure MMCX antenna connectors, it transmits up to 100mW of telemetry power for maximum feedback range.

Key Features

• Dual-Band GEMINI-X RF Architecture: Simultaneously operates across 2.4GHz and Sub-G 900MHz bands via dual LR1121 transceivers for true diversity and link stability.

• 3 Amplified PWM Outputs + Serial Support: Delivers 3 direct servo PWM channels alongside CRSF and SBUS serial protocols for flexible airframe integration.

• Up to 100mW Telemetry Power: Transmits real-time link and telemetry data back to the transmitter with adjustable output power up to 100mW via ExpressLRS LUA script.

• Dual-Source Voltage Telemetry: Dedicated ADC channels independently monitor receiver supply/ESC BEC voltage (V-PWM up to 12V) and external main battery packs (EXT-V up to 70V).

• Locking Connectors for High Vibration: Built-in locking JST connectors on external UART and EXT-V telemetry ports prevent unintended disconnections.

• Secure MMCX Antenna Connectors: Heavy-duty MMCX ports allow easy replacement and maintenance of the included high-sensitivity antennas.

• Wi-Fi WebUI & Wireless Configuration: Supports direct wireless configuration, parameter tuning, and firmware updates without disassembling the receiver from tight bays.

Technical Specifications

• Brand / Manufacturer: RadioMaster

• Model Identifier: ER3 PRO PWM Dual-Band GEMINI and GEMINI-X Receiver

• RF Chipset: Dual Semtech LR1121 Transceivers

• Wireless Protocol: ExpressLRS (Requires ExpressLRS v4.1.0 or higher)

• RF Architecture: Dual-Band GEMINI-X (2.4GHz + Sub-G 900MHz)

• Output Channels: 3x PWM Channels

• Serial Protocol Support: CRSF / SBUS

• Input Voltage Range: DC 5.0V – 12.0V

• EXT-V Detection Range: DC 4.0V – 70.0V (2-Pin JST-GH Port)

• V-PWM Detection Range: Up to 12.0V DC

• Telemetry RF Output Power: Up to 100mW (Configurable via LUA script)

• Bus Interface: CRSF

• Antenna Connectors: MMCX (Secure, detachable)

• Antenna Array: 25cm High-Sensitivity Antennas

• Firmware Device Target: RadioMaster Dual 2.4GHz/900MHz Receiver

• Device Target Name: ER3Pro Dual Band True Diversity + 3xPWM RX

• Dimensions: 49.2 mm × 26.8 mm × 13.0 mm

• Net Weight: 13.5 grams (without antennas)

What Is Included

• (1) RadioMaster ER3 PRO PWM Dual-Band GEMINI-X Receiver

• (2) 2.4GHz High-Sensitivity Antennas (MMCX)

• (2) Dual-Band High-Sensitivity Antennas (MMCX)

• (1) External Voltage Telemetry Cable (EXT-V Type-B)

• (1) CRSF Serial Connection Cable

• (1) ELRS RX to SBUS Connection Cable