RadioMaster ER12 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 ER12 PWM - Dual-Band GEMINI and GEMINI-X Receiver is a high-performance ExpressLRS receiver purpose-built for large-scale fixed-wing aircraft, demanding aerobatic models, and giant-scale gliders. Leveraging advanced GEMINI-X RF architecture, the ER12 concurrently operates on both 2.4GHz and Sub-G 900MHz frequencies to provide unparalleled signal reliability, long-range link penetration, and extreme interference rejection in congested RF environments.

The ER12 acts as a central distribution hub for complex RC planes, featuring 12 fully amplified PWM output channels that maintain robust signal integrity over long servo extensions. A dedicated XT30 power input connector delivers stable, high-current power directly to large or high-torque servos without straining the flight controller or receiver circuitry. With independent multi-source voltage telemetry—capable of monitoring the XT30 input, receiver PWM rail, and main flight batteries up to 70V—the ER12 gives pilots complete, real-time awareness of their aircraft’s power systems.

Key Features

• Dual-Band GEMINI-X RF System: Combines 2.4GHz and Sub-G 900MHz ExpressLRS technologies simultaneously for true diversity reception and maximum link stability.

• 12 Amplified PWM Outputs: Drives up to 12 servos directly, utilizing amplified signal outputs to prevent signal degradation across long servo leads.

• Dedicated XT30 Power Input: Provides a robust, high-current power delivery path (up to 12V) specifically designed to feed power-hungry multi-servo setups.

• Multi-Source Voltage Telemetry: Three independent ADC channels allow real-time monitoring of EXT-V (up to 70V), V-PWM/Receiver supply (up to 12V), and XT30 input (up to 12V).

• High-Power Adjustable Telemetry: Capable of outputting up to 100mW of telemetry power (adjustable via ELRS LUA script) for long-range data return.

• External UART & Serial Support: Features a dedicated external UART port for convenient connectivity, supporting CRSF and SBUS output for flight controllers and expansion modules.

• Wi-Fi Updates & WebUI: Allows for fast, wireless firmware flashing and configuration without removing the receiver from buried airframe installations.

• Rugged Injection-Molded Housing: The hard plastic enclosure and secure MMCX antenna connectors offer superior durability against crash impacts and airframe vibrations.

Technical Specifications

• Brand / Manufacturer: RadioMaster

• Model Identifier: ER12 PWM Dual-Band GEMINI-X Receiver

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

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

• Output Channels: 12x PWM Channels

• Serial Protocol Support: CRSF / SBUS

• Input Voltage Range: 5.0V – 12.0V DC

• XT30 Input Voltage Detection Range: Up to 12.0V DC

• V-PWM (Receiver Supply) Detection Range: Up to 12.0V DC

• EXT-V (External Voltage) Detection Range: 4.0V – 70.0V DC

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

• Antenna Connectors: MMCX (Secure, detachable)

• Antenna Type: 25cm High-Sensitivity Antennas

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

• Dimensions: 51.0 mm × 37.6 mm × 14.5 mm

• Net Weight: 22.5 grams (without antennas)

What Is Included

• (1) RadioMaster ER12 PWM Dual-Band GEMINI-X Receiver

• (2) 2.4GHz High-Sensitivity Antennas

• (2) Dual-Band High-Sensitivity Antennas

• (1) Voltage Telemetry Cable (Type-B)

• (1) CRSF Serial Cable

• (1) ELRS RX to SBUS Cable