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

The ER3 PRO is a compact receiver designed for installations where space is limited but link reliability and system access remain important. Despite its small footprint, it retains a full-featured RF and telemetry interface, making it well suited for clean, space-constrained builds.

At its core is the ExpressLRS system, built around dual Semtech LR1121 transceivers and a dual-band Gemini X RF architecture operating on both 2.4 GHz and Sub-G 900 MHz. Combined with up to 100mW telemetry output power, it provides a stable control link and enhanced telemetry performance for applications where reliable telemetry data is important.

With 3 PWM outputs, serial protocol support, and dual independent voltage telemetry channels, the ER3 PRO integrates easily into a wide range of aircraft and vehicle platforms. Dedicated ADC channels independently monitor receiver supply voltage (V-PWM) (up to 12V) and EXT-V (up to 70V), providing accurate telemetry for each voltage source. Locking connectors on the UART and EXT-V telemetry ports help ensure secure, reliable connections in demanding operating environments.

Serviceability is built in. Robust MMCX antenna connectors provide secure attachment and easy replacement, while the durable injection-molded housing delivers long-term protection in a compact form factor.

Features:

ExpressLRS Performance: Low latency, high reliability, and excellent link quality with flexible configuration options.

Dual-Band Gemini X (2.4GHz + Sub-G 900MHz): Utilizes both frequency bands to provide enhanced link reliability across a wide range of operating environments.

Up to 100mW Telemetry Output:  Increased telemetry output power for improved data reliability and range.

3 PWM Outputs + Serial Support: Compact PWM output with CRSF and SBUS options.

External UART Port (Locking Connector): Dedicated interface for telemetry, external devices, and system expansion.

Independent Multi-Source Voltage Telemetry: Monitor up to two power sources simultaneously using dedicated ADC channels: EXT-V (up to 70V), receiver supply voltage (V-PWM) (up to 12V).

MMCX Antenna Connectors: Durable, replaceable antennas with a secure connection.

Wi-Fi Updates & WebUI: Configure and update directly without disassembly.

Durable Injection-Molded Housing: Compact, protective enclosure for long-term reliability.

Application: A compact, full-featured receiver for models that require advanced RF performance, telemetry, and connectivity in a space-efficient package.

Compatibility: Compatible with all ExpressLRS transmitters and modules, including radios with built-in ELRS.

⚠️ Power Input & Voltage Notice

EXT-V Telemetry Input:
The maximum input voltage for the EXT-V external voltage telemetry reading is 70V. Do not exceed 70V, as this may damage the receiver.

The EXT-V input is accessed through the 2-pin JST-GH connector. Connect the red wire to the positive (+) terminal of the battery or ESC. The ER3 PRO provides independent ADC channels for EXT-V and receiver supply voltage (V-PWM).

Servo Power:
Ensure the ESC’s BEC can provide sufficient current for the servos being used. For high-voltage, high-torque servos, a 2S 7.4V battery or a suitable high-current UBEC is recommended.

Specification

Item: ER3 PRO PWM - Dual-Band GEMINI and GEMINI-X Receiver

Input Voltage: DC 5.0 – 12.0V

Wireless Protocol: ExpressLRS

Output Channels: 3CH PWM

Serial Output: CRSF / SBUS

Telemetry Power: Up to 100mW (adjustable via LUA)

Voltage Detection Range (EXT-V): DC 4.0 – 70V

Bus Interface: CRSF

Antenna: 25 cm high-sensitivity, MMCX connector

Weight: 13.5 g (without antenna)

Dimensions: 49.2 × 26.8 × 13.0 mm

Firmware Target: RadioMaster Dual 2.4GHz/900MHz Receiver

Device Name: ER3Pro Dual Band True Diversity + 3×PWM RX

ELRS FW Version: Requires version 4.1.0 or Higher

Package Includes

1 * ER3PRO PWM - Dual-Band GEMINI and GEMINI-X Receiver

2 * 2.4GHz Antennas

2 * Dual-Band Antennas

1 * Voltage Telemetry Cable (Type-B)

1 * CRSF Cable

1 * ELRS RX SBUS Cable