Product overview
The RadioMaster ER3 PRO PWM - Dual-Band GEMINI and GEMINI-X Receiver provides control reception and telemetry for aircraft and vehicle installations with limited space. Its ExpressLRS architecture uses two Semtech LR1121 transceivers and operates on 2.4 GHz and Sub-G 900 MHz. Three PWM outputs are complemented by CRSF and SBUS serial output options. The receiver requires ExpressLRS firmware version 4.1.0 or higher, with telemetry transmission adjustable through LUA to a maximum of 100mW.
The injection-molded enclosure measures 49.2 × 26.8 × 13.0 mm, and receiver weight is 13.5 g without the antenna. Replaceable antennas use MMCX connectors, while locking UART and EXT-V connectors support secure integration. The external UART provides access for telemetry, external devices and expansion. Separate ADC channels monitor receiver supply voltage up to 12V and external voltage up to 70V simultaneously. Wi-Fi updates and the WebUI allow configuration and firmware maintenance without opening the enclosure.
The supplied configuration comprises one receiver, two 2.4GHz antennas, two dual-band antennas, a Type-B voltage telemetry cable, a CRSF cable and an ELRS RX SBUS cable. Receiver power input is DC 5.0–12.0V; the separate EXT-V sensing input covers DC 4.0–70V and must not exceed 70V because receiver damage may result. Servo installations require sufficient current from the ESC’s BEC. For high-voltage, high-torque servos, a 2S 7.4V battery or suitable high-current UBEC is recommended.
Specifications
| Specification | Value & conditions |
|---|---|
| Product | RadioMaster ER3 PRO PWM - Dual-Band GEMINI and GEMINI-X Receiver |
| Intended installation | Compact receiver for installations with limited space. |
| RF architecture | Dual Semtech LR1121 transceivers; dual-band Gemini X operating on 2.4 GHz and Sub-G 900 MHz. |
| 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)Adjustable via LUA. |
| Voltage detection range | DC 4.0 – 70VEXT-V external voltage telemetry input. |
| Bus interface | CRSF |
| Antenna | 25 cm high-sensitivity, MMCX connector |
| Weight | 13.5 g (without antenna)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 firmware requirement | Requires version 4.1.0 or Higher |
| Independent voltage telemetry | Simultaneous monitoring of up to two power sources through dedicated ADC channels.EXT-V up to 70V; receiver supply voltage (V-PWM) up to 12V. |
| External UART | Locking external UART connector for telemetry, external devices and system expansion. |
| Telemetry port retention | Locking connectors on UART and EXT-V telemetry ports. |
| Housing | Compact, protective injection-molded housing. |
| Antenna serviceability | Replaceable antennas attached through MMCX connectors. |
| Configuration and updates | Wi-Fi updates and WebUI configuration without disassembly. |
| Radio integration | Supports integration with ExpressLRS transmitters, modules and radios with built-in ELRS.ExpressLRS transmitters and modules, including radios with built-in ELRS. |
| EXT-V voltage limit | Maximum 70V; exceeding 70V may damage the receiver.EXT-V external voltage telemetry input. |
| EXT-V wiring | 2-pin JST-GH connector; red wire connects to the battery or ESC positive (+) terminal.EXT-V telemetry connection. |
| Servo power provision | ESC BEC must supply sufficient servo current; a 2S 7.4V battery or suitable high-current UBEC is recommended for high-voltage, high-torque servos.For high-voltage, high-torque servos. |
| Receiver and antennas included | 1 ER3PRO PWM receiver, 2 × 2.4GHz antennas and 2 × dual-band antennas.Supplied package. |
| Cables included | 1 voltage telemetry cable (Type-B), 1 CRSF cable and 1 ELRS RX SBUS cable.Supplied package. |
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