Product overview
The RadioMaster ER12 PWM - Dual-Band GEMINI and GEMINI-X Receiver serves larger fixed-wing aircraft with multiple servos and higher current loads. Its ExpressLRS architecture combines two Semtech LR1121 transceivers with operation on 2.4 GHz and Sub-G 900 MHz. Twelve PWM channels provide servo outputs, while amplified signals help support long leads, extension cables and larger high-torque servos. Serial integration includes CRSF / SBUS output and a dedicated 4-pin JST-GH locking UART/CRSF connector for telemetry devices and other serial peripherals.
The receiver occupies 51.0 × 37.6 × 14.5 mm and weighs 22.5 g without its antenna. An injection-molded housing surrounds the electronics, with serviceable MMCX antenna connections and a specified 25 cm high-sensitivity antenna. Three independent ADC channels monitor EXT-V, receiver supply and XT30 input voltages simultaneously, with respective upper limits of 70V, 12V and 12V. Wi-Fi and WebUI allow configuration and firmware updates without opening the housing. The firmware requirement is ExpressLRS version 4.1.0 or higher.
The supplied receiver package includes two 2.4GHz antennas, two dual-band antennas, a Type-B voltage telemetry cable, an ELRS RX SBUS cable and a CRSF cable. Power integration requires particular care: XT30 passes its input voltage directly to the receiver and PWM power rail. Servos must match that voltage, and 2S LiPo/Li-ion systems require HV-rated servos. Standard 5V servos require a regulated 5V supply or the standard servo power input pins. When XT30 powers the receiver and servos, disconnect the ESC’s 5V/BEC wire to prevent back-feeding and possible damage.
Specifications
| Specification | Value & conditions |
|---|---|
| Product | RadioMaster ER12 PWM - Dual-Band GEMINI and GEMINI-X Receiver |
| Intended application | PWM receiver for large fixed-wing aircraft with multiple servos and higher current loads. |
| RF architecture | Dual Semtech LR1121 transceivers with dual-band Gemini X RF architecture operating on 2.4 GHz and Sub-G 900 MHz. |
| Input voltage | DC 5.0 – 12.0V |
| Wireless protocol | ExpressLRS |
| Output channels | 12CH PWM |
| PWM and serial integration | Full 12-channel PWM output with dedicated bidirectional UART and serial interfaces for system integration and expansion. |
| Serial output | CRSF / SBUS |
| Telemetry power | Up to 100mWAdjustable via LUA. |
| EXT-V voltage detection range | DC 4.0 – 70V |
| Bus interface | CRSF |
| Antenna | 25 cm high-sensitivity, MMCX connector |
| Weight | 22.5 gWithout antenna. |
| Dimensions | 51.0 × 37.6 × 14.5 mm |
| Firmware target | RadioMaster Dual 2.4GHz/900MHz Receiver |
| Device name | ER12 Dual Band True Diversity + 12×PWM RX |
| ELRS firmware requirement | Requires version 4.1.0 or Higher |
| Independent voltage telemetry | Up to three power sources: EXT-V up to 70V, receiver supply voltage (V-PWM) up to 12V, and XT30 input voltage up to 12V.Simultaneous monitoring using dedicated ADC channels. |
| UART connector | Dedicated 4-pin JST-GH locking UART/CRSF port for telemetry devices and serial peripherals. |
| PWM signal amplification | Amplified PWM outputs support signal delivery over long servo wiring and improve compatibility with larger, high-torque servos.Long servo leads, extension cables and larger high-torque servos. |
| Housing and antenna connections | Injection-molded housing, serviceable MMCX antenna connectors and a PCB layout intended to reduce interference. |
| Wireless configuration and updates | Wi-Fi and WebUI support settings changes and firmware updates without disassembly. |
| XT30 power routing | XT30 supplies direct battery voltage to the receiver and PWM power rail; output voltage matches input voltage, requiring servos rated for that voltage.When powered through XT30. |
| Servo power requirements | 2S LiPo/Li-ion systems require HV-rated servos. Standard 5V servos require a regulated 5V supply or the standard servo power input pins.High-voltage systems using 2S LiPo/Li-ion batteries, or installations using standard 5V servos. |
| ESC BEC wiring requirement | Disconnect the ESC’s 5V/BEC wire to prevent back-feeding and possible damage.When XT30 powers the receiver and servos. |
| EXT-V connection | 2-pin JST-GH connector; connect the red wire to the battery or ESC positive (+) terminal. |
| Supplied configuration | 1 ER12 PWM receiver, 2 2.4GHz antennas, 2 dual-band antennas, 1 Type-B voltage telemetry cable, 1 ELRS RX SBUS cable and 1 CRSF cable. |
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