GEPRC ELRS 915M/2.4G C3 Gemini Xrossband Receiver, ExpressLRS Dual-Band LR1121x2 ESP32-C3

Overview

The GEPRC ELRS 915M/2.4G C3 Gemini Xrossband Receiver is an ExpressLRS-based dual-band receiver system built around Semtech LR1121 (3rd generation RF) and an ESP32-C3 chip, supporting 150-960MHz (sub-GHz) and 2.4GHz for advanced dual-band communication. It supports up to 1000Hz (FSK) refresh rate and allows operation in 915M Gemini, 2.4G Gemini, and 915M+2.4G dual-band modes (915M+2.4G dual-band mode requires a GeminiX TX / GemX TX). In dual-band mode, it can communicate separately on 915MHz and 2.4GHz for improved anti-interference.

With a built-in TCXO for stable operation in extreme temperatures, up to 100mW telemetry (TLM) power, a built-in WiFi antenna for firmware upgrades via Wi-Fi, and an SH1.0 connector, it is designed for compact and efficient installation. The receiver can also be used as a TX with 100mW output by selecting the RX_AS_TX option during firmware setup and using a custom JR bay modification kit (ESP32-C3 receiver must select version 3.6 to be used as TX).

Key Features

• Advanced ExpressLRS 915M/2.4G dual-frequency system
• Based on Semtech LR1121 RF chip; supports 150-960MHz (sub-GHz) and 2.4GHz
• Dual LR1121 chips; ESP32-C3 chip
• Operating modes: 915M Gemini, 2.4G Gemini, 915M+2.4G dual-band
• Integrated TCXO for stable frequency performance across temperature changes
• Telemetry power up to 100mW
• Refresh rate: 25Hz-1000Hz (LoRa, FSK)
• Firmware upgrade via Wi-Fi (built-in WiFi antenna)
• RGB light indicates status
• Omni-directional signal reception
• Custom 915M+2.4G dual-band T-antenna for reception at both frequencies (no antenna swap needed when switching bands)

For setup help, wiring questions, or firmware guidance, contact support@rcdrone.top or visit https://rcdrone.top/.

Specifications

Wiring & Installation Notes

• RX wiring (SH1.0): GND, 5V, TX, RX. Connect RX TX to FC RX, and RX RX to FC TX.
• Betaflight standard wiring sequence differs from the ELRS standard. Always check the connection order between FC and RX before plugging in the connector to avoid RX damage caused by reversed polarity.
• Single-frequency antenna installation:
  • 915M mode: install two 915M antennas
  • 2.4G mode: install two 2.4G antennas
• Dual-band mode: install the 915M antenna on ANT1 and the 2.4G antenna on ANT2.

What’s Included

• 1 x GEPRC ELRS 915M/2.4G C3 Gemini Xrossband Receiver
• 2 x 915M/2.4G Dual-band T-Antennas (ipex1 80mm)
• 1 x Receiver silicone cable (SH1.0 4pin 100mm)
• 1 x Heat shrink tube
• 1 x User manual

Applications

• FPV drones requiring ExpressLRS 915MHz / 2.4GHz control link options
• Close-range racing and long-range flights requiring enhanced anti-interference performance (dual-band mode requires GemX TX / GeminiX TX)
• Projects needing bidirectional MAVLink (v2) for 2-in-1 remote control and data transmission

Details

The GEPRC ELRS C3 Gemini Xrossband receiver pairs 915M and 2.4G dual-band support with dual antennas and an integrated TCXO.

The receiver uses a Semtech LR1121 RF chip solution that supports 150–960MHz (sub-GHz) and 2.4GHz dual-band communication.

The C3 Gemini Xrossband receiver supports 915MHz Gemini, 2.4GHz Gemini, and dual-band communication modes for flexible ELRS setups.

The 915MHz + 2.4GHz dual-band T-antenna setup pairs with the C3 Gemini receiver board labeled ANT1 and ANT2 for streamlined installation.

Single-band setups use two matching antennas for 915M or 2.4G mode, while dual-band uses 915M on ANT1 and 2.4G on ANT2.

The built-in TCXO helps keep frequency stability for the receiver across changing temperatures.

Bidirectional MAVLink (v2) support enables two-way remote control and data transmission between the radio controller, drone, GCS, and AAT.

The C3 Gemini receiver supports an RX_AS_TX firmware option for 100mW output when used with a custom JR bay modification kit.

The GEPRC C3 Gemini Xrossband receiver includes an RGB status LED, Wi‑Fi firmware upgrade support, and an SH1.0 connector for straightforward wiring.

The receiver connects to the flight controller with four wires—GND, 5V, TX, and RX—and the Betaflight connector pin order should be verified before plugging in.

The frequency compatibility chart shows the 915M/2.4G C3 GemX RX supports 915MHz, 2.4GHz, and Gemini Xrossband operation.

The GEPRC ELRS C3 Gemini Xrossband receiver measures 18×23.6×5.7mm, weighs 1.6g, runs on 5V, and uses an IPEX1 antenna connector.

Dual ANT1/ANT2 antenna connectors and clearly labeled G/5V/T/R pads make wiring the C3 GemX ELRS receiver straightforward in a build.

The GEPRC ELRS C3 GemX receiver uses dual ANT1/ANT2 antenna connectors plus clearly labeled G/5V/T/R pads for straightforward wiring.

The GEPRC C3 Gemini Xrossband receiver includes two ANT1/ANT2 coax leads with cross-style antennas for flexible mounting on your build.

The GEPRC ELRS C3 Gemini Xrossband receiver kit includes two 915M/2.4G dual-band T-antennas, a 4-pin SH1.0 silicone cable, and a heat-shrink tube for a tidy install.