BrotherHobby C3 900/2400 Dual Band 100mW Gemini RX ExpressLRS Receiver (915MHz/2.4GHz, IPEX1)

Overview

BrotherHobby C3 900/2400 Dual Band 100mW Gemini RX is an ExpressLRS receiver supporting 915MHz and 2.4GHz operation, designed around dual Semtech LR1121 RF chips, an ESP32-C3 main control chip, and a built-in TCXO for stable frequency performance.

Key Features

• Dual-band operation: 915MHz and 2.4GHz (supports sub-GHz and 2.4GHz LoRa)
• Dual 100mW telemetry power (2 x 100mW)
• Built-in TCXO (temperature compensated crystal oscillator)
• Designed to receive signals from all directions
• Dual-band antenna design for 915MHz + 2.4GHz (no need to replace antenna when switching frequency band)
• Onboard features/labels: BOOT, RGB indicator light, IPEX1 socket, lock socket, and pads marked GND / 5V / TX / RX

Specifications

Wiring & Configuration (Betaflight Example)

• Wire the receiver to the flight controller: GND to GND, 5V to 5V, TX to FC RX, RX to FC TX.
• Enable the corresponding UART (example shown: UART2) as Serial RX in Betaflight Configurator under the Ports tab.
• In the Configuration tab, set Receiver Mode to Serial-based receiver and select CRSF as the protocol.
• Telemetry is optional and may reduce stick update rate due to transmit slots being used for telemetry.

Binding

• Power on the receiver three times in a row to enter frequency matching mode (indicator light flashes twice).
• On the radio, open the ExpressLRS LUA interface and select [BIND] to confirm.
• Indicator light stays on constantly when frequency matching is successful.

Indicator Light Meanings

• Rainbow color gradient: power on self test
• Green and orange lights flash alternately: enter WiFi upgrade mode
• Red light flashing fast: no RF chip detected
• Orange dual flash: Crossover Mode
• Orange triple flash: connected, but does not match the settings in model match
• Orange slow flash: waiting for connection
• Always on: connected

What’s Included

• BrotherHobby C3 900/2400 Dual Band 100mW Gemini RX receiver
• User manual
• 4*30awg connection line*1
• T-Shape Dual Band Antenna*2
• Transparent Heat Shrinkable Tubing*2

For installation or compatibility questions, contact support at support@rcdrone.top or visit https://rcdrone.top/.

Details

BrotherHobby C3 900/2400 dual-band Gemini RX receiver uses a compact board layout with a plug connector and clearly labeled pads for clean wiring.

Dual Semtech LR1121 RF chips provide sub‑GHz and 2.4GHz LoRa support with dual 100mW telemetry power.

Dual-band Gemini communication uses both 915MHz and 2.4GHz links between the transmitter and receiver for better interference resistance.

A built-in TCXO temperature-compensated crystal oscillator helps keep the receiver’s frequency stable across temperature changes.

BrotherHobby Gemini RX ExpressLRS receiver uses an ESP32-C3 main control chip and provides GND, 5V, TX, and RX solder pads plus an IPEX1 antenna connector.

The 915MHz and 2.4GHz dual-band antenna supports switching between bands without swapping antennas.

The BrotherHobby C3 900/2400 Gemini RX supports 915MHz and 2.4GHz with an IPEX1 connector, 3.6–5.5V input, and labeled GND/5V/TX/RX pads for straightforward wiring.

Serial ExpressLRS receiver setup uses four wires (GND, 5V, TX, RX) to the flight controller and requires enabling a UART Serial RX with CRSF selected in Betaflight.

The ExpressLRS receiver bind guide explains the three-power-cycle frequency match procedure and the indicator LED color meanings for connection and mode status.

BrotherHobby C3 900/2400 Gemini RX comes with the receiver board, user manual, a 4×30AWG connection lead, two T-shape antennas, and heat-shrink tubing.