RadioMaster XR4 Receiver – dual-band ExpressLRS Gemini Xrossband control link

RadioMaster XR4 Receiver is a compact ExpressLRS receiver that combines two independent RF circuits, support for the 2.4 GHz and 868/915 MHz frequency bands, and Gemini Xrossband, or Gem-X, technology. It is suitable for FPV drones and other RC models with compatible control electronics where a stable, low-latency control link is essential.

RadioMaster XR4 Gemini Xrossband Dual-Band ExpressLRS Receiver allows you to configure the radio link to suit your transmitter and preferred operating mode. Its lightweight design makes it a practical choice for both new drone builds and upgrades to existing ExpressLRS systems.

Gemini Xrossband – simultaneous communication across two frequency bands

Gemini Xrossband enables control data to be transmitted simultaneously in the 2.4 GHz and sub-1 GHz frequency bands. In this mode, one RF circuit operates in the 868/915 MHz band and the other in the 2.4 GHz band. The exact frequency range depends on the regional configuration.

Using two frequency bands simultaneously increases the likelihood of a control packet reaching the receiver even when interference affects one band. This helps maintain more consistent link quality during freestyle flying or in environments with many nearby radio devices.

To use Gem-X mode, your transmitter or transmitter module must also support Gemini Xrossband. Replacing the receiver alone does not add dual-band transmission to an existing single-band transmitter.

Two independent RF circuits and True Diversity

RadioMaster XR4 Receiver uses two Semtech LR1121 RF transceivers and an ESP32D4 microcontroller. Its True Diversity design enables signal reception through two independent receiving circuits.

In addition to Gem-X, XR4 supports single-band Gemini mode and standard ExpressLRS operation. In single-band Gemini mode, the same control packet is transmitted simultaneously on two different frequencies within one band. Gem-X uses two separate frequency bands for this purpose.

The main benefit of Gemini is more reliable control packet reception and more stable link quality. This does not automatically increase maximum flight range: antenna placement, environmental conditions and the selected RF mode still affect link performance.

Lightweight and compact design

RadioMaster XR4 Receiver measures 22 × 18 × 4 mm and weighs just 1.7 g without antennas. The package includes two dual-band T-antennas that connect to IPEX-1 connectors.

The small circuit board leaves more room for other drone components. When installing it, allow space for the antennas and wiring so they can be secured firmly and kept clear of moving parts. Careful placement is particularly important in a compact FPV frame where electronic components sit close together.

CRSF interface and supply voltage

The receiver operates on 4.5–8.4 V DC and connects to a flight controller via a CRSF interface. A secondary UART port is available for advanced functionality. Solder pads along the edges of the circuit board make wiring easier.

Before installation, check the flight controller’s power output and wiring diagram. The correct supply voltage and a properly configured serial port help ensure reliable communication between the receiver and flight controller.

Configuration and firmware updates via Wi-Fi

Built-in Wi-Fi provides access to a web-based configuration interface from a computer or mobile device and allows receiver firmware updates. The firmware target is RadioMaster XR4 2.4/900 Gemini RX.

Before use, check that the transmitter and receiver have compatible ExpressLRS versions, frequency settings and operating modes. This allows you to configure the link for your existing equipment and use its supported features.

Package contents

The package includes one RadioMaster XR4 Receiver, two dual-band T-antennas, one CRSF connection cable, three pieces of heat-shrink tubing and a manual card.

RadioMaster XR4 Receiver is suitable for users looking for a lightweight ExpressLRS receiver with flexible connectivity and the option to use Gemini Xrossband with a compatible transmitter.

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