Radiomaster RP4TD ExpressLRS 2.4GHz Diversity Receiver

1. Introduction

The Radiomaster RP4TD is an advanced ExpressLRS 2.4GHz Diversity Receiver designed for high-performance drone and fixed-wing applications. Featuring dual SX1281 RF processors, dual TCXO oscillators, and an upgraded rigid dual-antenna system, it offers enhanced signal stability, range, and accuracy. This manual provides essential information for the proper installation, configuration, and operation of your RP4TD receiver.

Image: Radiomaster RP4TD ExpressLRS 2.4GHz Diversity Receiver with included accessories.

2. Safety Information

⚠️ Disclaimer: For recreation use only. Illegal modification of drones/planes is prohibited. Please also pay attention to the relevant laws and regulations on the use of drones/planes in your country/area to ensure legal use.

Always ensure proper wiring and insulation to prevent short circuits. Operate your RC equipment responsibly and within legal limits.

3. Package Contents

Verify that all items are present in your package:

• 1 x RP4TD ExpressLRS 2.4GHz Diversity Receiver
• 1 x CRSF wire
• 3 x Heat-Shrinkable Tube
• 2 x 65mm 2.4GHz T Antenna (Pre-installed on receiver)
• 1 x User Manual (this document)

Image: Contents of the RP4TD receiver package.

4. Specifications

Receiver Dimensions

Antenna Dimensions

Receiver Weight (1.4g without antenna)

5. Setup and Installation

5.1 Physical Installation

The RP4TD receiver is compact and lightweight, making it suitable for various models. Ensure it is mounted securely in your drone or fixed-wing aircraft, away from high-current wires or other potential sources of interference. The antennas should be positioned to provide optimal signal reception, ideally at a 90-degree angle to each other for diversity.

Image: Top view of the RP4TD receiver board, showing U.FL antenna connectors and pads.

5.2 Wiring

Connect the receiver to your flight controller using the provided CRSF wire. The RP4TD uses a CRSF bus interface and requires a UART connection on your flight controller. The pads are labeled RX, TX, 5V, and G (Ground).

Image: Diagram showing receiver pinout (RX, TX, 5V, G) and Betaflight configuration steps.

5.3 Betaflight Configuration

After physical installation and wiring, configure your flight controller using Betaflight Configurator:

1. Open Betaflight Configurator on your computer.
2. Navigate to the Ports tab.
3. Enable the corresponding UART (e.g., UART2) that your receiver is connected to as a Serial RX.
4. Click Save and Restart.
5. Go to the Configuration tab.
6. In the Receiver panel, select Serial-based receiver.
7. For the Serial Receiver Provider, choose CRSF.
8. Click Save and Restart again.

6. Operation

6.1 Traditional Binding Procedure

To bind your RP4TD receiver to your ExpressLRS compatible transmitter:

1. Ensure your transmitter/radio is powered OFF.
2. Plug in and unplug your receiver to power it ON and OFF three times consecutively.
3. Observe the receiver's LED. It should begin a quick double blink, indicating it is in bind mode.
4. Power ON your transmitter/radio.
5. Access the ExpressLRS Lua script on your transmitter.
6. Navigate to the [BIND] button within the Lua script and activate it to send out a binding pulse.
7. If the binding is successful, the receiver's LED will show a solid light.

Note: For advanced binding methods, such as using a Binding Phrase, ensure the Binding Phrase field is uncommented in the Device options on the receiver.

7. Maintenance

The Radiomaster RP4TD receiver is designed for durability. To ensure its longevity and optimal performance:

• Keep the receiver clean and free from dust, dirt, and moisture.
• Avoid exposing the receiver to extreme temperatures or direct sunlight for prolonged periods.
• Regularly inspect antenna connections for any signs of damage or loose connections.
• Ensure proper airflow around the receiver to aid in heat dissipation, especially during intensive use.

Image: Key features of the RP4TD receiver, including fast heat dissipation.

8. Troubleshooting

• No Power/LED Off: Check wiring for correct polarity and secure connections to the flight controller's 5V and Ground pads. Ensure the flight controller is powered.
• Receiver Not Binding:
  • Verify the binding procedure steps are followed precisely (3 power cycles for bind mode).
  • Ensure your transmitter's ExpressLRS module is powered on and the Lua script is correctly sending a bind pulse.
  • Check that the firmware versions on both the receiver and transmitter are compatible (ExpressLRS V3.3.0 pre-installed on receiver).
  • Confirm the Binding Phrase (if used) is identical on both devices.
• No Signal/Intermittent Signal:
  • Inspect antenna connections for damage or looseness.
  • Ensure antennas are positioned correctly and not obstructed by carbon fiber or other conductive materials.
  • Check for sources of RF interference near the receiver (e.g., VTX, ESCs).
  • Verify the correct UART is selected and configured as Serial RX in Betaflight.
• Incorrect Telemetry Data: Ensure the UART connection for telemetry (TX pad) is correctly wired and configured in Betaflight.

9. User Tips

• Thorough Testing: After installation and binding, always perform thorough ground testing of all controls and telemetry before your first flight.
• Firmware Updates: While the receiver comes pre-installed with ExpressLRS V3.3.0, regularly check the official ExpressLRS website for newer firmware versions and update if necessary for improved performance or new features.
• Antenna Placement: Experiment with antenna placement to find the optimal configuration for your specific aircraft, maximizing signal range and reliability.

10. Warranty and Support

For detailed warranty information and technical support, please refer to the official Radiomaster website or contact your retailer.

Additional resources and the latest firmware information for ExpressLRS can be found at the official ExpressLRS website: https://www.expresslrs.org/2.0/

A digital copy of this user manual is available in PDF format: View User Manual (PDF)

11. Regulatory Information

FCC ID: 2BBP3-RP4TD

This device complies with Part 15 of the FCC Rules. Operation is subject to the following two conditions: (1) this device may not cause harmful interference, and (2) this device must accept any interference received, including interference that may cause undesired operation.