Quick Answer
The RFDesign TXMOD is a JR-module that drops into the back of compatible RC transmitters and adds long-range RC control over the 868MHz or 900MHz band. It works by converting your transmitter's PPM output into a signal sent through an RFDesign telemetry modem, giving you far more range than standard 2.4GHz ELRS or Crossfire links. It is designed for fixed-wing mapping, survey, and inspection drones where reliable control at distance matters.
What Is the TXMOD?
The TXMOD is a small module made by RFDesign that plugs into the JR-module bay found on many popular RC transmitters. Radios like the FrSky Taranis X9D, FrSky Horus, and RadioMaster TX165 all have this expansion slot. Once installed, the TXMOD reads your stick inputs as PPM or SBUS signals and forwards them over a long-range 868/900MHz link to your drone.
Unlike 2.4GHz RC links such as ELRS or Crossfire, which are great for freestyle and racing FPV, the TXMOD operates on a lower frequency with better range through obstacles and over longer distances. This makes it suited to survey drones, mapping aircraft, and inspection platforms that need to fly miles from the pilot.
The TXMOD also carries MAVLink telemetry back from the aircraft. A built-in 2.4GHz WiFi link lets you connect a phone, tablet, or laptop running Mission Planner or QGroundControl to view live telemetry without a separate ground station radio.
How Does It Work?
The TXMOD does not replace your transmitter. It sits in the JR-module bay and acts as a bridge between your radio and the aircraft. Here is the signal path:
- Your transmitter sends PPM or SBUS signals into the TXMOD
- The TXMOD passes RC data to a paired RFDesign ground modem (RFD868x, RFD868ux, RFD900x, or RFD900ux)
- The ground modem transmits over 868MHz or 900MHz to a matching air modem on the drone
- The air modem feeds RC channel data into the flight controller
- Telemetry flows back the same path to the TXMOD's WiFi for your ground control station
This means you need two modems for a working system: one on the ground (paired with the TXMOD) and one on the aircraft. Bundles are available that include both the standalone TXMOD module and a matching ground modem.
Compatible Transmitters
Any transmitter with a JR-module bay can accept the TXMOD. Known compatible radios include:
| Brand | Models |
|---|---|
| FrSky | Taranis X9D, X9D Plus, Horus series |
| RadioMaster | TX15, TX16S, and other JR-bay models |
| JR | Most JR transmitters with module bay |
| TBS | Mambo (with adapter) |
If your radio has a JR-module slot, the TXMOD will physically fit. The module accepts a wide 5-18V input supply, so it draws power directly from the transmitter bay.
TXMOD vs 2.4GHz ELRS/Crossfire
These are different tools for different jobs. ELRS and Crossfire run on 2.4GHz and are ideal for FPV freestyle, racing, and general sport flying where range is measured in hundreds of metres to a few kilometres. The TXMOD uses 868/900MHz, which propagates better over distance and through obstacles, making it better suited to professional and commercial operations flying many kilometres from the pilot.
The trade-off is latency. The TXMOD path goes through a modem pair with MAVLink encoding, which adds latency compared to the direct link of ELRS. For survey and mapping work that does not require real-time stick response, this is acceptable. For acrobatic freestyle, it is not.
For a deeper look at choosing between RFDesign modems, see our RFDesign module comparison guide.
What to Buy
You need the TXMOD module and at least one matching ground modem to get started. Bundles save time by including both:
- RFD 868 TXMOD — standalone module (pair with your own modem)
- RFD 868 TXMOD Bundle V2 — TXMOD paired with an RFD868x ground modem
- RFD868ux TXMOD V2 Bundle — TXMOD paired with the smaller RFD868ux modem
All RFDesign modems and accessories are available in our RFdesign collection. For the full picture of building a long-range data link, read our guide on building a complete long-range drone data link.
FAQ
Q: Does the TXMOD replace my RFD telemetry modem?
A: No. The TXMOD works alongside an RFDesign modem (X or UX series). A bundle includes both the TXMOD and a ground modem, and you still need an air modem on the aircraft.
Q: Will the TXMOD work with ELRS or Crossfire receivers?
A: No. The TXMOD is a separate RC link. It connects to the flight controller via the paired modem, not through a receiver. You would not run ELRS and TXMOD on the same aircraft.
Q: Do I need a licence to use the 868MHz TXMOD in the UK?
A: The 868MHz band is licence-exempt in the UK under OFCOM regulations, but you must stay within the permitted power limits. The RFD868 TXMOD operates within these limits. The 900MHz variant is for use in the Americas and other regions, not the UK.