FrSky X4R RSSI Mod

Rusty Sun, 01/08/2017 - 23:47

FrSky X4R RSSI Mod

FrSky X4R, X4R-SB RSSI Pad location

It may not be well known, even though the owner's manual shows it, but the X4R is capable of outputting a RSSI signal for either a flight controller or an OSD. This is in addition to having the RSSI telemetry already sent back to your FrSky transmitter. The RSSI pad makes it pretty easy for anyone with moderate soldering experience to access this port and have it brought out to the connector of your choice. Most people I know wire up a servo style plug.


What is needed to do this Mod?

Only a few things are needed to do this mod:

  • Soldering tools: soldering Iron, solder, flux (optional) 
  • Some wire, a piece of servo cable works well for this.
  • Wire cutters/strippers
  • Connector of your choice, and crimper for the terminals (small pliers can be substituted in a pinch)
  • Hot glue (optional, to secure the wires)

Making the modification

Performing this mod is really easy.

  1. Begin by cutting a length of servo cable to the length needed. The wire needs to be as long as needed to connect to your OSD or flight controller, basically how far away your receiver is from what you want to connect it to, plus about 2-3 inches.
  2. Once cut, split out the 3 wires and discard the center, or red power wire. In this case we only need signal and ground, and in some cases ground may be optional.
  3. Remove the cover from the X4R receiver. To do this, slide the small plastic wrap off the cover and unfold the cover. There may be a little bit of double sided tape holding the cover on, gently pull it off.
  4. Locate the RSSI pad. It is located right next to one of the antenna connectors.
  5. Solder the signal wire to this pad. a little solder flux can be used, but if your solder already has a flux core, it is not really needed.
  6. Solder the ground wire to one of the 90° header pins that corresponds to ground. (use the picture for reference)
  7. Once you have the two wires soldered, carefullt ropute the wires to avoid shorts and use a little hot glue to secure the wires so they don't get pulled off.
  8. Add your requred connector to the other end, and that is it. You now have FrSky RSSI signal brought out to be used by your device of choice.

RSSI Pad Location






Here is the video to the MOD