Introduction:

There are various suppliers and protocols out there, but recently FrSky (pronounced Free Sky) has been growing in popularity thanks to the good blend of features, reliability and price on offer. As flight controllers become more advanced and allow users to customize additional features such as flight modes, buzzers and lights, the basic 6 channel receiver isn’t going to cut it. If you want to do more of these things at once, then a good option is the X4R-SB from FrSky.

The FrSky X4R-SB receiver is a compact, full range, 16 channel SBUS (digital) receiver, with an additional 3 PWM channels. The receiver allows you to use 16 channels with only a single signal wire, which is fantastic for putting together a clean build. The receiver has a smart port and can provide telemetry back to your radio, which is handy for low voltage warning and battery consumption, as well as a number of other readings depending on your flight controller.

X4R SB recever FrSky

Receiver diversity is a great feature and means that you have a more reliable, stronger signal even while cornering at long range. It is important to note that the antennas should be installed at a 90 degree angle to one another and that the exposed tip of the antenna is the most important part. This should be kept as straight as possible to get the strongest signal. Most builders now make a lightweight support using a cable tie, which the antenna is then attached to using heatshrink. This keeps the antenna up and out of your props, but is still a flexible enough solution not to just snap in a crash.

Installation is simple, as like most receivers the X4R-SB is powered by a 5V supply. Binding the receiver to your transmitter is straightforward and just involves holding the pair button as you power on the receiver. A single signal wire to a suitable receiver channel on the flight controller is all that is needed before you can get started and make any changes needed to your flight controller’s software configuration.

We have been using the X4R-SB for a few months now after making the switch to FrSky from a Turnigy 9X transmitter with 8 channel receiver. The X4R-SB provides a reliably strong signal when flying in areas that the Turnigy system had lost signal, such as behind trees and at longer range. On top of this, the X4R-SB provides the backup of giving audio warnings when you have low signal strength.

PROS:


  • Reasonably priced
  • Compact
  • Lightweight
  • Detachable/replaceable antennas with IPEX connector
  • Diversity
  • Telemetry

CONS:


  • No CPPM output
  • SBUS is not compatible with some older flight controllers, such as the popular NAZE rev5 (rev6 is ok) without some work around

Verdict:

We think the FrSky X4R-SB is a great receiver. It is simple to install and configure in the flight controller and provides us with telemetry back from the drone. More importantly, the rock solid reliability of FrSky has given us complete confidence in our control signal. Though we will admit we haven’t flown anywhere near the claimed “>1.5km” range, it has never lost signal where our previous system did. The receiver is compact enough to fit in all but the smallest micro build and has been robust enough to survive numerous heavy crashes.

Overall we would recommend the FrSky X4R-SB!

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