FrSky RB20. In this review we will be checking the FrSky RB20, which is a switchboard module capable of operating 2 long range receivers and 2 batteries in the same aircraft, so that you can fly more confident of knowing that your aircraft isn't going to fail.

The FrSky RB20 module can handle high operating currents and it supports high-current servos, not as the previous models which didn’t support these features. This board is also capable of automatically switching telemetry amongst RX1 and RX2, this is one of the main reasons why you can trust on this board to keep your aircraft safe, because if a receiver fails, at least with the redundancy function you can still trust in the other receiver also built in your aircraft.


Like already mentioned, with this product it is also possible to run servos directly from the switchboard as it has complete protection from high voltage overload. With the FrSky RB20 you will also be able send information from the aircraft back to the radio, information such as voltage and overload indication, all thanks to Smart Port which broadcast the provided telemetry back to your FrSky transmitters.


The FrSky RB20 has a multi-channel output, this means that the device can output many channels, more specifically, it can run up to 15 servos. As I mentioned before, it can also run high operating currents, much more than the previous versions, making it possible to run high-current servos. About the telemetry, it is selected automatically between the RX1 and RX2 output although can decide on or off from telemetry with RX1 S.P and RX2 S.P

It is important to bear in mind that the high voltage servo output is supported on every channel, as every channel counts with overload protection. Another cool feature about the FrSky RB20, is that it is compatible with other FrSky S.Port products, and as is it supports dual receiver of the same or from different series, the power of the unit will be dual.


Some more technical details about the FrSky RB20 are that the integrated S.Port telemetry can be used to give feedback about voltage, current, capacity, overload indication, etc. And the settable servo signal output period is of 50Hz of servo outputs, that is 20ms a period, or even equal to the input of SBUS cycle.

When you are going to install it, it is also important to connect it to the recommended input voltage range which goes from DC 4 up to 8.4 volts, but also from 1 up to 2s Lipo battery or 4 up to 6s with a NiMH battery. The operating temperature range of the RB20 is very diverse, working on extreme conditions of -20℃ but also up to 75℃. And it weights 37g and it has a dimension of 77×43×22mm.

Setting for Servo Signal Output Period

The period of the signal output in the FrSky RB20 is by default set to 20ms, it can also be set in order to be synchronized with the receiver, but it is not recommended to set analog servos to the receiver synchronized. Now, if you do need to set the signal output period you can follow these next steps.

To set the period of the signal output in the FrSky RB20 start by joining the signal output pins of channel 1 and channel 2 with a jumper. Then, connect the power supply to BATT 1 or BATT 2 outputs to power the unit. Now, if the green LED flashes quickly, that means that the signal output period has been synchronized with the signal output period of the receiver. Finally, you can disconnect both, the jumper from channel 1 with channel 2 and disconnect also the pins connected with the battery.

You may also find useful a small guide of the FrSky RB20 on how to distinguish between 20ms and the receiver synchronized, in order to know this, it is very simple, first, connect one receiver to RX1 IN or RX2 IN outputs pin, then, connect a power supply to the BATT1 or BATT2 pad. Now, with the device turned on, if the green LED is flashing quickly, this means that the receiver is synchronized to the output, but if instead, the green LED is turned on solid color, that means that it is set to 20ms output.

And that is it. As you can see, this device is a very powerful tool, and it has many other functions such as overload protection, it can also have firmware updates through S.PORT, you can also change the SBUS signal from negative to positive for RX1 IN and RX2 IN, and it has MPX connectors for batteries or BEC connection etc.