In previous articles, we have discussed the FrSky R9M system along with the R9M Lite as well, two Long-Range systems created by FrSky to overcome the drawbacks of 2.4GHz systems such as the lack of penetration around obstacles and lower range compared to 900MHz systems. In this article, we will check out the FrSky R9 Slim+ Long Range Receiver for the R9M RC link system and see whether it is apt for usage on your drones and other builds.

Why the R9 Slim+?

The FrSky R9 Slim+ has been created by FrSky to compete against the Team Black Sheep Crossfire Mini receiver. Since the full-size FrSky R9 receiver is too big for mini quads, the R9 Slim. You can get R9 Slim from HorusRC


Features of FrSky R9 Slim+

  • 915MHz (Non-EU Version)/ 868MHz(EU Version)
  • Optimized performance
  • Detachable IPEX antennas x 2
  • Small and easy to set up
  • Low latency and high precision
  • Redundancy is supported
  • Full range telemetry with Smart Port functionality
  • Battery voltage detection
  • Analog or digital RSSI output via pin or channel
  • Supports inverted S.BUS & S.Port (FrSky already inverts its signals, so this is basically the uninverted signals) which makes it compatible with F1, F3 & F4 Flight controllers.
  • PCB protection with the conformal coating craftwork


The FrSky R9 Slim+ comes with antenna diversity, meaning that it has two antennas for reception. This improves the range compared to a single antenna setup. The antenna connectors are IPEX style detachable antennas, thus making it easier for swapping the antennas out in case you damage them.

Another noteworthy feature of the R9 Slim+ is its ability to output inverted S.BUS & S.PORT signals. FrSky by default output inverted signal on both S.BUS & S.PORT which is why we need inverters on our Flight Controllers with F1/F3/F4 processors to decode the inverted signals. But with the R9 Slim+, FrSky was generous enough to include inverted signals ( two times inverted so technically the actual uninverted signal!) for the S.BUS and S.PORT signals.

This way, all your Flight Controllers, regardless of being incompatible with inverted signals, will work fine with this receiver; even the S.PORT works, getting you full-range telemetry!


Specifications of R9 Slim+

  • Dimension: 32*13.5*5mm
  • Total Weight: 4.3g (with antennas)
  • Number of Channels:
    Non-EU Version: 6/16CH (Telemetry)
    EU Version: 6/8CH (Telemetry) / 6/16CH (Telemetry) / 6/16CH (No Telemetry)
  • With RSSI Output: Analog 0~3.3V
  • Operating Voltage Range: DC 3.5V~12.6V(3s Li-Battery)
  • Operating Current: 100mA@5V
  • Operating Range: Up to 10km or above
  • Firmware Upgradable
  • Compatibility: R9M and R9M Lite


FormFactor & Pinouts 

The R9 Slim+  has a long design with narrow height and thus makes it suitable for mini quads.

Since the receiver also features 6 PWM channels as well, it makes it easy to use with planes and fixed wings or even an RC car if you want to do long-range with that. I mean, who wouldn’t want to drive your car for miles with FPV? FPV makes everything so much more fun ;)

The top part of the receiver houses the BIND button that is used to bind the receiver with the transmitter of your choice; any FrSky Taranis radio with the R9M or R9M Lite ( or Pro) transmitter module will work with this receiver.


You also find two LEDs beside the BIND button to show the status of the receiver. One Green  & one Red LED. The antenna connectors are on the right side of the receiver.

One the left side is where you find the connector 1. This connector has outputs and inputs as follows:



-S.BUS IN (for redundancy)

-S.BUS OUT (to flight controller)

-RSSI OUT (0 to 3.3V analogue out)





The bottom side is plain except for the second connector. This connector has pinouts as follows:










As far as the receiver pinout and form factors are considered, these are the only points to note.

The newer FrSky R9 Slim+  has OTA support via the new FrSky ACCESS Protocol which also provides more features as well.

In this article, we have seen about the FrSky R9 Slim+  receiver, its usage, pinouts and other factors and how it works with the R9M system of transmitter modules.