RFD900, RFD900+ - New long range radio modem

Hi All,

I would like to introduce you to a new radio modem that we developed for very long range datalinks!


Some of the key features of the RFD900 are as follows:

  • Multi point and point to point link capability.
  • Long range >40km depending on antennas and GCS setup.
  • 2 x RP-SMA RF connectors, diversity switched.
  • 1 Watt (+30dBm) transmit power.
  • Transmit low pass filter.
  • > 20dB Low noise amplifier.
  • RX SAW filter.
  • Passive front end band pass filter.
  • Open source firmware / tools, field upgradeable, easy to configure.
  • Small (30 x 57 x 13 mm), light weight (14.5g).
  • Compatible with 3DR / Hope-RF radio modules.
  • License free use in Australia, Canada, USA, NZ.


These modems are designed to support long range applications, while being easy to use and affordable.  

These modems have been flying in various platforms and have demonstrated excellent performance in real applications. 

RFD900 modems are now available at: http://store.rfdesign.com.au

Support within APM planner and the radio configurator from Michael Oborne is already available.

It works seamlessly with APM planner, all radio Mavlink parameters are available.

Update, December 2014:  The RFD900+ with improved specifications is available now at:


Seppo Saario



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I can confirm that the RFD900 does *NOT* use a DNT900 of any sort, and has no relationship to that product at all.   The RFD900 is an all-new design.  

In my opinion, It's also way more awesome.     :-)

Hi Seppo, hi all,

yesterday, i received mine!! The construction quality is great!

i figured out how we connect them by following the diagramm. After my first inverted conection i just used my 3dr radio cable and everything worked great!!   

   But still i have some questions:

-Can i use The ground side RFD900 modem with my 3dr radios on the air side? (ofcourse using the same settings on both sides) except power?

- we use one monopole and one dipole antenna provided for each unit, or we use the two dipols for ground and monopols for air?

- if i have some spare cloverleaf,patch or yagi antennas, which is the best way to pair them??

- how can we use ground plane by relocating the monopols on a foamy?

- finaly, how much should we raise power on both sides, to achieve the nominal performance with the provded antennas & keep the temp low?

thanks you all,



Hi James,

Yes, the RFD900 and 3DR-900 radios are 100% compatible so you can use them as you described.

The antennas can be configured in any way, but the best way is to have either polarisation diversity (different orientation, rg. horiz/vertical), or spatial diversity (different location).

The way I usually set the antennas is with 2x dipoles on the ground, one vertical, one horizontal.  In the air for a smaller platform I would have one monopole vertical, and the other horizontal, in slightly different parts of the airframe to avoid shielding due to fuselage/wings etc.

If you have a yagi, you can use one on the ground say in a vertical polarisation, and an omnidirectional dipole, for close in coverage.  

A groundplane on a foamy can be made with aluminium foil, or copper tape stuck on the outside/inside of the fuselage.  The outer shield of the coax (outer of antenna connector) must be in contact with the groundplane.

The plane diameter should be greater than a quarter wavelength at 915MHz to get the best results.

The modems can be run at full power up to an ambient temperature of 85 degrees without any issues.

The last 3dB of gain on the power amplifier does take the most current, so, if you don't need full power, +27dBm (500mW) is quite comfortable and cool.  



Hi Seppo,

Thanks for the info!! since everything is compatible, i will try different combos and post results.  One thing i noticed with 3dr900 and RFD900 is that when telemetry cable touches  a servo cable it jitters a bit, also i needed a longer cable. I used many shielded cables but the best results was using a usb cable, it has 4 inner ones shielded. Now even with a full powerd RFD900 and my wires like spaggeti during tests, i am absolutely jitter free!! 

Just a quick heads up ! - we now have 2 different length RG316 coax extension cables in store which make airframe installations much easier.  APM1/2 serial telemetry cables are coming next week as well.

Things have been a little quiet on the development front for new features as it's getting close to the competition date for the UAV outback challenge !

Hello James,

Any news on the RCLink? Would it be technically possible to add PPM sum in/out on the RFD900 modems as they are?

Kind regards,


I'm hoping to have some news on RCLink soon. (which is never soon enough, I know. Sorry for the wait!)

As for doing PPM sum directly on the RFD900, it's physically possible with the stock hardware, but I don't know if the software support can be made to fit/play nicely/work reliably alongside the radio stuff.

What plane were you using? I am guessing it was a X8 or such? Time taken and what batteries did you use?


This is exactly what I've been looking for! A system were you can realtime-control your plane via telemetry. Unfortunately I'm living in Europe and don't think its safe to use the 900MHZ band. 

For how long time should the europeans wait for a similar system in 433MHZ or the 865MHZ-frequency? Is it possible to make it 1w-configuration?

Actually I'm building my X8 drone this winter, so it would be nice to know if should wait for this system, or just go for a regular, boring transmit-system...

Best regards Marius

Seems like the X8 became famous. I am also finishing up my X8.

As for the radios, these are 1W versions. RClink seems like to be just mounted in the RFD900 radios according to Seppo.

Thanks for the reply James.

Any update on the RCLink :) ?

Now that the 2012 outback challenge is over for this year - there is some more time to get RCLink developed.  Planning prototype release in a month or so and planning on having final versions available through early December :)

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