Review: FlySky, Turnigy, iMax 9X 2.4GHz radio control set

Your Reviewer

My Credentials
So who's doing this reviewing then?

Well I've been building and flying or driving radio controlled models for over 40 years and during that time I like to think I've built up a reasonable amount of knowledge.

I'm also a qualified electronics engineer who has worked in radio frequency, analog, digital systems and software for more than three decades. In fact I designed and built my first RC set back in 1969.

For the past nine years I've also been involved in the design and manufacture of some rather sophisticated engine technology and UAV flight control systems.

So, chances are I've been there, done that and have a huge pile of tee shirts to prove it.

Right now I'm heavily into 3D flying and enjoy all aspects of the RC hobby. I may be old but I don't feel it.

In the Pipeline

Here's just a little bit of what's to come on this site...

RC explained: Demystifying terms such as PCM, PPM dual conversion, single conversion, full-range etc., this feature will explain it all.

Cheap Chinese Engines: Just how good are those cheap Chinese glow and gas engines that sell for half the price of their "brand-name" equivalent? I put several to the test.

Build your own radio gear?: Back in the old days, building your own RC gear was not uncommon and now the arrival of 2.4GHz has made it practical again.

Review: FlySky/Turnigy/iMax 9x 2.4GHz RC system

THE TECHNICAL STUFF

Documentation

Although well illustrated and laid out, the first edition manual I received was the worst piece of Chinglish I've seen in many years.

Here's an extract from the original first-edition manual (the mistakes are not mine):

"P. MIX2 (PROGRMA MIXING2)
Mix purpose to accuse of form to get rid of little mistake of organism, make it is it can take the heart conveniently even more to have not to handle. The very wanton one mixes accusing of among the channel"

Can you make sense of that?

Fortunately for some, the software is "inspired by" the JR 9X/9303 which is one of the easier to program Asian-made radios so you probably won't need to refer to the manual very often.

With support for five-point throttle and pitch curves, four CCPM swashplate modes, up to seven programmable mixes, flight modes, servo delay, and all the other usual programmable functions of a hi-end radio it's just as well programming is so easy or the manual would drive you mad.

The illustrations showing how to bind (they call it "pairing" the receivers was a little too small and indistinct for my old eyes but it's a simple task once you work out what you're supposed to do.

Unfortunately, no advice is given as to how the receivers should be installed which is a shame because the performance of all 2.4GHz systems is highly dependent on a good installation and this is not necessarily intuitive.

The technical stuff

Very little technical documentation or specification is provided with the iMax 9X.

Based on my own tests and observations, the system appears to be a non frequency-agile DSSS system, not dissimilar to the Assan system, another 2.4GHz product out of China, although Assan have upgraded their system to use two separate parts of the band now.

Being non-agile means the iMax 9X is not as well suited to extremely harsh RF environments as either the Futaba FASST or Spektrum/JR 2.4GHz systems but given the price differential this system definitely has a place in the market.

Despite being sold as a transmitter/receiver pair, the system is actually module-based so it is necessary to set the transmitter to PPM mode when using it on 2.4GHz. Unfortunately this means there is no failsafe capability -- a big minus point for some types of models such as large or fast craft that could cause danger to human life if they were to get hit by interference.

Switching to PPM mode also reduces the number of channels from nine to just eight so perhaps they ought to call this the 8X 2.4GHz system. Having said this -- the Futaba 9C suffers the same limitation, only offering 9 channels in PCM mode.

And speaking of PCM... an FM transmitter module and PCM receiver is also available for the iMax system, effectively making it a traditional narrow-band system.

This helps explain why, despite being sold as a 2.4GHz system, the transmitter also has a conventional telescoping antenna fitted.

Page 3 (The Receivers)