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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: Turnigy 9X Version 2 (Part 3)

A CLOSER LOOK

Old receiver versus new receiver

Dated: 22 June 2010

The Receiver

The old (version 1) FlySky receiver on the left (above) was rebranded "Hobby King" and came with a small satellite to provide diversity -- that was quite amazing for such a low-priced system.

The new 8-channel receiver (on the right, above) is cheaper than the old one, a cost-reduction probably made possible by the fact that there's no longer a satellite.

The big question on my mind was "how can they mitigate the effects of multi-pathing and shadowing without a satellite?" When I tried to use the version 1 receiver without a satellite it worked but gave nasty lockouts at comparatively close range I sure hope the version 2 is better.

FlySky have taken a two-fold approach to this. Firstly they've changed from using a simple quarter-wave wire antenna to using a sleeved dipole (something Hitec euphemistically call a BODA). This antenna provides a little more sensitivity than the old wire antenna so should help somewhat.

However, the biggest mitigation for the rather peculiar things that happen at 2.4GHz is the switch to a frequency-hopping system rather than the single-frequency DSSS method used before.

The use of a sleeved dipole and frequency hopping has worked surprisingly well for Hitec with its Optima 6 and Optima 7 receivers, both proving more than capable of delivering almost bullet-proof performance even in very large models. Perhaps the new Turnigy/FlySky system will do the same -- I won't know until I've done the flight tests. Unfortunately, because it's winter here and I may not get to flight test the system for weeks (depending on how the weather works out), I've opted to publish this review without the flight tests and then update it later.

inside the 9X receiver

The physical design and construction of the 8-channel receiver is now vastly improved over the earlier version. Gone are the awkwardly placed capacitors that look like after-thoughts and all the electronics are now nicely contained on a single spacious circuit board. The electrical design is changed only slightly and the same Taiwanese 2.4GHz transceiver chip is used as before. Although this isn't the most sensitive chip on the market and it has no pre-amplifier to boost its capabilities, it should (at least in theory) do the job.

Turnigy 9X receiver antenna

I was a little concerned to see that the receiver's circuit board was hot-glued into the plastic case and that after removing the hot-glue so I could get a better look, it tended to move around when servos and battery leads were plugged in and out. I also noticed the use of a largish crystal rather than a tiny surface-mount (SMT) version. Crystals this size tend to be far more fragile than their SMT equivalents. This receiver could be a little more fragile than most 2.4GHz units if you have a crash or high vibration levels. But remember (yes that's right), it's only a $60 radio!

The bind LED is hidden away inside the radio such that it is obscured by the label on the top surface. To see if the LED is illuminated you must look through the side of the smoked plastic case.

Binding itself is a painless operation and simply involves inserting the bind-plug into the marked servo-slot, holding down the bind button on the transmitter while turning it on and then powering up the receiver. Although the transmitter bind-button is also labeled "range test" I have not had time to verify that this function is supported -- it certainly wasn't on the old system.

Unfortunately, the receiver has no failsafe so, regardless of whether it has good range and even if the loss of the satellite doesn't compromise its ability to cope with shadowing and multi-pathing, this is a system for *small* models only. You would not put this receiver into a large glow or gas-powered model, nor would you use it in a jet. But who am I kidding -- a $9 receiver in a jet??

And, just in case you're wondering, the version 2. receivers do not bind to the version 1 transmitter modules. Sorry, but if you want more receivers for your old HK/iMax/FlySky/Eurgle 9X radio then you'd better snap them up while they're still available -- there's no backwards compatibility here I'm afraid.

On to Page 4 Back to Page 2

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The Blog

Updated: 20 Sep 2012
Here's a blog that will keep you informed just what's going on behind the scenes at RC Model Reviews and also tells you a little more about myself.

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Since this has become a very frequently asked question, I've posted this simple guide to getting your product, or a product you're thinking of buying reviewed here at RCModelReviews

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