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Saturday, March 26, 2011

Spektrum DX8 Review

UPDATE:  Also see: Half of DX8 users report "unresolved" problems

UPDATE:  Also see: Head to Head: Aurora 9 vs Spektrum DX8



UPDATE: March 27, 2011.  While conducting an Aurora 9 vs Spektrum comparison, the DX8 dropped a link and destroyed the Z-8 all time fav Pitts Special.  Level flight, left to right pass, 40% power cruise, aprox 100 feet away and 100 feet high, the beautiful little RWB starburst Pitts popped up then slow rolled over to the left, no control whatsoever as the Spektrum radio system nosed it straight down into the dirt.  Likely an airborne receiver reboot with too little altitude to affect a complete reboot.
This my third model crash under an eerily similar, uncontrolled flight profile.  I call it the "Spektrum rock'n roll over"  Interestingly, the first two were with OrangeRx brand DSM2-compatible receivers.   However, that model (crashed twice from Spektrum loss of control) was my 4S 850W+ F8F Bearcat, which was probably too susceptible to brown out.  After doing more research on the topic of Spektrum brownouts, I learned that only 3S and lower powered models may be used safely with Spektrum radio systems.  With 4S+, you MUST buy a dedicated third party BEC, as 4S+ ESCs without a dedicated switching BEC cannot be used with Spektrum radio systems.  I apologize for incorrectly attributing these crashes to OrangeRx, when in fact they were due to my lack of homework understanding the inherently unsafe design of all Spektrum radio systems when used with such a setup.

For now, my entire Spektrum fleet is grounded.  Since I don't want to lose too much flying until I can replace all of my Spektrum Rx equipped planes and helis, I will be installing a high quality switching BEC before another one of my Spektrum aircraft endangers itself, and others, by taking off.

The high cost of this faulty radio line continues to mount, even as I hurry to phase out all Spektrum equipment from my RC collection.  In fairness to Spektrum, they are clear in their AR9000 Rx literature that you may sacrifice control of your model due to a known design defect:
"QuickConnect™ With Brownout Detection
Your AR9000 features QuickConnect with Brownout Detection.
• Should an interruption of power occur (brownout), the system will reconnect immediately when power is restored (QuickConnect).
• The LED on the receiver will flash slowly indicating a power interruption (brownout) has occurred.
• Brownouts can be caused by an inadequate power supply (weak battery or regulator), a loose connector, a bad switch, an inadequate BEC when using an Electronic speed controller, etc.
• Brownouts occur when the receiver voltage drops below 3.5 volts thus interrupting control as the servos and receiver require a minimum of 3.5 volts to operate."
Personally, I would prefer no loss of control over a by-design, brief loss of control, even when using new and very expensive Spektrum Rxs.  Uhg. 

.....
UPDATE: March 18, 2011.  After doing some quick web research on the latest unsafe DX8 defect, four bad potentiometers inducing random control inputs, bad centering, and stepped travel on all four stick axes, I found that this problem is inherent to most if not all DX8 radios.  Loads of people are writing about this problem, and perhaps 50% noted that Spektrum service could not fix the issue, likely replacing defective parts with new defective parts.  Requests for a full refund of wasted money on these defective radios reportedly go  unanswered by an unresponsive manufacturer.   I myself have never been able to get a human on the phone, and not for lack of trying--my limit is 60 minutes on hold.  So....

Having decided to throw my DX8 radio away, since it is definitely unusable, probably unserviceable, and thoroughly unreliable--all making it morally unsalable--it seemed there was little to lose by trying a user-recommended fix that was heralded as working each time it was tried.  There is obviously a risk to servicing my own radio, but what is there to lose when the thing is garbage at this point?

The user-recommended fix is to properly lubricate and clean the pots by applying a drop or two of WD-40 to the visible metal pot bearings, then working it in with stick movement.  This fixed all four of my defunct pots, initial results show smooth operation of every stick function.  Since I couldn't find a good photo tutorial on how to do this, here is my own:

Applying WD-40 proved to be ineffective in the long term, though it did seem to help in the short term.  Another user community idea was to stabilize the connector to each pots wire harness using a dot of epoxy and rerouting the wires to help relieve stress on the connector from stick motion.
.....

UPDATE: March 18, 2011 - Today I realized that, what I thought were OrangeRx defects and servo defects, were actually due to the dirt poor quality of the DX8 radio.  I have video documentation of yet another incredibly dangerous flaw in the DX8 radio hardware uploading to youtube right now, but I wanted to quickly issue this ***** WARNING ***** to all Spektrum DX8 users to stop using this acutely hazardous radio even before it finishes uploading.  A quick web search confirms that as many as 2/3rds of all DX8s have developed similar control failures.  My faulty and defective DX8 was responsible for two crashed models that I erroneously attributed to OrangeRx failures.  I must apologize to OrangeRx and those who may have held off buying these products due to my erroneous attribution of Spektrum's horrific quality to OrangeRx receivers, which are likely fine.  The only problem I can be sure of at this point is my own poor taste in radios.  I will link the video here as soon as possible:

..... UPDATE: January 26, 2011 - I'm downgrading my rating on this radio to an F. After only a few months of solid but careful use, and waiting for busy schedules and the weather to align today, the radio failed. Some purchases seem to fight with you in perpetuity, and this DX8 has been one of them from my perspective. In my experience, most of those sorts of nagging bad deals were bargain priced equipment I wished I'd skipped in favor of higher-end equipment, but this DX8 is just the opposite--premium priced with inferior component quality, unrelenting nanny-state annoyances, in-your-face ergonomic blunders, often plain stupid and needlessly complex daily operation, software logic errors, and a demanding, needy support system that just has to know all your private information before offering relief from their own incompetence. Wish I could grade it lower. Bad reviews for this radio are all over the web, bottom line: it is acutely dangerous product and it has horrible quality control.  Horizon cust service can't keep up with all the safety problems and have gone into hiding. ..... Original review follows:
September 12, 2010: DX8 has arrived.  I will add to this review over time, as the radio reveals its strengths and weaknesses.
 
First Impressions:
First things first - the radio ships with a very serious flaw: the main roller bar is too smooth and does not have sufficient traction to make your selections easily.  Unlike the 6i, in order to spin the 8's roller positively, you have to apply almost enough down force to press it, often hitting "enter" by accident..  This flaw alone nearly rules the radio out for me.  I suspect this has to do with how much "print" one has on the meat of their thumb, but assuming all thumbs are created equal is a mistake in itself.  My thumb slips to the point where I can't turn the wheel predictably on most attempts.  I have no problem at all with my other Spektrum radio rollers.
A second major flaw quickly appears with the very smooth, thin hexagonal sticks. Again, the material is simply too slippery and the stick grips (a kind choice of words for something resembling polished Teflon) do not give sufficient tactile friction to maintain positive control.  
How could such a major release have two glaring errors in the most basic functionality of the radio?   Here's an idea: don't get creative with main controls that work perfectly well, it's only down hill from perfect. 
The poor ergonomics of the two main controls (sticks and roller) are inexcusable.  In fact, even my bundled BlitzRC radio ($30 for the 2.4 Ghz transmitter and 6ch receiver) has a much better (excellent, actually) adjustable length, knurled round metal stick grip.  And so the solution to the second  flaw is quite simple, swap the stick stalks with any $15 transmitter.  Presto, fabulous.  Unfortunately, now my BlitzRC TX sticks slip like a pig on ice skates .
If you don't mind the constant headache of frustrating data entry, and after you change-out the sticks, the DX8 is a load of fun.  There is a whole lot to like:
Two things that will immediately jump out at the DX6i crowd are the three-position rate adjustment switches and flap switch. Three-position flaps are wonderful, now you can have no-flap, combat flap and landing flap, separate takeoff and landing flap setting, or set inverted wing camber with flaps beyond "up."  More coolness is the time to motor down function--you can specify any amount time for the flap "motors" to run the flaps up and down.  Any elevator pitch interconnect or other mix is blended at the same rate.  This is an excellent feature to avoid over-speeds and abrupt pitch and trim changes.
With the primary controls' three-position rate adjustments, you can finally introduce expo with one click and travel adjustment with the other, or run them in any three-combination you please.  Setup is a tad easier than the DX6i, as switch assignment selection is an option in the same screen that tailors travel and expo, not buried in a different global menu, but that is a double edge sword as the task of assigning more than one axis to one switch is now multiplied.  More chance for user error, and Spektrum made quite a few software errors themselves (see below).
Speaking of global settings, another major annoyance is the requirement to turn the radio off to use it.  That's right, half the model's settings come up by default, to get to the other half, you have to cycle the power off then on again while holding the roller down.  Unbelievable.  Awful idea.
Unfortunately, there are a lot of model-specific settings buried in the "turn me off" menu, requiring you to cycle power off then on to change your current model's setup, such as trainer switch operation.  This is a major shortcoming, since you must unbind the currently selected model to adjust it. This is unsafe, as you cannot verify the new bind without re-opening most airplanes and verifying a steady bind light.  The DX8 software forces people to routinely unbind, possibly causing the loss of a model, or worse, injuring themselves or bystanders.  This is one of many very serious safety problems we'll see with the DX8 in this review, and one that could be hard to fix in future releases since it involves hardware (to get to the hidden menus) as well as software.  Just awful!
My guess is that the need to turn the radio off and give up your bind is to keep people from adjusting certain key settings with the model in the air.  I did that occasionally too, it can save an airplane if you accidentally set something way off.  So to save you from yourself, they kill you.  Nanny-state run amok, and another reason to dislike the radio.  Not promising for the rest of the review.  
Telemetry: It's hard to imagine a less convenient telemetry module than the DX8's TM1000, and the (not) included sensors.  In its most basic form, a voltage readout, the DX8 telemetry setup actually requires soldering a custom connector (extra parts to mate to your battery-connector are required). Personally, I don't mind conceiving and soldering-up a custom sit-between to wedge the DX8's bare wire voltage module between my battery connector and ESC connector, but to most people, this is entirely unacceptable and essentially a useless solution.  Plus, soldering a double EC3 bridge isn't without trickiness, you need a jig to act as a third hand.   And what if I want a voltage readout from another plane?  How do I move a soldered sensor from model to model in the field?  This absurdity alone gives the DX8 telemetry pack an F.
 
Better solution: Quanum's 16 gram voltage telemetry module plugs into any battery's balance connector, making it model-independent and portable; it installs quickly without any soldering.  As a result of using the balance port, the voltage readout on the main display shows each battery cell's voltage, as well and total voltage, allowing you to identify a weak cell within a battery before it bites you.  The unit shown is included in Quanum's $60 telemetry package, or it costs $30 for each additional self-binding telemetry transmitter in case you wish to leave it in a plane.  It has a wired plug to pick up the optional temperature probe with amp sensor ($20).  This is a much more mature solution that can live in multiple airplanes, cars, or boats, or simply append to any 2 to 6 cell battery, or move between many devices quickly and easily.  Oh, and it beeps, but it can't buzz :)
The temperature sensor is straight forward, you wrap it around some hot thing and plug it into the T1000.  It works well. An RPM sensor is supported, but not supplied.  Cheap. With the telemetry grade of "F" out of the way, once you spend A FEW HOURS getting everything installed and soldered (luckily I had two spare EC3 connectors on hand), the module works.  Unfortunately, the display mechanization is not good.  Not only is the DX8's back-lit (nice) screen on the bottom of the radio, a very difficult position to use for telemetry data (especially with a neck strap, which blocks the screen with or without telemetry data displayed),  the main telemetry screen is different from the flight screen so you can't view trim position and telemetry at the same time.  The good news is that the DX8's trim display is so small, it's virtually unusable during flight anyway.  The telemetry screen does have a nice, large font. Overall, you are better off buying a $60 Quanum Telemetry pack that mounts high on your transmitter's antenna for easy viewing and has a voltage relay that is not hardwired to a given model.  DX8 telemetry is a serious disappointment compared to inexpensive, more convenient and more usable solutions.  Too bad the TM1000's telemetry receiver is built-into the radio, that perpetually adds cost for those who prefer more mature solutions.
In Flight: After flying with the radio for quite a few sessions, I'm sorry to have to move the DX8 to my AVOID list until the beta testers (early buyers) are finished with it.  For the most part the radio flies excellent, very responsive and precise.  The fine trim increments more than fix the too-course trim problem of the DX6i and DX5e, which almost always left a high-throw model climbing or diving without a small enough trim click in-between.  Features are improved as well, with up to 6 Mixes and three-position rates.
Switches are numerous and have a lot more adjustment stops the the Dx6 and 7, but the toggles still feel cheap.  I have a broken rate switch on both my 6i and 5e (they won't budge).  And after only a couple of weeks use, my DX8's aileron rate switch has rotated about 70 degrees--it is now more of a left-right movement than up-down and won't easily rotate back.  Cheap, again. Much has been advertised about the easy to use software.  I find the "operating system" less intuitive and needlessly complex, but generally more useful.  For example, good luck calling up different models without consulting the manual.  Model selection is hidden and there is a secret switch combination to unlock it.  But hey, that is good because if your radio is stolen, a thief won't be able to use it because the system is so counter-intuitive.   Another example: instead of navigating to different mixes in a menus labeled: Mix 1, 2, etc., there is only one Mix screen.  You have to "know" that hidden underneath the words "AIL>RUD" are the rest of your mixing options.  Huh?  Why not call the field "Mix 1" to give you a clue there are more mixes underlying that field?  I had to go find the manual after being unable to find any more mixes in the field.  I don't appreciate losing flying time for impossible to decipher software, it's hard enough to find time to fly. Another software nagging annoyance occurs in the Expo setup.  As you set up your rates, you have to remember to assign each control to the rate switch you want to use.  This is in contrast to previous DXs, where you can universally assign, say, RUD, AIL, and ELEV to a single switch, independent of the rate settings themselves.  If you set the DX8 up without the proper switch assignment, you can't correct the problem by re-assigning your throws and rates to a different switch because changing the switch clears the setup.  Yuck!  And, surprise, it is way too easy to miss that a switch automatically reverted to the default setting when changing assignments, until your model is in the air and your rates don't work the way you planned.  Vibration is an interesting feature.  I'm not sure if I like it--it is a bit too intrusive to physically shake the radio while flying, especially if one isn't wearing a neck strap.  As a minimum, I recommend turning the radio-unattended warning to the audible warning tone only, to avoid the default vibration from "walking" itself off a table top or car bumper whenever you are not watching--another nanny error--break the radio to correct the customer.  I switched mine to "tone only."  Next thing I knew, it was vibrating like crazy balanced (a bit too precariously) on my car trunk.  Seems you have to set it for each model, by first turning the radio off to find that menu.  UHG!!   Radio operation is generally poorly thought out compared to previous DX radios, it requires more time and careful diligence to program properly, and it hides more things in the spirit of consolidating menu items which were sometimes preferable.  Even the back-light's operation was not thought through, hitting one of the two buttons to make it light up clears the timer, eliminating a key reason to light it up and again, making the radio hazardous to your model collection.  However, with the increased time and manual manipulation, come more setup combos and potential permutations.   The DX8's own battery is a 2000 mAh 4 AA cell NiMH pack that will barely last a long morning and failed far too quickly, needing to be replaced.  It hardly works in extremely cold weather anyway, common to large sections of the USA, lasting perhaps 10 mins after a full night's charge.  All NiMH batteries have trouble in such an environment.  Another huge miss for the U.S. market; a failure to do even the most basic research about your customer.  (Disastrous) Bugs and Defects: Unfortunately, today a dangerous software error almost caused the lost of an airplane.  The problem occurred while bound to my 3-channel BL Beaver project.  I noticed that I couldn't seem to trim-out what appeared to be an ever-increasing rolling tendency to the right.  The right roll was slowly getting worse over time.   Eventually, I wasn't unable to trim left anymore; the trim hit the far limit.  At this point, I had to hold significant left stick in to keep the plane flying level.  I brought the plane around the flag pole and touched down uneventfully, with the control stick close to the left stop at touchdown.  Phew! Upon investigation, I quickly discovered this near-mishap was a DX8 software logic error: Since I don't like flying 3-channel airplanes with a stick missing, I mix RUD to AIL.  That way I can use either stick to turn (rudder stick used primarily during taxi), and since the mix is additive, the effect is much like flying a 4-channel plane at least from a control input perspective.  Unfortunately, the Spektrum DX8 software mixes the channels improperly.  I checked the mix on the ground, of course, but I neglected to test the trim direction which is erroneously reversed.  Note, if you turn the associated "Trim" field (in the Mix settings) from "Inh" to "Act" then no trim is available.  Please see my youtube clip for documentation:
DX8 SOFTWARE DEFECT
This is an awfully dangerous software glitch. For now, don't use this radio.  Beta testing seems to be ongoing. Yet another serious bug surfaces when I mix AIL to RUD using the preset Mix, and assign it to the Flap switch, it is the same as assigning it to "On."  There is no way to turn off the mix.  All other switch assignments seem to work fine, unfortunately, I want the rudder to help out only when the flaps are down, not all the time. Update: all of the DX8 mixes are faulty, and some occasionally stop working.  It seems to depend on the order you program your radio as to which mixes work properly or continue to function.  Complete mess.  Lastly, the AR8000 receiver hates to bind properly.  When yout first bind using the TM1000bind button, you may get a solid bind light. After that it is always flashing.  I guess this mitigates the bind problems caused by Spektrums new software that forces you to turn the radio off, and lose your bind, to adjust certain settings, since binding never occurs properly in the first place.  Again, this is an acutely dangerous flaw that Spektrum is surely aware of, but wantonly released their dangerous product to the general public, anyway. On a good note, the radio is extremely precise in the air.  The trim works in very fine increments rather than previous, too coarse Spektrum DX radios that are unable to properly trim any high-throw plane.  The rubber hand grips feel good, a nice touch.  The back light works well, I hope there is a way to make it stay lit longer, but haven't found it yet.  The timer options are great, and can be set to tick only when throttle is applied (warning - check youtube [http://www.youtube.com/watch?v=C45Izp5qxX0] for a serious software error that can easily crash your airplane/heli with an un-commanded full nose down input at timer expiration). Conclusion This radio almost caused the loss of one of my airplanes within the first few uses.  There are more people reporting losing models due to odd or hazardous radio behavior.  The ability for users to upgrade the firmware (as long as you give Spektrum a host of your private information which they may sell) seems to have encouraged Spektrum to release a half-baked product.  The latest software release, 1.02, is reported to add a whole new set of very dangerous bugs that weren't in the original release.  Spektrum seems to be flailing in both technical and managerial  incompetence. For now, absolutely avoid the DX8.  The main controls ergonomic interface is poor, the nanny software is inconvenient and in some cases poorly or incorrectly implemented, and early bugs appear to be dangerous indeed.   After the beta testers (we early adopters) absorb the initial casualties, then decide if the ergonomic flaws and high price are worth the new features and improved responsiveness. z8rc rating for the DX8 package: D 
B+ and higher =  Highly Recommended
D+ and lower = Avoid
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