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Jul 24, 2006, 05:17 PM
Thread OP
Question

Tell me again Why I shouldn't use the DX6 Xmit for CCPM?


All,

I have a new T-rex SE that I'm setting up and I have a choice right now to use a new Rp 146i and my 6EXH Transmitter or a new DX6 rec and my DX6 Transmitter. (Don't want to try to convert another Transmitter to Spectrum at this time)

I've been experimenting with the Spektrum set up in my "Dragon Stien -45*"
and it flys pretty well and is doing what I can do at this point.

But I remember a discussion on limitations of the Spektrum Transmitter as far as CCPM helicopters goes (the reason people were converting other Xmitters,) but I can't find it.

What doesn't the Spektrum do well again?

*DS-45 = (picture I hope) started life as a Dragonfly 45 after a lot of work it still jumped around a lot. Changed to a ARK-450 mast, the S-75 servos that came with the DX6 an old Telebe gyro and a bunch of T-rex parts and a little inginuety. 486g with 1200mhr LiPo.

Thanks,

Jim P.
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Jul 24, 2006, 05:40 PM
/bin/ksh
Steve_C's Avatar
That would be because the DX6 only has a 3 point curve as opposed to other radios 6 point curves. Well, as I've read
Jul 24, 2006, 05:49 PM
I fly my rex with a DX6 and it's not so much the 3 points but the resolution that's lacking. I can fly it fine, but definately wish it were smoother, you have to have very smooth inputs with the collective. I love the 2.4 so I will eventually find a 6102 to spektrumize. After owning this system and hearing others complain about glitches and lock-outs I really appreciate the technology.
Jul 24, 2006, 07:03 PM
O'n'A Party Rock!
Basically, there's nothing "wrong" with using a DX6, it just doesn't have as many features as other heli radio, no expo on rudder or D/R rudder without some funky programming, and other issues like these that make people prefer other radios or to convert a better radio to Spektum... I use a DX6 on two copters myself, works OK, I am just beginning to see that I wish I had more settings to play with than it offers... Supposedly there is a better version of this radio coming out this fall or so, but I know noting about it...
Jul 25, 2006, 02:22 PM
Thread OP
Well, Thanks. It sounds like for what I want to do, and the stage I'm at in this helicopter flying that the DX6 will be just fine for my new T-rex SE.

I haven't noticed that lack of resolution part yet as the DX6 seems as good as the servos at the moment. Maybe when I upgrade to digital servos I'll be able to see it. (and those new DS285's look pretty interesting.)

And right now I'm sort of happy with the three point curves (vs 5 point on the Futaba) as I'm making pretty course adjustments and usually just changing the middle or the end anyway.

And of course its cheaper at $60 than the 146ip at $80 and another $15 for crystal.

And though I've never had either one glitch - I have more confidence in the DX6 (it is all in my head, but that's important too.)

Maybe that better Xmitter will come along before I need it.

Jim P.
Jul 25, 2006, 04:17 PM
Registered User
I built a T-Rex for a friend using the DX6. After using a Futaba 9CHPS for a couple of years, I felt like I had hopped into Doc Brown's Delorian and went back in time. The menus are horribly cryptic in comparison, and the overall feel of the radio isn't nearly as nice. The 3 point curves limit the fine-tuning aspect of setting up a heli.
Jul 25, 2006, 05:28 PM
Team JR/DFA, KBDD Team Captain
Ah Clem's Avatar
I am using the DX6 in two different CCPM TREX's and it works well. I am not a contest flyer and it may be that someone at that level can tell the difference.

I am using JR281 servos as I am not crazy about the S75's that come with the DX6. Perhaps the stock servos are part of the reason that some are complaining about the resolution (just speculating here).

I did have the issue with glitching (actually, going into fail-safe) that some have complianed about (both those using the Spektrum and conventional radios). This was cured by advice from this forum-lubing the tail belt with WD40 or Silicon spray.
Jul 25, 2006, 05:34 PM
Über Geek
Quote:
Originally Posted by Ah Clem
I am using the DX6 in two different CCPM TREX's and it works well. I am not a contest flyer and it may be that someone at that level can tell the difference.

I am using JR281 servos as I am not crazy about the S75's that come with the DX6. Perhaps the stock servos are part of the reason that some are complaining about the resolution (just speculating here).

I did have the issue with glitching (actually, going into fail-safe) that some have complianed about (both those using the Spektrum and conventional radios). This was cured by advice from this forum-lubing the tail belt with WD40 or Silicon spray.
Do *not* use WD40. Yikes. Silicon is what you should be using. WD40 is just for eliminating water/preventing corrosion. It has some lubracative properties, but it will also collect dust, and it dries out quickly. Just use silicon oil.
Jul 25, 2006, 07:08 PM
That tree again!!!!
thanhTran's Avatar
The DX6 would fly your Trex fine. But when it comes to precision hovering, you would find that your heli would not sit in one location very well. There are swashplate interaction when you give some cyclic control (i.e if you give right cylic for example, you would see the whole swashplate is moving up or down along the shaft - which causes change in pitch). It's not because of the 3 point curve I don't think. I don't see I have problem with that. I'm was using HS56 servos, not the S75's that come with the radio. From what I saw, if I wanted the same similarity of smoothest I had with Hitect Eclipse 7, I had to increase the DR and Expo. For FFF or looping, the DX6 works just fine. For the peace of mind, I would go with DX6 even if I didn't have choice to spektrumize my Eclipse 7. That Dx6 looks really nice by the way.
Jul 25, 2006, 07:08 PM
Team JR/DFA, KBDD Team Captain
Ah Clem's Avatar
ormandj,

Thank you. I had been warned and will stop using it. I was just commenting that it corrected the glitch.

Thank you. Any particular brand of silicon spray that I should get?
Jul 25, 2006, 07:57 PM
Über Geek
Quote:
Originally Posted by Ah Clem
ormandj,

Thank you. I had been warned and will stop using it. I was just commenting that it corrected the glitch.

Thank you. Any particular brand of silicon spray that I should get?
No problem, I just wanted to make sure nobody read that post and assumed WD40 was ok. :P

Doesn't really matter which brand, they all work the same. Just get whatever is cheapest. I bought a huge spray can for a buck or two at an automotive store. It doesn't even have a brand name on it, it's a blue can with a black top, and writing in Chinese. The only English words are "Silicon Oil". :P
Jul 25, 2006, 11:01 PM
Registered User
BTW... 3 point curves are no issue at all if you use a governor, because IMO 5 point or more curves are a waste of time on pitch... pitch should be a straight line anyway for an even feel. For governor, you just want a straight line for throttle. I don't have a traditional 'normal mode' either, I just use throttle hold for shutdown and spoolup, and rely on the soft starter.
Jul 26, 2006, 12:11 AM
Registered User
There's nothing at all wrong with the DX6 and a Trex in my opinion. I'm not going inverted yet (I'm not flying at all right now :-( ) and I've only ever used a 7ch to compare it to, so take it with a grain of salt.

I'm convinced it is the best computer radio to start with based on its simplicity, and complete lack of glitching. The curves don't bother me (as someone else said, go governor and its a relative non-issue), and I don't experience any noticeable cyclic interactions that affect my hovering (headspeed is the major component here, at least for me). I can say that although it can be done with the DX6 to some degree, D/R and expo on the rudder have me intrigued.

As far as the tx/rx communication, anything other than the dx6 technology is dark ages.
Jul 29, 2006, 05:21 AM
Registered User
It's characteristic of the web that someone somewhere makes an unsubstantiated or highly subjective claim about a product, and it then circulates and amplifies as it whooshes around. This is particularly true when it is a negative comment.

I am only a beginner but I find the DX6 fine so far on my TRex (450XL-HDE, 430LF, A35G, 3xHS65MG, GY191+HS65MG, SpektrumDX6, 3S/2200).

The safety and simplicity aspect of the 2.4GHz technology *far* outweigh the minor usability issues in my opinion. While the UI is indeed slightly cryptic, it takes only a few times using it to become familiar with the very logical abbreviations and simple navigation model. Sure, fancier Txs with bigger LCDs can have better UIs, but the DX6 is easy to learn and perfectly usable. The fancier Txs with the genuinely better UIs also have a wealth of features you may never need and these can be very confusing to wade through, no matter how good the UI. The DX6 has everything you probably need. Often times, simplicity is a blessing.

I have yet to see any substantiated reports of cyclic interactions, just lots of people saying that they heard it was a problem somewhere else.

I have seen some reputable folk commenting that they found it "slow" compared to high end (eg JR9XII or Futaba 14Mz) transmitters. That may be so, but it's hardly fair comparing a $150 Tx to a $1000 one. I have also seen some reports that a DX6102 was noticably "faster" and this was attributed to the faster CPU in the 6102 compared to the DX6. That sounds plausible but I would love to see some lab measurements about frame rates and input-to-output lags to justify it.

I also wonder about people's comments on lack of precision or smoothness. Are they comparing apples to apples ? You know the DX6 is a 1024-step system which you have to pay three times as much for in the older technology. When people make these comparisons is it the *same* heli, with the *same* servos and just the different radio ? Or are they comparing a DX6/S75 setup to a 9CHP/HS56 setup ? If the servos are different then the comparison is meaningless. I have HS65MGs in my TRex and (again, as a beginner with little expertise) the control seems pretty smooth to me. In fact even as a beginner, I fly with 0% expo on cyclic.

On the curves front, hunt around and you will find that almost all the curves that people post are either linear or two-part piecewise linear or can be approximated by two-part piecewise linear to within a % or two. For a really advanced pilot looking for really, really fine tuning, perhaps a 3-pt curve is a problem, but for mere mortals I have yet to recognise a problem with them.

So, unless you want to risk your TRex being shot down by little Johnny turning on his birthday present in his house while you are out in the park, stick with the DX6. If you get to the point where the usability, features or performance show up as a problem, you can always upgrade to a DX6102 or perhaps by then Spektrum will have a higher end Tx of their own.

So I guess by now you have figured out that I am a big fan of the 2.4Ghz technology and I think the DX6 is your best choice for now.
Jul 29, 2006, 06:50 AM
Registered User
I can't comment on Spektrum and CCPM, 'cause I've never set up a CCPM heli on it (my T-Rex is mechanical mixing).

But for everything else... what he said

I'd like to comment on the resolution: the Spektrum seems to go best with the S75s. I've seen comment that it seems slow, from people who disregarded the S75s and ran HS56s or something else instead. Maybe there's a reason they're sold with the S75s? Certainly, I get more speed and smoother action out of S75s than the other servos I have.


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