strat1960s

I have a DX6. One of the first generation 2.4 Ghz radios that is supposed to be glitch free.
I was practicing hovering yesterday when my heli throttled up, flew about 60 feet and then crashed. So what causes a glitch free system to glitch. I've seen video and heard stories of systems locking out at the most in-opertune moments. I had all the replacement parts needed to repair everything, but what caused it to lock me out/glitch and crash? I re-binded the TX/RX this afternoon. When the heli was set up for me the guy had the idle set to climb instead of hover or descend. I set the throttle to descend slowly (slightly less than 50%). How often do I need to re-bind the tx/rx?

Ted

stevennh

I also fly with a DX6 (T-Rex 450-SA). I have not had any problems yet (about 8 months with the DX6, I had a Futaba 72MHz PCM before that). My 72MHz setup was almost un-flyable due to glitching and I could not seem to solve it with ferrites or layout changes. The DX6 and AR6000 have been rock solid for me. I have not had to re-bind since my initial setup. I have also heard about the lock out issues, but luckly have not hit it myself. I have even flown a 200mw 2.4GHz camera on-board without issues. I really did not think that I would be able to use my video down-link on 2.4GHz right next the reciever on the heli, but it did not cause any problems.

On an unrelated note, I recommend modifying the DX6 transmitter with a switched-mode regulator (you can search for this modification). This change a least tripled my battery run time on the TX. I fly most days and can go a full week or more with one charge on the TX now.

Steve

wings 540

I have been flying planes with a DX6 for maybe 2 years with no problems

gnd2

No system is completely infallible. The DSM system of the DX6 is less susceptible to interference but it's still possible. You won't get the little momentary twitches that can happen with FM and AM, but it is possible to lose the link in which case it goes to failsafe. Sounds like that's what happened to you.

There are still several things that can cause the link to be lost. The 2.4GHz band is "line of sight" and it's possible to lose the link between the TX and RX if there is an obstruction between them. I've read some posts from people who claim they lost the link just having the heli oriented a certain way so that the line of sight was broken by the frame. Radio interference is also possible even though the problem isn't as bad as with FM and AM.

I think some of these problems are addressed by the newer DSM2 technology in the DX7 and DX6i and the dual antennae arrangement.

Still I'm surprised you had this problem just hovering. I think people have also mentioned voltage problems with certain systems, but I don't know much about that, maybe someone else will chime in.

In my opinion, having the failsafe set to climb is a bad idea. I guess they did that thinking that if interruption was only momentary that the climb would allow you to regain control when the link was reestablished. But as you saw, it can fly away on you which could be dangers. I think it's better to just have the throttle go to zero. I have mine setup to zero throttle in normal flight mode which has just slightly negative pitch.

It's recommended to rebind whenever you make adjustments to the heli in order to make sure that the failsafe settings are correct. But if you're aren't changing you setup, rebinding shouldn't be necessary.

oly_rcer

okay i'm not sure about why the loss of sig but my question is your saying 2.4 gig is line of site?reason i question this is because 2.4 is where most of the cordless phones are at and i know most ppl running around their house are far from line of site to the main phone thru walls houses and such i know my 2.4 phone will work while i'm at my neighbors next door when i'm there and the signal has to go thru 2 houses and a lot of walls.????????

oly_rcer

ps if i could get a link to the switched regulator mod would appreciate it i have a dx7

gnd2

It's an expression. It doesn't literally mean that if you can't see it that zero signal will get through. But if there's anything in the way it can reduce the signal strength quite a bit, and the effect becomes more pronounced with 2.4GHz than lower frequencies. Exactly how much it's reduced depends on things like the type of material and how much there is. Metal and I think carbon will have more of an affect than sheet rock common in house walls.

But like I said, I'd be surprised that you had this problem for a fairly close hover, but from what I've read it sounds like at least a few people have had problems, particularly with carbon frames IIRC. I've never had a problem personally but I have always had the receiver positioned so that the antennae poked out both sides of the frame and made sure that they didn't touch the frame. I'm also using the AR7000 on my trex which has a second antenna unit to help reduce these problems. I did use the AR6100 for a little while but only for some tail-in and side-in hover in my garage. I've since moved the AR6100 to my HBK2 and haven't had any problems with that either. I position the receiver in the bottom tray of the frame towards the rear with the antenna pointing out the sides.

pt40crasher

450 SE
DX7
AR7000
CC 35A
fresh battery

2nd lock out event, this one inverted 30ft up. Surprisingly little damage. Radio, and Rx going back to spektrum for evaluation.

The Hedgehog

People always jump and say it is the radios fault, but as we all know T-rex's are prone to glitching even with the use of spektrum. To answer your original question however, rebinding the TX to your heli will have no effect on whether it glitches or not, if it wasn't bound correctly it would not have worke din the first place.

strat1960s

Ok, here is where we're at as of today. (Casper Wy. on my way to Tx. lol) Actually, I purchased a new ESC. A couple of weeks back, my motor seized up on me. While I was trouble shooting and looking for the cause and a possible cure, both the motor and ESC/BEC got extremely hot. Too hot to touch. RC Tek, sent me a new motor and I sent the old one back for them to look over and send on to Scorpion. Just about everyone I have spoken to are under the belief that something in the BEC/ESC got too hot and caused my lock out. It may be safe to assume that when you have a motor go bad, you might want to consider replacing the ESC/BEC at the same time. (just my opinion though)
I was going to replace my ESC/BEC in the hotel room last night but since my POS Cold Heat soldering iron won't heat up enough to melt the solder, it'll have to wait till I get to San Antonio. I need to purchase some supplies anyways. So if the ESC BEC is actually what caused my lockout, then I'll know by the fact that I don't get locked out again........well, I may never know for sure and here is why. Before packing everything up and getting ready for my trip, I ran some "gee-golley" tests on my heli. I spun the motor up to a little less than 50% throttle and used a laser thermometer to take temp readings. See, what strikes me as odd is that I'm even able to get the tx/rx to work. My idea of being broken is that it does't work, but everything seems to be working at this point. Back to my little tests. After running for about 4 minutes the motor got as hot as 106 and the ESC/BEC was fluctuating between 150 and 160. Everyone tells me that 110 to 120 is a more acceptable temp for the ESC/BEC. From my understanding when the BEC gets too hot it cuts power to the ESC/BEC and the RX goes into fail-safe mode, which in my case was screamin down the middle of my shop then hanging a left turn around a truck, crashing into the floor and sliding under my tool box. (I re-set my fail-safe throttle level to zero to prevent the screaming down the middle of my shop portion)
So, when I get to Lackland AFB I'll pick up what supplies I need and make the ESC/BEC swap. I'll let everyone know how it goes from there.

I wander, since it's -4 outside, if I flew the heli would I need to worry about the ESC/BEC over-heating? Maybe I should be worried about wanting to fly in -4 temps. I saw some really sweet places to fly on the side of the interstate.
Have an Air Force Day!

Ted

goldslinger

I've heard that if You have the C.F. frame, that it is important not to have the antenna touch the frame. They also need to be exposed as much as possible.

I used liquid electricians tape and ran a bead with a toothpick around the rear triangular opening of the C.F. frame with it and have one antenna sticking out straight on both sides. Looks sharp.

You can get it at Home Depot in a few colors.

strat1960s

goldslinger,

I'd like to get some fuel tubing and run the antenna leads through the tubing. That may help some. I like your idea too.
Thank you for the suggestion.

Ted

Shadow99

Ted,

Get yourself one of those BUTANE SOLDERING IRONS, I bought one about 10yrs ago, and I still use it all the time. It's way better than those "inductive" Cold Heat units, just watch out were the exhaust port is, and keep it pointed away from your fingers (it's REALLY HOT)!
On your ESC/BEC, could you mount it where it could get some air-flowing over it, I stuck mine where there is a contant current of air flowing over it (from the blades), keeping it a cool 95 to 105 degrees, only the 15c Lipo packs run hotter (no air-flow under the canopy).

Rick

strat1960s

Rick,

I was going to order up a couple canopies and try cutting different holes here and there to see what kind of air-flow I can get.

I stopped at Home Depot and picked up some supplies. I'll do some soldering tonight. The weather is crappy and the roads are only slightly better so I pulled off the high way a little early. I only have a few hours of driving tomorrow to get where I'm going.

Thanks for the info.

Ted

stevennh

Make sure you have the antennas at 90 degrees to each other. 2.4GHz is very prone to polarization problems and keeping the antennas 90 deg. apart greatly reduces the chance of losing signal due to reflected and blocked RF. I have one antenna going straight back, zip-tied to one of my tail support struts and the other one goes down the landing gear. This setup has worked very well for me (no glitches and/or lock-outs in about a year of flying almost daily).

I am not sure if the DX7 has the same silly linear regulator for the 3.3v section that the DX6 has, but here is the info for the DX6. My DX6 is now the energizer bunny of transmitters after this fix!

[link=http://www.dimensionengineering.com/appnotes/spektrum_mod/spektrum_mod.htm]DX6 Regulator Upgrade[/link]

Steve