DX6 problems when used with an AR400 reciever

[Michael Oliver]

Hi all, over the last couple of weekends I have nearly lost three different planes while using the above combination.

All have been glow powered sport models and all have shown the same symptoms ie. while the models were banked in a turn, they have all shown a momentary loss of control and have rolled over on their backs, I have managed to regain control only because I had sufficient height.

The receivers show no signs of having lost the signal and when I carried out a range check afterwards they all exceed the 30M range.

Are there any known problems with the AR400 receivers or the DX6 Transmitter ? Have I done something wrong installing these receivers in glow powered models ?

Many thanks Michael.

Edited By Michael Oliver on 22/08/2015 18:02:19

[Hangar 9 nut]

I think the ar400 are dsmx which I think are only compatible with the DX6i and not DX6 !

[Pete B]

Sorry, H9n, you couldn't be more wrong

A DX6 and a DX6i of whatever age will both be compatible with DSMX and may also be compatible with DSM2 if imported and distributed before 01/01/15.

Your problem doesn't seem to me to be anything to do with the radio, Michael. Are you flying them too slowly in the turn? Remember that the stall threshold speed is higher as the wing loading increases, which it will in a banked turn.....

Pete

[Chris Barlow]

Also what RX battery are you using?

Under power in a turn you'd be using at least 4 servos if not 5. The RX pack may be dropping the voltage momentarily under load, the RX switches to failsaf & the voltage in the pack increases again and you regain control.

I use 6v 2,000mah min with my Spectrum gear as it seems very sensitive to voltage drops. Have had no problems with AR400, AR610 and AR8000

[Michael Oliver]

Thanks for the replies guys, I take on board your comments.

The voltage problem would be an answer to what happened as all the models are running 4.8volt receiver packs, and are using standard servos (futaba s3001), the incidents all happened in the first or second flights with fully charged packs, so battery drain I feel would have been minimal.

I will do some more research on suggested voltages to put my mind at rest.

[gangster]

Hi Michael Sorry to hear of your problems Just a few thoughts, The DX6 and the AR400 are a good combination They are both good bits of kit, both DSMX and work well together. (There was an earlier DX6 parkflier transmitter several years ago but I would be surprised if that would even try to bind with a DSMX TX. Spektrum have the annoying habit of re using the same model numbers)

Now as far as batterys are concerned I guess that rx supply problems for whatever reason,,and there can be many must be the biggest cause of crashes, many many more than interference which so many modellers are paranoid about.

There is a big belief out there that spectrum receivers should be run on 6 volts they are in fact designed to run on 3 volts (after internal regulation) An AR400 will continue to run perfectly on 3 volts, long after the servos have gone down to a crawl or stopped. I think the idea dates back to some of the earlier DSM2 receivers which if they saw a big volt drop due to heavy load, exacerbating the effect poor batteries,black wire corrosion dirty switch, or a lazy BEC etc etc took a long time to recover, several seconds even long after the model has planted itself.

Use 6 volts by all means, it will do the rx no harm but just check the spec of your servos, not all like 6 volts. Certainly some current JRs and some older Futaba servos wont have it at all.

How is your fail safe set? are ailerons neutral? I am concerned that this issue arose on banking turns, stall speed has been suggested ,very possible but also was it the same turn in a similar place, I am wondering if the aerial in that position was shielded by something big like a servo, battery oe engine. remember the active bit of the aerial is only about 3cms. Both those points are confounded by the fact that you mentioned 3 different models though Good luck hope you get it sorted

[Michael Oliver]

Just a quick update.

I have carried out a test on the battery voltages with the servos under load in two of the models, and the worst voltage I could get was 5.3volts, so I guess I can rule out receiver battery voltage problems.

I shall try repositioning the aerials, but after that I'm at a loss and a little worried I might not be so lucky if I lose control again.

[Paul Marsh]

Spektrum you should use 6v. End of. As said, most crashes are due to insufficient battery overhead voltage, and a 4.8v pack can drop below that under heavy load, and DSM2 took longer to recover, which gave Spektrum a bad name, when it was something else.

All 2.4 really, you should use 6v and 4.8v can be used on ignition units if you've got them spare. Also don't use old batteries, buy some new ones now, if you are using batteries a few years old.

[john stones 1 - Moderator]

I would think you're working your servo's at other times, as well as in a banked turn, 3 different models all different installations all different battery's displaying the same issue ?

I would be looking at am I doing something wrong, or is there something causing turbulence and catching me out, I don't know what's happening Michael but looking at other possible causes may help.

John

[Frank Skilbeck]

Check your switches as well, IC vibration could cause the switch to go intermittent, loss of volts and Rx has to reboot.

But 3 different planes each with their own AR400, Rx battery and switch would suggest it's something else. When you lost control did they go into failsafe (i.e. throttle to idle, providing it was set correctly), if so then it's either loss of signal (intermittent fault with Tx) or the aerials are being blanked.

Also I think the Dx6 only has one fixed Tx aerial so if you are pointing it at the Tx then it's getting the weakest signal, whereas the Dx9 has two Tx aerials at 90deg to each other.

[gangster]

3 different models and different rx/batt I overlooked that. Also probably rules out bad failsafe aeleron setting

Same place each time? Wind strength? Upwind or downwind turn?

I guess you have tested that aileron movement slowly many times just in case the tx stick pot is intermittent

[Glenn Philbrick]

I had an interesting experience of a similar nature. I have an electric lanc with an AR7000 Rx, it is about 5 years old and I have never had a problem with it. I was sorting out an issue with the electric retracts and the Rx is fitted to the wing so I connected a 4.8 pack to test the operation, each time I moved the retracts the Rx started to flash orange, it did the same with the ailerons. I then fitted a battery checker in one of the RX ports and this showed green until any operation of the servos which then brought it into the red, obviously the voltage was being dropped. I then powered the Rx from a bec and a small lipo which I use to power the lanc anyway this operates at 6v. All was good no orange lights and the battery checker stayed in the green, set at 6v. Since the early days of Spektrum I have operated all my models at 6v and since then have had no losses.

[Michael Oliver]

Hi all again,

One of the models was an old airframe/switch/3 servos aileron/elevator and throttle, but did have a new 4.8v battery fitted, when I experienced the roll onto it's back, the engine did hiccup as though the fail safe had kicked in, then the engine picked up again and I had full control over the model, this happened to the left of the patch, which on this particular day was the direction of approach for landing.

The second model was a brand new model, with 4 new servos (Futaba S3001) throttle, elevator,rudder and one aileron, new switch, new 4.8v battery flown on the same day, and I experienced a similar problem in the same area of the field, although the engine did not miss a beat this time.

Third model, was an old airframe, but with new gear,5 servos (Futaba S3001) throttle, elevator, rudder, 2x aileron, new switch, new 4.8v Battery. This was flown this Saturday, with a similar wind direction, but I had the problem in a completely different area the field, the model again continued to roll over and the engine cut (fail safe) before I managed to get the plane back under control and down in another field.

The common denominators are DX6 transmitter, AR400 receivers, and 4.8v receiver batteries. The TX has the Spektrum 7,4v Lithium Ion battery fitted and shows 8volt as I write this.

As I stated earlier, I have tested the models under load and the receiver battery did not drop below 5.3v.

[Frank Skilbeck]

Recently at our field we had an issue with a Futaba 6EX Fasst tx, it range checked OK but then had reduced range in the air, we thought initially it was a faulty Rx (not a genuine Futaba), but after swapping it for another Rx the same happened, we tried a different Tx and all was OK. We think the aerial on the Tx may have been damaged. Can you try one of your Rxs with a different Tx.

I would send the Tx to Horizon for checking. Also did you buy the Rxs from a UK shop, if you've bought them off an unauthorised source they maybe fakes.

[Michael Oliver]

Thanks Frank,

I am considering sending the Tx back to Horizon Hobby for testing.

I have doubts about the Tx having already had the wireless training board replaced under warranty.

All of the radio equipment is UK shop sourced, but who knows where they sourced from ?

[Dave Hopkin]

Posted by Michael Oliver on 23/08/2015 19:38:52:

The common denominators are DX6 transmitter, AR400 receivers, and 4.8v receiver batteries. The TX has the Spektrum 7,4v Lithium Ion battery fitted and shows 8volt as I write this.

I dont see how the RX or RX Batts can be the culprit - it would seem pretty unlikely you had a fault in all three Rx's that generated the same symptoms

I would be looking at the TX - and would send it off the Horizon if only for peace of mind! - unless I missed it you didnt tell us if you were using DSMX or DSM2 - DSM2 (the old protocol) only uses 2 spot freqencies for its "agilty" so if you were in a 2.4Ghz congested environment it could have been interupted (unlikely with 3 seperate incidents but possible)

[Phil Green]

Posted by Paul Marsh on 23/08/2015 16:10:51:

Spektrum you should use 6v. End of. As said, most crashes are due to insufficient battery overhead voltage, and a 4.8v pack can drop below that under heavy load, and DSM2 took longer to recover, which gave Spektrum a bad name, when it was something else.

All 2.4 really, you should use 6v and 4.8v can be used on ignition units if you've got them spare. Also don't use old batteries, buy some new ones now, if you are using batteries a few years old.

Sorry but I strongly disagree Paul. A correctly specced 4.8v pack is perfectly ok. If a 4.8v battery pack drops voltage under load then adding another cell isnt the answer, in fact that makes the overall voltage drop 25% worse. If it sags below the dropout voltage of the 3.3v regulator then its the wrong spec battery and adding another wrongly specced cell makes no sense. Its not about 4.8v or 6v, its about a supply of sufficiently low ESR that will maintain 3.3v + dropout under maximum load.

(discussed recently)

also, "and DSM2 took longer to recover" was actually not a shortcoming of the DSM2 protocol, it was simply that the pre-quick-connect  firmware didnt store the last used channels and on reboot had to start a new search from scratch.

 

Edited By Phil Green on 24/08/2015 01:41:31

[Paul Marsh]

Ok, you can use 4.8v if you want to,but don't blame me if your models goes in. sound advice ignored...

I prefer to err on the side of caution.

[Former Member]

[This posting has been removed]

[Paul Marsh]

ok have your way. its your model.

[gangster]

I am with Phil on this one. I am concerned that people could be lulled into a false sense of security thinking that using a 5 cell pack is going to be the silver bullet and prevent any volt drop issues.

In a normal sport model for a high current 4.8 volt battery, NiNH or nicad, to be dragged down below 3.5volts there is an underlying issue with either the battery, the switch, the wiring or maybe the servos or heavy surfaces. Overlook these at your peril, that extra volt or so may not help here.

I am not saying that you should not use 6volts if you are more confident with that but dont expect it to be the total answer and paper over the cracks. Meticulous regular check with a battery checker on a regular basis whilst waggling the sticks is a good plan.

Too many modellers are ready to blame certain manufactures kit or worse still are over confident of other manufactures kit when the real issue is closer to home. Unfortunately so many old wives tales in modelling seem to stick for ever and models crash cos real issues are overlooked

However the cause of delay in responce after blackout in some DSM2 rec must be a real issue.

For info AR400,AR610 and6210, in fact probably all DSMX are back on duty instantly power is restored. So I question the statement "all Spektrum should be used on 6V)

What voltage do I use you ask ? well all my glow models are on 35 pcm anyway 4.8V and all my 2.4 models use 5v from the esc . I do however only have one dsm2 receiver but that is an Orange which is pretty quick back on parade and its in a foam glider that probably wouldnt notice most of the time if the receiver had a few seconds rest

Just to repeat an earlier caveat make sure your servos work ok on 6volts, some wont last long/

[Dane Crosby]

I use Spektrum AR6010, AR610 and AR 7010 with my DX7s (all DSMX). On leccy models I use the 5v from the ESC/BEC. On glo models I use 2s 2200mAh Lipos with a >5A SBEC set to 4.5 on most and 6v on a larger model. Each model is fitted with a Spektrum log and so far (after two years and a lot of flying) The voltage has stayed steady and I have suffered no Holds or Fades. I must admit I have not tried the NIMH route but others in the club rely on these and I've not witnessed and issues they have suffered yet.

[Phil Green]

Posted by gangster on 24/08/2015 10:10:06:

In a normal sport model for a high current 4.8 volt battery, NiNH or nicad, to be dragged down below 3.5volts there is an underlying issue with either the battery, the switch, the wiring or maybe the servos or heavy surfaces.

Exactly. If you suspect that a 4 cell pack dips to 3.5 under load, thats almost a 2 volt drop, half a volt per cell. This means the cells are seriously underspecced. But to counteract this, instead of using low-ESR cells which can supply the necessary current, you're happy to accept this huge sag, not only in four cells but now in five - which will with the same load drop 2.5 volts - in fact it will be more since instantaneous consumption is higher with the 5-cell pack. This is not how an engineer fixes a supply problem. The receiver is a 3.3v device, it simply needs a supply of 3.3v + dropout + a confidence margin, for which a good low esr 4-cell pack is perfectly adequate. Propping up a resistive supply with extra voltage is a poor solution to a simple problem imho.

Further, to say that "all 2.4 needs 6v" is just wrong. Some have better low voltage tolerance than others, dependent on the specific regulator used, but they're all 3.3v devices and none need the > 2.7v dropout margin of a 5-cell pack.

Sorry I know this goes against the grain, but its just plain simple electrical engineering vs blind faith.

Cheers
Phil

[Michael Oliver]

Thanks again for all the replies,

I'm not sure if someone got hold of the wrong end of the stick somewhere but when I did the load test on the receiver batteries the WORST reading I could get was 5.3 volts.

The batteries are all Overlander 2000Mah Eneloop's.

This morning I have contacted Horizon hobby for there ideas, as I'm feeling the TX is at fault having had the wireless trainer board already replaced and having flown the worst affected model previously using a DX8 transmitter with no problems,

I'm thinking maybe "buy cheep, buy twice" the DX6 is very cheep for what you get, and I wonder have they cut a few corners, or is mine a Friday afternoon special.

[trebor]

What's the best way of checking your voltage drop on nimh batterys ? I've got those illuminated bar type indicators fixed in the fusalarge but all they tell you is poor, good, excellent.