DX7 - Help
 

Today, I had my first flight every with a trainer using the Spektrum DX 7 controller.

While flying with an instructor, it seems for a brief moment, I lost all comunication between the controlller and the receiver on the plane.

Can someone please advise if this has every happened to them while using the DX7?

The club and the instructor have not got a good understanding with the DX7 controller, so they were unable to advise on a reason why this happened.

Someone suggested that it might be with the battery pack.

For those that have a DX7, please advise on what battery pack you are using with the controller.

Thanks in advance.


smo0

RE: DX7 - Help
 

G'Day Smoo,
I have a DX7, & I'm using it in a Yak 54, with the 1100Mah battery that came with the radio, works fine, never a problem.
You MUST do a couple of things with the DX7, first charge your TX battery for about 24 to 30 hours using only the wall charger that came with it.
Next make sure your RX battery is fully charged using the wall charger, for about the same time as the TX battery.
Next locate the RX's, as per intructions, & then set all controls up, & rebind.
Before you fly, do a complete range check, with the engine running, & If all is well, you should be good to go.

RE: DX7 - Help
 

alan0899

I charged the TX and the receiver for 18 hrs each.

A range check was done prior to the flight.

I binded the TX with the received, but I think I didn't rebind the the TX with the received after I configured the servo setting.

Enzo

RE: DX7 - Help
 

Smo0,

Can you explain a bit more as to what happened when you seemed to lose communication. How brief was the break, I assume that it was long enough for you to put some control inputs in that did not seem to get responded to.

As Alan said, the Spektrum come with quite generous batteries, both Tx and Rx.

BTW Alan, glad yours works OK, just about to put one into my Precision Aerobatics 30% Edge 540.

Regards

Terry

RE: DX7 - Help
 

Smo0: The manual recommends re-binding after any changes in installation. So, you may wish to do that. Also, the TX antenna can be turned from the horizontal to the vertical (it is on hinges) to accomodate the polarity of the transmitted signal to the receiver better. I suggest you rebind and then when flying, point the antenna skywards (rotate it to point up so that whey you are holding the TX naturally, the antenna looks like the diagram below).

Also, please describe what happened to make you believe you lost communications with the receiver. That will help us try to figure out what happened.

CGr.

PS: Hey Allan.. how goes it? Dick.

RE: DX7 - Help
 

G'day Dick,
Things is going great, warming up here, has been perfect flying weather, shame about work, gee it wrecks a bloke's leisure time.
Hope things are good over your way.

RE: DX7 - Help
 

G'day Terry,
I think you will need 2 batteries in the Edge, I use 2 in my Katana, I have a 1700Mah, & a 1100Mah battery, use 2 switches & 2 charge leads, much better security, & redundency. See Pic.
As long as the 2 batteries are the same number of cells, & of course voltage, it does not matter if the capacity is different.
Are you going to Warialda in November, I will be there, it's for a good cause, lots of fun & only a short trip for you, from Grafton.
Hope to see you there.
I'm off to put the Katana on charge, ready for tomorrow, (Sunday).

RE: DX7 - Help
 

Hi Al.

Yep, things are just ducky over here.

I don't know if you had been following Minnflyer's string on the 'Goldberg Protege' or not, but I bought one and put one of the new OS 75 AX engines on board, used the DX7 system. What a plane that turned out to be!! Trim on the maiden flight: zero aileron... yep, zero!!! and 6 clicks of down elevator. No rudder. Amazing, and what a performer that engine turned out to be. Brand new, at the field, fueled up the tank, choked the carb, turned the prop 5 rotations to get fuel flowing, attached the glow driver and pushed the button (Radio South driver), and used my chicken stick.. one stinking flip and it was running. I advanced the throttle about 10 clicks, removed the glow driver, and had to lean out the mixture a tad to go any further, but after a few minutes, advanced it to full, made it real rich for break-in, and did the tank that way with occasional excursions to lean for about 10 seconds then back to very rich mixture.

After I was done with the first tank, it was running so well that I chanced flying the plane. Wow.. what an engine. The take off roll was intentionally long because I wanted to make sure I had enough speed for a proper take off.. but it lifted off the ground and flew like it was on rails!!! (except for the minor elevator trim adjustment). I didn't go vertical till the next flight. I flew about 10 minutes and decided to land it. Well, I was concerned..new engine and going to idle, may have a dead stick on my hands here.. but nope. I retarted the throttle just after I made the turn from base to final and it idled down like it was supposed to, and the landing was a greaser with the engine still idling.

I picked it up and brought it back to the bench and refueled for the next flight. Meanwhile, I chedked the RPM at idle and it was 1800 !!!! Wow.. still putt-putt'ing along nicely at that slow RPM.. then transited to full throttle like nothing. What an engine!!! Highly recommend it to anyone looking for a very powerful 75 engine.

Dick.

RE: DX7 - Help
 

Hi. To further amplify what Allan was saying, I use a two battery setup on all my larger planes now. Especially after what happened with my Venus II pattern plane. I was flying, oh, three flights if I recall, and decided to check my batteries. I have a pair of 1200 mah NiMH battery packs in that plane, by the way, each on a separate switch and into a separae RX channel. Anyway, I checked one battery and it was around 6.2 volts. Fine.. another one or two flighs here easilly. I checked the second one... first the voltmeter flashed a few times then went blank. I thought it was the voltmeter, so I borrowed one from soneone else. Same thing. So, I removed the battery pack and checked it 'off-line'. It was definitely bad. I had a spare so I put that in, but the battery, only a few weeks old, was dead.

Lucky I had two batteries in that plane or I would have lost it.

RE: DX7 - Help
 

G'day again Dick,
Yeah I'm going to get a 75AX, & put it in my 60size Diabolo, it just needed a bit more power, I think the 75AX will be perfect, I'm ordering mine on Monday, thanks for the heads up about it.

RE: DX7 - Help
 

Hi Al.

Oh, it will have enough power for that plane, no doubt. You will be thrilled with the performance, I'm sure. The protege is a like the sise of the Tiger 60 and my Tiger has a Super Tigre 75 with a tuned pipe, and this OS 75 AX will run circles around the Tiger.

RE: DX7 - Help
 

Guys

I was flying on a buddy box with the instructor, I got into a bit of a situation when the instructor took control of the plane with my DX7, the plane was about 100 feet in the air, at 1 point the instructor advised that the plane was not responding to any of the inputs in the controller, eg, throttle and aileron.

The loss of communication was about 3-5 secs, enough for something bad to happen if it was at a lower altitude.

Between the first and second flight I had to change some of the travel settings on the ailerons, throttle.

Should I rebind the receiver after changing any settings on the TX.

Smo0

RE: DX7 - Help
 

I just had a look at the battery pack that came with the DX7.

the battery is a 900mAh, is this size to small to run the 4 digital servos.

Someone at the air field advised I should go no lower then a 1000mAh

Smo0

RE: DX7 - Help
 

900 mah is plenty of battey. The Airtronics I had when I started out with the Nexstar was 600 mah. You can get whatever size 4.8 you want, just make sure that where you put it does not upset the center of gravity, but the 900 mah is fine. My Protege has a 1200mah, and it has 5 servos.

Look up the servos at Horizon Hobby and take a look at the specifications. It may list average current draw. Multiply that by 4 (for four servos) and divide that into your 900 mah battery and you will get an approximate time that your battery will last. Remember, your result may be a decimal.. like .556 which is about a half hour of continuous (just an example, each situation will be different).

The best thing you can do is buy and install a Voltwatch http://www2.towerhobbies.com/cgi-bin...&I=LXHDJ2&P=ML

That goes into a vacant receiver channel and will continuously monitor your battery voltage. Obviously, you cannot see it from the air, but you can see what your voltage is before you fly and what it is after you fly so you can judge if you have another flight or not. Very good idea to use these.

Hope this helps.

CGr

RE: DX7 - Help
 

There are a couple of articles on the Horizon/Spektrum sites that talk about power requirements for the AR7000 receiver. Battery capacity IS critical with the DX7 receivers. A 900mah 4.8v battery may not be enough for digital servos depending on the load. Under high loads, if the voltage drops below 3.5v, the receiver will re-boot, giving the symptoms you described. I'm not saying that is for sure what happened, but I would do the tests in the first article to be sure.

[link=http://www.spektrumrc.com/Articles/Article.aspx?ArticleID=1683]First article[/link]
[link=http://www.horizonhobby.com/Articles/Article.aspx?ArticleID=1674]Second article[/link]

I hope this helps.

Bob

RE: DX7 - Help
 

HDsoar pretty much hit the nail on the head. Do not cut corners on the battery for the reciever on a DX7. Bigger the better! This is the area you need to go to to read up on the DX7 and learn about it. http://www.rcuniverse.com/forum/forumid_116/tt.htm

RE: DX7 - Help
 

Hold on guys. Did I miss something? Where was any mention of digital servos?

The discussion was about the 900 mah battery that came with th DX7 system. If Spektrum thought that the battery was sufficient for the included servos, then who are we to argue with that. Sure, more capacity is better, but the question was if the 900 mah's were adequate and, if the standard 'Spektrum' servos are used, then the answer to that is YES. Now that does not mean he can fly all day without charging, but he can certailly be confident that with that battery, and the include servos, and with the AR7000 receiver, and with the normal precautions about binds in the linkage, he will be just fine.

Don't put more into this than the original question presented.

As I said, I use a pair of 1200 mah NiMH batteries in three of my planes. But I also use some strong servos and am dealing with some weight and some large control surfaces.

Pattern folks typically use a pair of 600mah batteries for their 10 pound, 2 meter precision aircraft, some using digital servos. Who are we to question that success.

RE: DX7 - Help
 

Check post #13

RE: DX7 - Help
 

Hi guys

I went to the hooby shop and puchased a 1100mAh battery.

I'll be at the field next Saturday to have another go.

With regards to the charge of the 900mAh battery, I tested the charge of the battery after each flight, and the strenght of the batter was still very strong.

My instructor, who has been in the hobby for about 30+ yrs and is also the secretary of the club, double check the setup and stated that it was fine. But did not rule out the issue with the size of the battery.

thanks again.

smo0

RE: DX7 - Help
 

Yeah, I saw post 13, but that's not the original question proposed at the beginning. And besides, so what? The battery that came with the radio is what Spektrum recommends for those four servos. Do you really think they are going to supply a battery that would prove inadequate for the needs of that system? :eek: I sincerely don't think so. It becomes a matter of personal choice if a person wants to go larger than what came with the radio.

I would NOT recommend going smaller without a real investigation into how much current is actually needed per flight (as in trying to save a few grams of weight or some such thing, to gain speed or some other advantage). And then I would hang a voltwatch on this setup just to make sure there was adequate current available for each and every flight (which I do anyway).

RE: DX7 - Help
 

Nowhere in the manual does it state that they recommend that battery. Fact is, thats all they ship with it. You are more than welcome to fly your 900.......right into the ground! When the voltage drops below a threshold voltage the reciever drops out and has to re-bind and come back. Larger batteries have more reserve and are less prone to dropping below the threshold voltage under load - period! Read the posts in the JR section then come back and tell us all about the 900! You will convince very few to use minimal amperage with a DX7 around here!

RE: DX7 - Help
 

Well, that's what they make chargers for, and voltmeters. Don't tell me they won't last one or two flights because they will. And they don't have to state it in the manual.

With that said, mine still sits in the box in favor of 1200mah 5 cell 6 volt batteies.

RE: DX7 - Help
 

Quote from the manual with the Spektrum module I bought for my JR 388:-

"A hold occurs when 45 contiguous frame losses occut. This takes about 1 second. If it occurs in flight it's important to re-evaluate the system, moving antennas to different locations and/or checking to be sure transmitter and receivers are all working correctly."

Not sure if this helps but it's what Spektrum say. Don't think this is in the DX7 manual as it relates to the flight log but the AR7000 should behave the same way. Note it claims one second which is a lot quicker than the outage smo0 reported.

G'day Alan,

Got plenty of battery in the Edge (which I have already been flying with my JR 388 Tx). 2 X 1700 Lipos with an Emcotec handling the switching and feeding the servos. Had to change Tx as the 388 dropped its memory on Friday (8 years old) and I had to order another board mount battery.

BTW, whats on in Warialda? Didn't hear anything about it yet. I'm doing an instructor course at Cootamundra on 3/4 Nov.

Cheers


Terry

RE: DX7 - Help
 

G'day Terry,
It's only a Fun-Fly in Warialda, for the Westpac Rescue Choppers, lots of fun.
Hope you enjoy the Instructors course, I did mine in 2004, was fun, say Hi to Steve & Val for me. Name is Allan Asquith. they might remember me. or not.

RE: DX7 - Help
 

I don't put ANY trust into a "voltwatch", here's why: Quote from the product description: Seven LEDs 4 green for "safe", 2 amber for "caution", 1 red for "low" glow one at a time to quickly and accurately show the battery's unloaded voltage..

Even though some pilots may wiggle the sticks at an attempt to load the volt meter, this in no way can duplicate forces on the control surfaces. The only accurate way to check your battery is with a loaded meter. I prefer the Hangar Nine meter that allows measurements at .5, 1 and 2 amps.

Happy Landings