Hello everyone,

I am tinkering with the APM 2.0 that I bought and planning to follow the hardware in the loop simulation as per the below wiki


I have the mission planner and the xplane trial version loaded on to my computer. However, I realized that I need to buy the Remote control for this to work. 

  1. Which RC should I buy? I know that there could be many options but I'd like to buy something that I can finally use when I buy my airplane. Is this a good one for now https://store.diydrones.com/product_p/rc-spektrum-dx7-01.htm ?
  2. The picture in the wiki link from above shows a "Receiver" that is connected to the APM via a PPM. Is this something I need to buy separately or is it part of the APM that I already bought?

thank you for your time!


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The Turnigy 9X is a good system and way cheaper than anything else out there.  So unless you want to pay a 10,000% markup on your gear it's really your only option.

Thanks Jake for the suggestion. I will definitely check Turnigy. Do you know if I already have the receiver with APM or should I buy that separately?

The APM does not have a receiver but the 9X comes with one.

Thanks very much Jason

I would highly recommend also getting the FrSky module/receiver, smartieparts.com board and change the firmware to er9x. The FrSky make setting up a fail safe easy and the er9x makes setting up the radio for the APM a whole lot easier. 

Grr, forum just ate my rather long post.

My advise is do some googling on 9x problems. There is a reason why it's the cheapest radio on the market, why you pretty much MUST replace the RF sections with FrSky modules, why the wiring and connections inside to the potentiometers on the sticks might fail.

Further, why buy the cheapest radio, have to upgrade it, and still run the risk of crashing the aircraft where the real money is at. I mean the APM is $200 in the air plus whatever else, but you fly with a radio that costs less than the APM?

YMMV and lots of people fly with them. There are also lots of reports of those who used to fly with them. Luckily you have a choice in what radio you buy.

Just today http://diydrones.com/forum/topics/flyaway-hexacopter?xg_source=acti... 

yet another 9x flyaway. Yes, it's preventable. FrSKy module and/or the modded PPM firmware might have prevent this.

I use mine stock.  Works just fine.

Obviously the radio that sells 100 times as many units as the others is going to have more problem reports.  By the same logic I could say that there's more positive or no problem reports than any other radio so it must be better.

I picked the 9X because it reflects a reasonable markup on the hardware, there are millions of people using it, and I can load my own custom firmware. (which makes it the most powerful radio on the market, by far)

I just can't see paying a 10,000% markup when the 9X works just fine.  I try not to support companies that gouge you just because they can.  Sure they may use a $2 pot instead of a $1 pot, and if you're lucky it will actually last 10 years instead of 5 years, but why should I pay hundreds of dollars extra for this?

If they released the firmware, which might allow it to be almost as good as a 9X, I'd consider spending the extra money.  But they don't care one bit about their customers and just want to rip you off.

I think the main reason people spend 5x as much for other transmitters is that the Turnigy 9X is always sold out!  It's hard to get one as they sell out within minutes every time the warehouse gets another order in.  In fact, they're sold out as I'm writing this.  They just can't make them fast enough.  That should tell you something.

What it tells me is that they are cheap period. #1 question by new members is how cheap can I get into the air? In order to sell a radio that cheap, they need the cheapest components as you stated. When they cannot buy them that cheap, they can't make the cheap radios and thus there is a shortage. As you stated, lots of people buy and fly with these.

Cheap doesn't need advertising. Thus, even if I said nothing and two radios are side by side on the shelf and per the label, meet the requirements the user thinks they need (this may not be the be what they actually need, but that's another story), the user buys the cheap radio. We know this, there is nothing new or exciting about that fact. What I am getting at is that to this day, the instructions don't say, "If you have a 9x and do not flash the PPM firmware or use an FrSky module, you are at extreme risk of a flyaway)". So, again new user buys a 9x, because he hasn't seen or heard the stories, the instructions say nothing about setting failsafes  (which don't work anyway on a stock 9x )before you ever even try to fly, and they just don't know any better. They never range check it and the next thing you know, it's the ,"Oh crap, I just lost $600+ that flew away" post we get every couple of weeks. After much haggling and Jake's insistance that it's not the 9x radios fault, it still doesn't help the new guy who is out $600 and has the cheapest radio in his hands as the consolation prize. Jake isn't going to buy you a new aircraft and certainly isn't going to retract his recommendation of the radio.

I'm not advertising or selling anything else. I'm just trying to give some facts. And the upgradeable firmware? Seriously, this is your selling point? How about a radio that works out of the box, requires no upgrades and actually has a failsafe that works with the APM? Seriously, a radio that it's recommended to replace the entire RF transmitter and receiver to use it reliably? Somehow that makes sense to save a buck? Because it's sold out, it must be good?

Again, if the new guy wants to build his own radio, flash his own firmware, and upgrade something hoping to make it better than stock, sure, 9X is a choice.  I'm trying to give researchable staements and reasons behind my claims of why I feel it's not worth the implied savings. If you crash because of it, did you really save any money?

Further, let's hash out this upgradeable firmware. For all radios that we use with the APM, we do not use any channel mixing or other functions. In fact, those features screw up and don't work with the APM. All the user needs is straight functions and channel reverse switches because everything is handled in the APM. The added failsafes don't work with the stock receiver, they only fool the user into thinking that they do. So my question is, how is that a selling point? It's like great, I was able to hack my firmware and my radio now displays Packman on the LCD when I'm bored, but is still made the cheapest parts you can buy in China. That doesn't help you fly.

I mean I get it, we like hackable hardware. We like feeling we can get something cheap that's still OK. My point is, the control system for an aircraft with $5-600 in the air is not the place for hackable firmware or cheap parts. We want something that works out of the box, so the new guy can worry about the aircraft, settings, and other stuff, and depend on the radio to do it's job.

While you claim that's the case with 9x (it works fine for you), it doesn't help the guy in the other thread who just lost his entire aircraft. He's also not the first one, so the pattern exists.

If they released the firmware, which might allow it to be almost as good as a 9X, I'd consider spending the extra money. But they don't care one bit about their customers and just want to rip you off.

I don't know exactly when you stepped into the Hobby, but Futaba, Airtonics, JR, and others were the big players and charged huge money for the multichannel radios in the day. Reasoning was that the sensors and narrow band TXs required lots of tuning and test equipment. Then Spektrum took the market with 2.4 GHz radios cheaper than anyone else was offering. They were looked upon as the cheap guys and had the uphill battle of proving they were as good as the other guys who charged 2x the price. Now, suddenly, a cheap and initially poorly done copy (9X) came out for the bare bone price. It's made with he cheapest components that probably are rejects from better sources. And you are bashing them (assuming Spektrum and others) saying they don't care about the customer? Because they don't release the source code? Because they don't want you hacking a flight control system?


Look, I'm always open a good discussion, but your argument doesn't hold any weight. I'm not saying expensive garantees you wont crash or is better, but the only thing that can be said about cheap is that you know it's a crapshoot. Maybe you get a good one, and maybe you don't.

I have upgraded my 9X and I'm very happy with it! Sorry if my opinion upset you but thats why it's MY opinion. 


Sorry, didn't mean to insult in any way. You are at least using FrSky upgrade module which as I stated, is a valid work around to prevent the fly away scenario. Both Jake and Monroe use the stock receiver and didn't say if they use the alternate PPM firmware. Let's hope they do?

So unless you want to pay a 10,000% markup on your gear it's really your only option

I just didn't like the first post of recommending the stock 9x (not really leaving room for any options), no upgrades mentioned, no mention that you are best advised to use alternate PPM firmware with the stock receiver. I think that's setting someone up for failure. The punch in my face was that right after I read that, the report of the most recent flyaway related to a 9x radio was posted. That pissed me off because we failed to help that person prevent that accident. We know how to, and they just never got the info in time.

New members have enough trouble trying to figure this stuff out. The initial question was about if the receiver was included and if not, what should they get (hint, hint, they didn't read or understand the description on the product page). Popping off with 9X and bashing everything else, while not mentioning a known safety issue, IMO, is not the best first post to a new member. Just by the question, I would think the interaction with PPM and the failsafe might be an advanced topic to this person. Thus, selling them on a known combination that has caused 2 flyaways with no other explanation isn't our best foot forward.

All I'm asking is that if you recommend 9x to a new member, at least mention that it's a good idea to minimally look into and test the failsafe before they fly since there is a known problem. Had someone done that, 2 people might still have their machines. If that makes me a jerk, then so be it.

Vernon, you're right.  I should have mentioned that you should flash the new PPM firmware.  However, I have suggested rather loudly that DIYdrones should post a warning about this issue.

I have told them to post something on the main page, a sticky on the forums, a note with every new APM board until they come stock with the new firmware, and I have also told them they should email every person who has ever purchased an APM to notify them about this dangerous bug.

I think I've done everything short of pasting a boilerplate warning every time someone asks what TX to use.  I didn't write the flawed firmware, nor profit from it's sale, so I think I've done more than enough on the issue.

In fact one friend got banned here and another belittled and insulted due to our discussion and publicizing of this issue.  I myself even got suspended somewhat in relation to this.  So I have tried to not get myself embroiled in it anymore.

I hope you will quit blaming the 9X system for a known design flaw/bug in the APMs PPM encoder firmware.  It has been fixed with a new firmware upgrade, and if the APM is still shipping with a faulty firmware that ignores the failsafe mode of the most popular transmitter on the market... well I don't know what to tell you, it's not my problem.

All I can say is that the 9X works great.  Considering how many are sold, there are relatively very few reports of problems with them, certainly no more than I would expect for any normal piece of consumer electronics.

The only problem I've really heard people bitching about is that sometimes the pots wear out after years of use.  Most of those reports seem to say that the users have gotten hundreds of hours of use before having problems.  Others seem to use them without ever having problems.

That doesn't justify spending hundreds of dollars more on a unit that may or may not actually be any better or last longer than the 9X.  My unit has already lasted long enough for me to highly recommend it.  If it eventually fails on me or a pot goes a little sketchy I'll just buy a new one.  And I can do this many, many times before I'll have spent as much on an expensive unit.  

To the OP... the "flyway" problem was discovered by Kevin (now banned), Zen, and myself earlier this year.  When the 9X system loses radio connection it holds the last settings on every channel, except the throttle channel which it drops entirely.  This is standard, logical behavior designed to freeze the control surfaces and disarm the motor.

The flyway problem is caused because faulty PPM encoder firmware on the APM does not detect that the throttle signal has been dropped and instead steps in and injects a signal on the now dead throttle channel.  This has been known to cause quads to fly away if a high throttle was the last signal received.  They just take off and fly up and away to eventually crash who knows where.

At first there was denial of the problem, then it was said to be a "feature", and finally it was admitted to be a known design flaw or bug.  A new PPM firmware was written and the problem is now fixed.

I should probably have mentioned this when recommending the 9X, but I assume they are now shipping with the fixed firmware and it should be a total non-issue.  I suggest you try the firmware upgrade just to make sure you have the new version loaded for the PPM encoder.   BTW this is the "PPM encoder firmware" and not the regular firmware that updates from Mission Planner.

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