Warning Graupner USA HOTT SYSTEM
 

Iwanted to share this post from a guy in the RC Jet Forum that lost over $10,000 in a crash becuase of this system and I also have lost an airplane becuase of this crap. Please Read Below this was posted by " 747junky" in the Jet Forum


"Well I feel almost responsible for this crash but I need to let everybody know that extreme caution should be used if you are operating the New Graupner Hott systems. Let me clarify this actually the USA version of the graupner Hott system. I purchased a USA version Graupner MX 20 from Graupner USA for my new Ultra Lighting. It worked awesome on the Ground and range tested ok but it locked up something fierce about 2 miutes into the flight. I got it back fairly quickly after I lost signal the first time but when I was setting up for landing the plane locked up agian and it went after doing a half loop and burst into flames. I lost everything. This system from what I am told is rock solid in Europe but the USA version for some reason is not the same in anyway. I spoke to Henry from Modellbau USA a couple months back about this system and he swore by it. When I was ready to buy one I went to him and he told me that he was not able to sell me one nor does he want to sell me one. I was very surprised and asked him why, he really did not come out and say it ( I guess becuase he is a Exclusive Graupner Dealer in South America ) but he said that the US radio were different from the Radios that he was selling and the FCC has restricted him from selling those systems in the USA. I guess he did give me a warning but I did not listen. I then found Graupner USA and asked them about this problem and they swore to me that they are indentical and the system were actually better in the states. BULL S@#T they are a bunch of liers. I contacted Graupner in Germany and told them about this and they said to me that the radios are different and that they are FCC Controlled so the signal strength is different than the European Version that are being sold in the Caribean, South America and the rest of the World. Word of Caution STAY AWAY FROM GRAUPNER USA"

RE: Warning Graupner USA HOTT SYSTEM
 

Hi!
Sorry about your plane, but you must have been mistaken! The 2,4mHz radios made for the US market are actually allowed to transmitt ten times the power ratio than the 2,4Ghz radios made for the European market! So there must have been another fault to your crash than just lack of transmitter power. Did you check your receiver batteries?
Many years ago I also experienced a sudden "brown out" when flying one of my Q-500 pylon races using a then new Spektrum DX7 radio.
Tank god I was high up when it happened and I manage to get it down in one peice but it felt like many loooong seconds before the radio funtioned as it should. Since then I have learned that it's vital to use adequat voltage/battery power to the receiver and servos!

RE: Warning Graupner USA HOTT SYSTEM
 

I'm sorry to say but you are mistaken this system in the USA is at fault. There has been the Gus crash and I also crashed the airplane with exactly the same reason the radio goes blank no signal. Unless you have a US system keep your comments to your self this guy lost over $10K in a jet and I lost. 4K jet so this thread is to warn people that there is a problem with this Graupner USA Hott system.

RE: Warning Graupner USA HOTT SYSTEM
 

So this is a bashing thread and you will not allow a friendly discussion of other possibilities? Do you know how many of these threads came out when Spektrum/Futaba/Hitec, ect. were released? And people are still flying them.

Rafael

RE: Warning Graupner USA HOTT SYSTEM
 

well know bashing from me but I have to say that I have lost a very expensive jet because of this system. This thing ranged checked fine but comletly lost signal in the air. I have contacted Graupner Germany and they confirmed to me that the FCC has restricted this radio in the US version. It took 10 emails and various phone calls and I finally got the answer from them that the US version of the Hott system has 25mw of power in comparison to 100mw in the European version. They assured me that it performs the same but I am no engineer but not sure how that is true.

RE: Warning Graupner USA HOTT SYSTEM
 

FCC lists two different version of the MX16 and MX20 Hott radios: ZKZ-MX-16-20 and ZKZ-MX-16-20A

ZKZ-MX-16-20: EIRP (mW) 22.87

ZKZ-MX-16-20A: EUT Output Power (mW) 110.92

The test were prepared by

Shenzhen Laker Testing Technology Co.,Ltd
15C,Block 1,Sunshine Huayi Building,Nanhai West Road,
Nanshan, Shenzhen, China
Tel: 86-755-86307736
Fax: 86-755-86307736

Looks like you got the first version. Sorry about your loss. If your manual states 100mW and your Tx has only 25mW or so, I would think about initiating legal action.

RE: Warning Graupner USA HOTT SYSTEM
 

This thread is so incorrect its really a shame it shows up when you search Graupner on Google.

I wish it would be removed..it is miss-leading.

I sell the MX-20's in the US and all the ones I sell are 100mW transmitters.
FCC ID ZKZ-MX-16-20A...

These radios have an amazing range and I believe the 4000meter spec.

Its a shame this thread shows up so easily.

Ziggy at MiKroKopter.US<br type="_moz"/>

RE: Warning Graupner USA HOTT SYSTEM
 

Why?

It's not incorrect what I posted:

ZKZ-MX-16-20A: EUT Output Power (mW) 110.92 (Source: FCC)

I think what you sell are 110.92mW MX-XX radios not 100mW.;)

RE: Warning Graupner USA HOTT SYSTEM
 

I doubt this thread is seen very much. Bumping it after several months of inactivity will get it seen by a handful of new people.

Searching "Graupner" I did not see this thread in the first 10 pages of results.
"Graupner MX-20" didn't hit it for 5 pages, did not look further.
"Graupner USA HOTT" did find it on the first page.

RE: Warning Graupner USA HOTT SYSTEM
 

Yet another case of what was used rather than a study of why the problem occurred
These model forums are full of em
It is a sad true fact that the less that is known about a problem - the more unlikely the proposed causes become.

RE: Warning Graupner USA HOTT SYSTEM
 

Re: Graupner Hott failures:

Some systems allow you to "synchronize" up to four servo's. They then recieve the new "command" at the same moment.
Especially if you usedigital servo's they will start at the same moment and their huge current surges will add together. This may cause the supply voltage to break down.The receiver will then initiate a "cold start up" .Allthough re-binding occurs fast according Graupner, it takes a few seconds and in the mean time there is no control.. When there after it happens again and again, it looks like you lost communication. This is not exactly true but unfortunately the result is same.....
Power supply in your model is critical when using digital servo's and FHSS systems.
A battery with increased internal resistance(too small or too old)or too thin wires or a switch with a voltage drop or... Anything that causes the supply voltage to the receiver to drop for a split second will do this. And not justy in Graupner systems!. A buffer capacitor (as big as you have room for) directly between the + and -terminals at the receiver will be a great help.
If the transmitter signal strentgh in the USA is lower than here in Europe, this will not improve the situation as well.
Ridder Jan.

Note: I consider buying a Graupner Hott system. All feedback is welcome!

RE: Warning Graupner USA HOTT SYSTEM
 

First Im not a Graupner user but I have to go with Richard in this one. Its always a damn shame to have a failure that results in a huge loss like this but the most important part is to take a scientific approach to diagnosing the actual problem in order to find a solution. Its pretty common when there is a "loss of connection" to immediately claim "loss of signal". When the model itself is a total loss its difficult if not impossible to find any clues there.
My question to the OP: Do you have any hard data that points you in any specific direction or is it just speculation that it must be signal related? I would think that if I had 10g in a model I would most definitely be running some kind of data logging system at an absolute minimum to confirm the ongoing health of my system.If there is some kind of a problem and without any kind of data its a pure guess as to what the actual source may be.Telemetry would be my option with this much invested.Ive found that generally stuff doesnt just fail.It gives plenty of warning that there is a problem and an impending disaster is upcoming.
At this point the only thing that can be done is to try to recreate the "lost signal" claim. Your going to need to monitor the RF output over time and try to confirm that for some reason the RF deck is shutting off. If it happened once it is going to happen again. Then you have something to go on. Speculation gets nowhere in coming up with a solution to cure a problem whatever it may be.

RE: Warning Graupner USA HOTT SYSTEM
 

Worst case scenario
Four or more digital servos sync'd together, and control pulses sequential or at the same time.
The momentary current draw can easily be greater than size AA NMIH or NICADS can produce with out significant output voltage drop.
2000-2500 mah batteries are not capable of supplying the needed peak current, based upon the mfrs discharge graphs for some of the popular battery packs..
 

RE: Warning Graupner USA HOTT SYSTEM
 

I would wait!

Graupner in Germany has opened insolvency proceedings recently.

Since Graupner / SJ Hott radios are designed and produced by SJ Propo (Korea), SJ could sell the radios under their own brand name anyway.

RE: Warning Graupner USA HOTT SYSTEM
 

Hi guys,

I am arrived in US 2 months ago, and i plan to fly here considering that i hve been relocated (in Houston, Texas). In Europe, I fly with Graupner Radio for long time ago. I have a MC24 in 41 Mhz and HOTT as well and a MX12 HOTT that i brought with me. It seems that MX 12 complies with FCC, but for the MC24 HOTT, definitively, it does not comply with. So i would invest in an MC32 HOTT, but i would be sure that it is compliant with FCC, and neither USA GRaupner answer me nor Graupner in Germany. Does someone know???
Thanks, otherwise i gonna buy a JETIDC16, but it would be pity.

Olivier