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Old Mar 22, 2013, 12:55 PM
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krafty's Avatar
France, Aquitaine, Duras
Joined Jan 2006
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Spektrum DX8 range.

Today whilst flying my old EasyStar with my 6 week old DX8, I lost all connection with the model at about 150 ft altitude and maybe only 400 feet away. The model just circled lazily with no control for about 20 seconds and then control came back and I landed safely. Prior to the loss of control the DX8 gave a vibration and also I think a musical tone but this may not be related to the failure. The only alarm that I have knowingly set is activated by throttle at 40%, set for 8 minutes. The flight time before the failure was less than 30 seconds at a guess. Sadly I was so disturbed, because I just do not have radio failures, that I did not check for a blinking light on the receiver. The model has only 2 servos and a controller with a 3 amp bec, so a brown out is unlikely. The model has flown for many years with a variety of radios, the last 4 or 5 years being Spektrum. I have been a radio flyer for 50 years!

Back home I sat the model on the grass and did a range check with the DX8 transmitter, getting a disturbingly low 12 to 15 paces before control became unreliable. I checked that the transmitter was set to EU setting and not France, though this should make no difference to the range. The battery voltage was 8.2 volts. I then bound the receiver to my trusty DX7 and with the model in exactly the same position I got fed up with walking when I still had solid control at 45 paces.
My DX8 has firmware V2.06
Question. Is there an alarm on the DX8 that I am unaware of that the vibration and beeping was warning me of. [My DX8 does not have telemetry].

I have now done a DX8 range check with a completely different model and an AR6100e receiver and the range check gave 9 paces!

I have put the old HiMh battery back in the DX8 and on charge, just to be sure I do not have a battery fault.

My conclusion is that I have a faulty transmitter.
Any comments would be welcome.
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Old Mar 22, 2013, 01:55 PM
AndyKunz's Avatar
Illinois
Joined Sep 2001
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Sure sounds like you want to have it serviced. Those very short ranges are consistent with the antenna being disconnected inside. If that's the case they have to replace the RF module because it can damage the components - in other words, don't try to fix it yourself.

Andy
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Old Mar 22, 2013, 03:54 PM
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krafty's Avatar
France, Aquitaine, Duras
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Quote:
Originally Posted by AndyKunz View Post
Sure sounds like you want to have it serviced. Those very short ranges are consistent with the antenna being disconnected inside. If that's the case they have to replace the RF module because it can damage the components - in other words, don't try to fix it yourself.

Andy
I will send it back to Horizon Hobby in the UK. They have dealt with other minor Spektrum items in the past with a service totally beyong criticism. Just glad I kept one of my two DX7 transmitters as a spare.
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Old Mar 22, 2013, 04:28 PM
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Canada, ON, Ottawa
Joined Feb 2006
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Quote:
Originally Posted by krafty View Post
Back home I sat the model on the grass and did a range check with the DX8 transmitter, getting a disturbingly low 12 to 15 paces before control became unreliable. I then bound the receiver to my trusty DX7 and with the model in exactly the same position I got fed up with walking when I still had solid control at 45 paces.

I have now done a DX8 range check with a completely different model and an AR6100e receiver and the range check gave 9 paces!

I have put the old HiMh battery back in the DX8 and on charge, just to be sure I do not have a battery fault.

My conclusion is that I have a faulty transmitter.
Any comments would be welcome.
Clearly you have a faulty transmitter.
In six years of using Spektrum (and JR) DSM equipment, I have never had less than 30 paces and normally get much more, except with one faulty (non-Spektrum) receiver.

I can also say, with a high level of certainty, that if I get 30 paces with a reduced power range check, I will have ample range for normal visual flying.

What sort of ground range were you getting when you first got the transmitter?

By the way, voltage doesn't affect range, down to the point where the transmitter stops working.
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Old Mar 22, 2013, 05:32 PM
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France, Aquitaine, Duras
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Originally Posted by Daedalus66 View Post
What sort of ground range were you getting when you first got the transmitter?

.
I was getting the normal range, which means with Spektrum receivers about 30 to 40 paces but with Orange or Lemon a bit more. But today I was flying genuine Spektrum.

Now here is something else. The last thing to try was to swap the LiPo back to the NiMh battery that it came with. As soon as I put the NiMh back I get vibrations and beeps and a low voltage warning and the TX switches off before I can do anything. So I put it on charge believing I have a low voltage and after a couple of hours the same thing happens. I realise that I need to tell the TX that it now has a NiMh not a LiPo, but I don't have time to make the change in the menu before the thing switches off. Eventually I manage to do it before shut down and of course all is ok, no more beeps and rattles. But I thought the TX was supposed to auto detect what type of battery is in it. Or is that just the charging that does that? I suppose I could have changed the battery type before taking out the LiPo, but would it allow that?
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Old Mar 22, 2013, 06:45 PM
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No auto detect. You have 10 seconds to do it. You can do it! All you need to do is get to the prompt and open it (click) and that will disable the alarm for as long as you need.

Andy
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Old Mar 25, 2013, 05:47 AM
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France, Aquitaine, Duras
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Quote:
Originally Posted by AndyKunz View Post
Sure sounds like you want to have it serviced. Those very short ranges are consistent with the antenna being disconnected inside. If that's the case they have to replace the RF module because it can damage the components - in other words, don't try to fix it yourself.

Andy
I phoned Horozon Hobby UK this morning and I was disappointed with their advice. They said for me to open the DX8 and if the aerial connection has disconnected I should reconnect it and then do a range check. If all was well with the range that is all that is required. I told them the DX8 will be sent to them so they can fix it and then I have no infringement-of-warrenty problems. I have always been very impressed with their service up until now and I hope they do a proper repair. Glad I still have my DX7 transmitter to keep me going.
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Old Mar 25, 2013, 06:18 AM
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Joined Aug 2008
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They were just trying to help you to avoid being without your radio. Opening the radio does not infringe on the warranty, HH has proven this over & over.
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Old Mar 25, 2013, 09:46 AM
AndyKunz's Avatar
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If the antenna is disconnected, you definitely want them to service it.

Andy
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Old Mar 25, 2013, 11:43 AM
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keris's Avatar
Malaysia, Perak, Taiping
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Hi Krafty just open the radio take a picture first see antenna wire it is plug right or not.If not plug right push it slowly back in my friend also have this problem when we open the radio we can see the antenna connector(gold colour) not plug in right so my friend push it back everything good after that.
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Old Mar 25, 2013, 11:47 AM
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Illinois
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Operating the transmitter with the antenna disconnected can cause the amplifier to burn out. This is not an easily-detected condition that results in greatly reduced range (hundreds of meters vs. thousands of meters) that can really only be detected with proper equipment or by sudden loss of control in the air.

Please, if the antenna is disconnected, DO NOT RE-ATTACH IT. SHIP IT TO HORIZON FOR REPAIR!

Andy
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Old Mar 25, 2013, 12:57 PM
Radio? Screwdriver!
United Kingdom, England, Bristol
Joined Aug 2011
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Quote:
Originally Posted by krafty View Post
I phoned Horozon Hobby UK this morning and I was disappointed with their advice. They said for me to open the DX8 and if the aerial connection has disconnected I should reconnect it and then do a range check. If all was well with the range that is all that is required. I told them the DX8 will be sent to them so they can fix it and then I have no infringement-of-warrenty problems. I have always been very impressed with their service up until now and I hope they do a proper repair. Glad I still have my DX7 transmitter to keep me going.
I would strongly recommend that you send it back to Horizon for repair. Running a RF module without an antenna (especially for a lengthy period) can damage it. The damage won't be immediately obvious as it happens progressively the longer with no antenna.

A sort of analogy I could give, is its like running a hair-dryer who's fan has failed. It'll try putting out energy (i.e. Heat), but as there is no fan pushing that energy out, it'll overheat and damage it.

The other thing is that semiconductor driven, RF circuits are especially static sensitive. Usually for devices with external antenna connections (i.e. WiFi routers, etc), it'll have output protection from static damage. However as the DX8 antenna connections are all internal, it may not have this protection (would be no need). So unless your properly grounded, you could end up damaging it even more. Like having no antenna connected, static damage is progressive. Plus the amount of static energy required to damage a semiconductor is a lot less than a human would feel.

Finally, Andy is one of the Spektrum developer guys - so if he says that it needs repairing, tell Horizon support that he sent you!

I'm a bit surprised that a UFL connector would have come undone. Those things stay pretty well attached (even when shocked applied), unless physically yanked off (not likely when the connections are all internal) - or if they haven't been connected properly out of the factory (QC issue?). Alternatively, the connector could be loose/faulty, so if even if you reattach the antenna, it could come off again!

Andy - Its also surprising that HH support advised for a user to reconnect it. Apart from the damage due to no antenna connected, there is real scope for damage to the RF module through static damage (would the average user ensure he's properly grounded?). Maybe its worth firing a memo off to your support guys on this?

Hopefully its not one of those things that the support guys have been doing for years without asking the engineering team for advice...!
(I say that, because I know from experience this often happens in many companies - big and small!)

Si.
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Old Mar 25, 2013, 01:38 PM
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Already done, Si.

Thanks.

Andy
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Old Mar 25, 2013, 04:36 PM
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krafty's Avatar
France, Aquitaine, Duras
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Quote:
Originally Posted by AndyKunz View Post
Operating the transmitter with the antenna disconnected can cause the amplifier to burn out. This is not an easily-detected condition that results in greatly reduced range (hundreds of meters vs. thousands of meters) that can really only be detected with proper equipment or by sudden loss of control in the air.

Please, if the antenna is disconnected, DO NOT RE-ATTACH IT. SHIP IT TO HORIZON FOR REPAIR!

Andy
I trust you implicitly and the DX8 is already on its way to Horizon Hobby UK. If they do not replace the rf unit after what you have suggested, I will not be happy. But what more can I do than send it back? They already said that if I reconnected the aerial and the range was ok, there is no more to be done. It does not fill me with confidence despite their previous excellent service.
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Old Mar 25, 2013, 04:43 PM
Radio? Screwdriver!
United Kingdom, England, Bristol
Joined Aug 2011
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Quote:
Originally Posted by krafty View Post
I trust you implicitly and the DX8 is already on its way to Horizon Hobby UK. If they do not replace the rf unit after what you have suggested, I will not be happy. But what more can I do than send it back? They already said that if I reconnected the aerial and the range was ok, there is no more to be done. It does not fill me with confidence despite their previous excellent service.
As I already have said, tell them that Andy Kunz on RCGroups said the RF module needs replacing. If necessary point them to this thread!

In fact Andy may be able to send them an email/phone directly to remind them about your particular radio. It looks like there is a Memo that will be going out to reiterate it to their service team anyway.

Si.
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