Brown outs and Grey areas - the truth!

[Tim Mackey]

Thanks Brian - I chose the box size for the screens to be representative of an average fuselage dimensions around the area that the receiver would be likely sited. I did wonder about the open end allowing stray signals in, but still felt that it still demonstrated quite remarkable ability of these little units - and should help dispel some of the scaremongery stories that abound regarding the poor receiving ability of 2.4G stuff, such as clean line of sight required at all times, anyone walking in front of you will cause you to lose signal, pointing the aerial staright at the model will result in sudden and certain death etc!

I am not suggesting that these "rules" be ignored, or that they have no merit at all, but blimey... I was impressed with the test results

I think that if one speaks to the vast majority of 35Mhz die hards, and suggests to them that the 2.4Ghz receiver will still work in the circumstances I have shown, they would never believe it.

PS I was also well impressed with the low voltage capability of the unit - actually BELOW the 3.5V minimum spec! 

[Rick Tee]

Great stuff Timbo, many thanx for your hard work.

[Andy Harris]

Dear Thread:

 I believe this thread shows that voltage is unlikely to cause problems.

 However I believe there may be software problems in some Specktrum kit, and the restart-recovery time is about 2-3 seconds.

 On my third flight of a Graupner Saphira using a 7100 and DX7 it went failsafe at a distance of 160m (I walked it to check)  I regained control for a few seconds only for it to go failsafe again and finally crunch outside the flying field.

I was using a 4s Battery and Turnigy UBEC. Range testing gave 80m.  We tested the 'wreckage' at the field and found no problems, Its been tested on the bench with no problems.  The installation was 'text book'.

The Saphira has been re-fettled and a JR 35MHz RX has replaced the 7100.   Same batteries, same BEC and ten happy flights so far.

In further evidence:

    7100   brand new.

    DX7i   Ebay purchase (un-marked, previously used for helicopters)

    Saphira has a slightly metalic colouring to the bottom of the canopy

My trust in Specktrum has been dented, and I of all people like a bit of new technology.... regards Andy

[Tim Mackey]

Hi Andy sorry to hear of the crash -  a couple of questions please

Why would you use a heli receiver on a fixed wing aerobat ?

I did not realise that the new DX7i was even released yet - especiallly over here?

You say you got yours from Ebay, are you absolutely sure that it was A1  - and is it CE marked?

Did you have the satelite extension rx into the main Rx? 

What makes you think there are software problems in some of the kit ? - QC of course is only relevant to brown outs, not signal interruption or loss, which sounds like what you suffered ?

A restart / recovery time of 2 -3 seconds following signal loss would not be unusual surely?

Again... bad luck mate.

[Andy Harris]

Timbo

  Ooops double mistype, have the items on the desk in front of me now.

    DX7 (Heli but thats only the logo), Has the CE logo on it. Has all the same menus, Was all helicopter names from the previous owner.

    AR6200 (DSM-2)

    Had the Satelite RX on an 90degrees (both axis) to the main, as per text book.

 It has the feel of software problems because the LEDs are not flashing in the way I'd expect.  On test the LED lights up to show a bind.  Then do a range test until signal loss LED flashes, rebinds LED goes on (my reading of the manual is that it shouldn't, it should remain flashing to show you at the end of the flight that you've had a glitch).

On crunch recovery first thing I did was open the canopy, expecting to see flashing LEDs, the LEDs were out but the servos were humming.

Bench test, LEDs on on bind, LEDs off when TX is switched off (rather than taken away).  The bind time from 'cold' is about 2-3 seconds which feels like a 'reboot' happened mid flight.

On the day of the crunch I did turn of the TX, but the model was 200m + away behind two large hedges and in the middle of a running track with a grandstand in the way (worst possible place in terms of club reputation!!!)

The DX7 is now a buddy box TX and is behaving perfectly in that role.

All the experienced chaps at the club made much sucking of air and general berating for leaving the 35MHz church.  This thread virtually rules out power problems.

So I'm at a bit of a loss and the posh kit sits on the desk .. 

[Frank Skilbeck]

Andy

I have a DX6i and so far have had approx 50 flights in 4 models (all electric inc 2 EDF) with 6100 and 6200 Rx's and not had a hint of a problem.

The LED's will only flash after a flight if you've suffered a power loss not a signal loss.

The bind time from cold, i.e. when you switch the Tx on is the Tx searching for 2 clear channals before it starts to transmit. If I switch my Rx on and off then my Rx reboots instantly. Also Timbo's tests showed that when the RX lost signal it rebooted almost immediately.

Could it be that your Tx is faulty, i.e. switching off and on, which is why it would have to reboot,  maybe you should send it to Horizon for checking. 

[Tim Mackey]

Hmm... shame about the duff information there James...I wouldnt have spent my time researching the TX and Rcvr you mentioned otherwise

Anyway..."Ooops" style apology accepted

I think Frank has summed up the explanation of difference between signal loss and power failure well enough in his reply. I also am leaning toward this being a signal failure of either Tx or reception.... as with ANY electronic equipment there are literally thousands of delicate components and systems which could fail - wiring, switches, battery connections etc etc. How sure are you that the Tx is sound in every respect? I agree with Frank - send it off for checking, but do NOT blame the 2.4Ghz system per se - and ask your 35Mhz die hard buddies to show me a long term user of R/C equipment who has NEVER suffered a glitch or malfunction of some sort, and I will show you a liar. We ALL take a risk EVERY time we fly, and should all say a small prayer to the RC gods every time we get any model back down in one piece safely...there is a heck of a lot of very complex stuff going on all the while we fly, and sometimes, our luck just runs out, and we dont always get to find the real cause.

[Jack Bagley]

Hi Timbo and friends,

                                       Absolutely fascinated by this thread! I can put my hand on heart and say, I still  fly my models into the ground all by myself on occaisions without the kind assistance of the gear manufacturer! It's all in the thumbs dear hearts I think!  Anyway, I have a legitimate excuse these days, AGE!!!!!

 Seriously though, I have read the reports, tests and experiences with open mouthed wonder and thought to myself, "Wow, what have I been missing? I could never imagine myself getting so involved with heart attack provoking worry about stuff and things going so technically wrong whist flying. I'm in the category of build it good, prepare it good and just FLY. My inner self discipline takes over and on auto pilot, charge the batteries, prepare the fuel, check the plugs etc, etc, and in the main it all goes together pretty well, but on reading this thread, I'm going to have to drink an extra glass of claret before letting my model get airborne!!!

  All the very best to you all, Jack

[Tim Mackey]

Oh dear - sorry Jack I didnt intend to worry you !! I am sure your approach is sound, and if everyone I knew had the same disiclpline when it came to building, prepping, and flying, then I am sure a lot less "accidents" would happen

I am sure you know that the purpose of these rather extended tests was more practical than scientific - I cant be doing with too many graphs and calculations - it was also borne out of a "discussion" which I was involved in on another thread regarding the apparant problems of brown outs and power requirements of the spekky stuff. various people chipped in alaong the way with suggestions for various other scenarios and tests, so I tried to oblige.

I would finish by saying that I personally have no worries at all about using my Spektrum gear, having never suffered any problems with it whatsoever - which is more than I can say for my 25 years with 35 Mhz gear!

happy - and safe flying to you Jack  

[Jack Bagley]

Hi Timbo and friends,

                                        Many thanks for your very kind words Timbo, I shall just carry on as usual then!

My confidence in method and discipline is now reassured!  I'll see what happens next time there is a weather break, it's just been so bloody awful over the last few weeks that my thumbs seem to have frozen  in the "lock up" mode.

             All my very best wishes to you all, Jack.
 

[Darren Hill]

Hi Timbo,

Reassuring tests...

I have a DX7 with AR7000 and AR6200, both of which have more range than my eyes.

My friends with DX6i's have pointed out that the geographical zone can be user set on their TX's. I have  a fair amount of experience in long range WiFi applications and equipment purchased from USA is invariably 2 or 3 times more powerful than its european equivalent. They have suggested that if range becomes an issue, try setting the user zone to USA. This could potentially increase the output of the TX. However I have no way of testing this theory. Maybe you could shed some light on this.

 Regards

Darren Hill

[Former Member]

[This posting has been removed]

[Tom Doyle]

Dear Timbo and All

Really interesting and confidence boosting read this latest thread as I'm about to embark on 2.4 for all my electric models for now - too expensive to convert everything all at once. The reason is I recently lost a Siren hotliner ( it was this seasons best model for me, gave maximum grin and wow factors) to, at the time, possible interference. Although, on quiet reflection after the event, flying at right angles to a vicious cross wind, above high trees, could also (most probably) have been the cause of my sad loss. Nevertheless, the decision has been taken to start the 2.4 conversion.

As it has taken me the best part of 5 years to understand my FF9, and still learning, and I like all the features it has to offer, I've decided to go down the Spektrum module route hoping I'll have the best of both worlds. Do you think your test results would apply to this set up too? Has anything been written by you knowledgable guys about Spektrum/Futaba combinations? I suppose I'm looking for some reassurance, after the event, that I haven't done the wrong thing. Like our friend Jack Bagley, I'm a 'plug and play' flyer having first ensured my model and equipment are prepared to the best of my ability.

One of my concerns with my chosen approach was continually interchanging 2.4 and 35 modules, bearing in mind the delicate pin terminals. My solution, albeit slightly more expensive but then I do like my FF9, was to buy another FF9, keeping one for electric and one for IC. To this end, I have acquired a little used FF9 Super with all the trimings for £150 - a bargain me thinks!

It's great to know there's so much experience out there to help us lesser mortals. Keep up the good work.

Regards

 Tom D

[Tom Doyle]

Oh dear, should first have read the previous thread 'Which Radio Should I Get'. It  covers a lot of my concerns but does raise even more. One of Timbo's minus points says "no model match". What exactly does this mean? Also, someone else mentions that "if it's not an integrated system, you won't get all the benefits 2.4G has to offer". If anyone has the time and patience to explain these points to a newcomer, or point me in the direction of some suitable reading, it would be appreciated.

 Many thanks

 Tom D

[Ultymate]

Hi Tom,

             The Spektrum/JR sets have "model match" which means when you switch on if you have not got the right model selected on the T/X then the model will not function whereas on a Futaba set as now the model will work but maybe not in the correct way i.e. some of the controls may be reversed etc. The integrated system that Timbo refers to means that the T/X and receivers are designed/built ground up as 2.4 Ghz systems whereas what you have chosen is a modular system and by changing modules can be alternated between wavebands. The choices are for the consumer "you" to make as indeed it is also as to whehter you go 2.4 in the first place . I like you have gone with Futaba, not being worried about checking to see if I have the right model selected before I switch on and fire up and also liking being able to still use some of my 35Meg stuff

[Tom Doyle]

Thanks Ultymate. So it's a case of maintaining current discipline of checking Tx model memory with actual model before committing aviation. Having said that, I intend to dedicate the Spektrum module to one FF9, will 'model match' still not work?

 Tom

[Ultymate]

No Tom at the moment Futaba do not have "model match" at all at this moment in time whether it will appear later is anyones guess

[Tom Doyle]

Thanks again Ultymate. I think I have got it. So 'model match' is not a function between Spektrum module and Spektrum Rx but a limitation of the Futaba Tx software.

Tom

[Frank Skilbeck]

Tom - when changing back to 35, don't forget to extend the aerial

[Tom Doyle]

Thanks for the reminder Frank. Yes I'm at that age now when it is all too easy to forget things. Hopefully though, with two transmitters, one dedicated to 2.4G and one to 35MGz, it should be less of a problem. Famous last words!

 Tom

[Tim Mackey]

Put simply....model match is ONLY available with a true "from the ground up" purpose designed 2.4Ghz set  - and not with any "modular" set.

[Myron Beaumont]

Timbo 

Occh  I the nou ! Welcome back 'Glad you had a lovely holiday

[Tim Mackey]

Darren Hill wrote (see)

Hi Timbo,

Reassuring tests...

I have a DX7 with AR7000 and AR6200, both of which have more range than my eyes.

My friends with DX6i's have pointed out that the geographical zone can be user set on their TX's. I have a fair amount of experience in long range WiFi applications and equipment purchased from USA is invariably 2 or 3 times more powerful than its european equivalent. They have suggested that if range becomes an issue, try setting the user zone to USA. This could potentially increase the output of the TX. However I have no way of testing this theory. Maybe you could shed some light on this.

Regards

Darren Hill

This link may be interesting... dBm etc

Setting the DX6i Tx to the US output mode is illegal in this country, as the home office have deemed 100mw as the maximum for 2.4Ghz R/C, and the US sets have peak output power levels of anything from the same 100mw right up to 1000 mwatt....depending on who you believe !

Choosing the "illegal" setting will probably also void your insurance cover in the unfortunate event of an accident?

If this helps.. ( and it probably wont ) here is a quote from Paul Beard ( Mr Spektrum )

"European type approval restricts 2.4GHz output power to +20dBm (100mW).

There's less than 3dB difference in the peak output power between EU and US DX systems. However there is only a very minor reduction in range and no impact on selectivity and both versions are classified as full range systems capable of controlling any RC aircraft with plenty of margin.

The 3dB difference is very minor when you consider the total path budget of the systems:

Path = RX sensitivity + RX coding gain + TX power
98 + 18 + 22 = 138dB for the US
98 + 18 + 19 = 135dB for EU versions."

Now of course....3db IS actually a lot of difference really 'cos the db scale is logarithmic,19 dBm is approx 79mW whereas 22dBm is 158 mW so a 3dB rise in Tx output from 19dB to 22dB is a doubling of output power.

Having said all that.... I still recommend the KISS principle whenever possible - The CE approved legal sets sold here for our use are perfectly capable of flying a model aircraft well within the visibility limits of our eyes. The receivers have more to do with sensititvity and satisfactory signal reception than the Tx, and providing you select the correct receiver ( and even the so called park fly 6100s etc have fantastic range ) and install it all correctly and use a suitable power supply....they work fine.

Stay legal, fly fine..... just my 2PW

PS remember that 100m/watt was the output power of our "old" 35Mhz sets too, and I dont remember anyone ever complaining that this was insufficient.

[Tim Mackey]

Thanks Myron...yes very enjoyable and the weather was great on all but one day - loved Scotland - a truly beautiful place.

[Andy Harris]

Yo Thread ...

Just back from a States trip.  I took the DX7 and 6200 + 6000 RXs.

In 12  flights we had 3 major glitches resulting in two unscheduled arrivals.

The first two glitches on the 6200/Brio10 happened in same section of the flying place, the first was recoverable, the second (on the very next circuit) wasn't (was intending to land after the first and so was significantly lower).  I was later told that this area of the flying field was a 'Bermuda triangle' between 5-6 in the afternoon.

The third glitch happened on the 6000/Parkzone T28 directly in front of me on a gentle upwind pass of the runway at about 10m. Rudder and Elevator went to full travel, instant game over.

So my 2.4 experience is now 15 flights, 4 glitches, 3 crashes.

Something is wrong, probably the DX7, so I'll contact Horizon...

Andy