2.4 GHz dead zones

[Ajohnw]

From memory going way back getting theoretic radiation patterns out of a simple monopole vertical aerial involves radiating metal ground rods or mesh a long way out in all directions from the aerial to give an effective ground plane. The wavelength is rather long at 35mhz so classical theory doesn't really apply especially to an aerial sticking out of a transmitter. A simple T type dipole helps get round this sort of thing. One half of the top of the T forms a sort of reference for the other with a low resistance feed point in the middle - just what's usually wanted for efficient radiation. My understanding is that theoretical performance is more likely in the microwave regions as the wave length is so much shorter. Be interesting to measure the field strength around a transmitter.

 

The "Spektrum effect"  may have another aspect. Are these incidents more prevalent than they were on 2.4gigs earlier days when there  was presumably only really those about. Implying that things have got worse as more futabas have appeared. I'm basically a design engineer who finished up working on automotive software for rather a long time often sorting things out. Brown outs to me usually mean software bugs or inadequate processing of incoming information. More often bugs. Bugs sometimes turn out as features - wow I didn't know it did that - isn't that great or at least the bug can now be added to the user instructions or features list. This area is basically why I feel there aught to be some standardisation of the basic mechanisms used by the different manufacturers. This doesn't have any bearing on what information is sent by the transmitter only on just how it should go about doing it. There are many such standards about in other areas and we could all be a bit more confident if this area had one too.

 

John

 

 

[Graham King]

Reading this thread, I'm glad I stuck to 35MHz!  With almost no one else on 35MHz in our club, my son and I both use FF9 transmitters with PCM receivers and fly a 3 electric models , 14 glow powered planes from 36 size 2 stroke to 180FS and a Raptor 50 and a Trex 600 (glow) with NO problems whatsoever.

 

The only time we have had "glitch" problems was with a Trex 450  and also the even smaller 250 where the electrics are all jammed into a small space.   Solution?  Cheap Corona module and 2.4 receiver for these two, leaving everything else on the good old, dependable 35MHz.  

 

35MHz is still prefectly useable, perhaps even more so now that everyone else has stopped using it.  Fly till almost out of sight, so no range problems.      I just worry that manufacturers will stop making and selling receivers at some time due to the demand dropping ( or rising for 2.4GHz) .    In fact, looking at pictures in RCM&E, many planes are still being flown -    including review models  and show pilots- on 35MHz (trailing aerials clearly visible)

 

I notice buyers of either Futaba or Spektrum equipment and very quick to defend their choice of purchase - and it seems from this thread that the problem being discussed is confined to just Spektrum.   To date, I have not heard of a single problem with Futaba 2.4.   JR, I believe, use Spektrum technology  (?)  - do they suffer the same problems?  If so , again, I have not heard anyone say so.     In which case it is not the technology at fault, but just one manufacturer with a quality control problem , perhaps?

 

One last point:  A number of people in our club have suffered from the short aerials breaking where they enter the receiver case ( Spektrum receivers)  Is this the reason for sudden loss of control?  Dry solder joint or wire breaking internally ? These littles short wires should be properly supported and not left "flapping" in the breeze.

 

 

 

[Ajohnw]

Not sure if I would support 2.4 aerials as it may well cause problems.

 

Microwaves can be curious things.

 

Watching the news tonight a problem with Apples latest i phone was mentioned. It seems that some people held these in a way that Apple didn't think they would and the result was no reception. The cure seems to be a thin clip on frame that quote " allows the phone to adapt to the user".

 

Another odd one.  Use your cars keyfob and see how far away from the car it will work. When out of range, point it at and touch it to the middle side of your head, look at the car and press the button.  You may well find it will work like that at even at 3 or 4 times the normal range which is subject to general conditions any way. Seems a head can capture the signal concentrate it and maybe beam it out of our eyeballs. No doubt there is some other explanation. Who knows but it works on all of the cars I have owned even the newer ones that use short range fobs.

 

John

Edited By Ajohnw on 07/08/2010 21:47:45

[Chris Bott - Moderator]

Just to redress the balance slightly I must report that our club is dominated by Futaba 2.4. There are also quite a few Assan users. Both have reported problems. From momentary glitches, through 2 second losses of control, to full lockouts resulting in loss of models.

 

However at the same time, radio problems generally have declined as the take up of 2.4 has increased.

[Peter Beeney]

   Chris,
          Your revelations have certainly put a rather different complexion on this issue. It’s the first time that I’ve seen any reported problems with 2.4 other than Spektrum, although I guess I haven’t specifically searched, it’s only what I observe on the strip and read on the forums etc. My colleague is a bit more diligent though, he has researched the subject more thoroughly. Up until now he has found very little evidence of any Futaba or Assan incidents, I believe, so I’m sure he will be very interested in your report.
   With the greatest respect, please, and this only intended a statement of fact, but I do have some difficulty in equating the rising loss of models with declining radio problems. At our strip we have the occasional 2.4 problem, sometimes resulting in a total loss. But not on 35; sure, there are and have been incidents, such as batteries, the very rare duffy crystal, and, of course, the inevitable pilot error. But these are all resolvable, and can be explained. And, with the exception of the crystal, all applicable to 2.4 also. With sensible precautions most of these incidents are largely preventable. Not so 2.4, it would appear these ‘loss of control’ occurrences, nay, disasters, are random and unpredictable, and so far I don’t think anyone has satisfactorily explained what is happening here. For me, the implications are really not very good. I’m sure we must be approaching a point where someone is going to notice. Is there any indication at all at your club as to the regularity of these ‘outages’, of all descriptions, in relation to the number of actual radios?
Maybe, though, overall this not such a big problem. Certainly it seems as though some folks are not affected. It’s difficult to get a clear picture.

   I’m still tempted to convert my MPX to 2.4, maybe I should now take a really good look at this and try and find out how dependable this is. Although I’m not sure that Multiplex, if it behaves as it has done in the past, will be selling anything that is less than one hundred percent reliable. The same reasoning may well apply to Futaba too, but on the other hand, if they are going to accept that their radios are going to cause crashes then that does not bode well for the future.

   Let’s hope it’s not all that bad.                PB

[Biggles' Elder Brother - Moderator]

Peter,

 

I think you are extrapolating an awful lot from what Chris actually said. I'm sure Chris is a "big boy" and can stand up for himself, but I would just like to quote the final sentence of his post...

 

"However at the same time, radio problems generally have declined as the take up of 2.4 has increased."

 

In the presence of that statement its a little hard to see how you reach some of the conclusions you do from his post.

 

BEB

[Peter Beeney]

   BEB,
       Thanks for the reply. I’m sure you are quite right and I’ve got it a bit wrong again. I’ve no wish to try and contradict what anyone says, at any time, it’s just simply that I personally have trouble sometimes comparing what I see with what I read elsewhere. But I think that’s just me; I’m a great believer in trying to prove things for myself if possible.
   I was a little bit peeved when recently I managed to completely splinter someone else’s model because of a radio failure, an occurrence which I think I’ve already described, although the owner wasn’t at all fazed. It probably made made me a little bit averse to 2.4 at the time, maybe somewhat unfairly.
   I’m not sure that in fact that I actually drew many conclusions from Chris’s post, if I gave that impression then I can only apologise; and I did try and qualify my remarks at the time by suggesting that this might not be a big problem anyway. Although from recent experience for anyone that’s had such a little mishap it certainly grabs your attention for a while.

   May I say again, please, that my post was intended by me to be a statement of the facts as I saw them, and not any sort of criticism or disapproval of any other posts.      PB

[David Turner 5]

No need to eat humble pie, just because you may have come to the wrong conclusions.

 

 

What you should say is, "I knew that.   I was only testing you." 

 

 

 

 

Edited By David Turner 5 on 09/08/2010 18:18:59

Edited By David Turner 5 on 09/08/2010 18:19:52

[Chris Bott - Moderator]

Hi all, I did mean that things have improved for us with 2.4

 

We used to have an intermittent glitching issue with 35Mhz. So much so that my flying confidence took a huge knocking. Most flight just waiting for the odd glitch and flying higher than usual just in case, rather than enjoying anything.

 

We tried many receiver types and decided Multiplex IPD gave us the least issues.

When 2.4 came along I wasn´t an early adopter but have ended up on Spekky ´cos of the 2 for 1 Rx offer a while back. Now I´m more than happy and my flying is just about back to where it was a couple of years ago.

[TonyS]

Well chaps,

I feel that this has to be added to the mix....

On advice from one of the blog contributors (Timbo I think) I returned my Tx to Horizon Hobby for a check. It was posted last Wednesday (recorded delivery of course). I checked online and it was delivered on Thursday. On Friday (yes, the very next day) I received it back at home with a note stating that it was checked, a fault had been found on the RF board, this had been repaired and the Tx re-programmed and tested.

I'll be honest, my first reaction was - impossible - they've just banged it in a return bag on the assumption that the problems were pilot error. Then I realised just how cynical I'd become and checked myself. Had it taken three weeks I'd have complained of slow service, 24 hours and I don't believe they've done anything - can't win can they...

So.... I'd like to put on record my gratitude To Horizon Hobby for the fastest customer service repair I've ever come across without exception.

I'd also like to thank them for proving me right - there was a fault - and hence restoring my confidence in the Tx AND, more importantly, my flying .

I have tested it  - first time out was an extreme test - Funjet with the Funjet Ultra Power Set!!!

I will just add a little footnote. As I was flying the plane the motor cut out and my heart sank - I really believed that I was back at square one but, unusually I had control and glided it in without drama, then i realised in my eagerness to get out I'd picked up a partially discharged battery - OOOOPS !! 

[Chris Bott - Moderator]

Hi Tony 

 

That really is fantastic service isn't it!

Well done Horizon.

 

 

[TonyS]

Chris you are quite right.

Any supplier that can turn around repairs that quickly deserves business and I for one would far rather buy a product supported by fantastic after care than one purporting to be perfect. If only I'd sent it back after the first problem !!!

T 

[Tim Mackey]

Yep, great result all round really

[GONZO]

Well I guess I'll find out next week how good HH are. After going through my collection (4 - 2 new and 2 S/H) of AR9000 rx's I find that neither of the new ones (purchased from a large multi outlet UK retailer) exhibit  'Quick Connect' and 'Brown Ou't detection. Additionally, they are slow to lock onto the TX signal on initial switch on and one shows a repeated tendancy to lock out permanently when doing the power interuption to test for 'QC' and 'BD'.  But, the two additional satalite units bought at the same time for the new rx's do 'QC' and 'BD'! One of the S/H units with two satalites looks OK (but needs new aerials), but, the other with one satalite is slow to lock on to Tx on initial switch on and has no 'QC' and 'BD'. A thought, could the incorrect opperation of 'QC' and 'BD' on some peoples rx's be giveing/ accentuating the 'dead zone' effect. Anyhow, tomorrow will see me on the phone to HH.

[Tim Mackey]

I doubt phoning will be of much use - they will likely just tell you to post the lot off to them and then they can do whatever work is required to ensure they are up to speed.

A receiver which is slow to lock on after initial switch on is not really a concern...several of my smaller older Rx units do this - ( although I have ensured that the latest QC firmware is installed) . Once the two units have found and locked each other - its irrelevant and I often wait for up to 10 seconds before they talk to each other.......

[Former Member]

[This posting has been removed]

[Chris Bott - Moderator]

I did wonder if they had been able to fix it so quick because it was a "stock" fault?

 

On the other hand, were they able to fix it so quick 'cos they have so few coming back??

 

I'd love to know the percentage of all transmitters that they are having to fix. I'd expect it to be pretty small, especially for something so safety critical.

 

 

 

 

[GONZO]

This fault in the RF board, is it physical or software? No amount of vigorous tapping or flexing varies the results. They were assembled by the manufacturer, not me. I have my own extensive stock of 60/40 cored solder - obtained when I was last at work, 14 years ago. Plus I have a small stock of the silver rich solder that was used in the repair of the old Techtronics scopes (545 etc). This has just made me think that the effect of the environmentalists on reliabilty (lead free solder) could do with being commented on in another thread.

[Ian Skeldon 1]

Hey Tony that's a great result for you and very reassuring for all owners of Spektrum radio sets, as I said earlier, I have not had any problems with my Spektrum, and hopefully won't, but it is good to see such excellent service. WELL DONE SPEKTRUM

 

Ian

[Ajohnw]

Having spent many years working in an electronics automotive factory I can assure you all that there is nothing wrong with lead free solder.  All down to process control or lack of it if things go wrong. There may be a bit of a problem with hand soldering due to the absence of flux. At home that can easily be fixed with a flux pen. If any one does their own repairs it's well worth having one of those anyway even if there is still some multi core lying about. People who hand solder with it all day usually use a rather hot iron say weller 8 or 9.

 

I've used this thread to comment because it relates to  several comments about having it fixed by the distributors and the wonderful turn around. These days they may have done anything to it and may well have just updated the software. If they are sensible manufacturers it should be possible to do that at home. One aspect of software has changed dramatically over recent years. Microprocessors that are cheap and can be programmed easily usually after the circuit boards have been built. This tends to make companies more relaxed in the testing and proving areas as they know that the software can easily be changed by simply re programming the unit what ever it is.

 

John

 

 

[GONZO]

Clarification required:-

1/ Can lead free solder joints be successfuly resoldered using flux cored 60/40 solder??

2/ Does the flux have to be removed to avoid problems with 2.4gHz RF (eg replacing Spektrum aerials)??

[Myron Beaumont]

Gonzo

Good question . I'm using French " proper "solder and their flux . It seems to mix with heavy duty stuff ie U/c's etc but I wouldn't mix it on electronic components .I read somewhere that it is incompatible ,so I would not mix them .I'd rather clean up the surfaces & start afresh so to speak .

PS   How come I can get proper solder from France when I can't buy it here (I'm thinking of Maplins ) EU comes to mind ,& the regs we & only us abide by.

Don't mention fishing !

[John Privett]

Posted by Myron Beaumont on 16/08/2010 11:52:15:.

PS   How come I can get proper solder from France when I can't buy it here (I'm thinking of Maplins ) EU comes to mind ,& the regs we & only us abide by.

Don't mention fishing !

 

Are you sure you can't get it over here - maybe not from Maplins, but elsewhere?  I'm one of the many who "panic-bought" enough traditional solder to hopefully last a lifetime when the lead-free stuff was about to be mandated.  I've subsequently been told that there is no ban on production/sale of leaded solder - just on the use of it in manufacturing.  So it should be possible to still buy the old stuff...

[Martin Harris - Moderator]

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[Erfolg]

I have also read, that lead free solder will not make a long term joint, in the presence of lead tin solder. Like many of these articles, i cannot remember where and when.

 

From what I remember, the difference in the two compounds form  a chemistry which eventually precipitates to form an effectively dry joint.

 

I have read more than one comment that the difficulty effects a lot of trades, plumbers need to use a high temperature gas mixture to ensure the joint wets properly,. The temperature being high enough to increase risks of fire, poor joints etc. Electronic assembly becomes more difficult in potential or actual damage to components.

 

To the zealots of these measures, all  totally acceptable. Those who disagree need to be subjected to a witch hunt or derided for their lack of knowledge.