more problems with my spektrum

[crispin church]

Yakmad well must say you mite of hit the nail on the head there it use that type of switch as well will look in to that

well done some one talking sence

[JohnnyB]

Yakmad, not quite sure what you mean here about "a short across the signal and ground wires". How would that occur?

John.

[YakMad]

JohnnyB,

The switches I had problems with caused a slight short accross the negative and signal wire as the switch was being switched on but this was enough to put the receivers into bind mode. I put it down to poor quality materials and bad design. A switch from a battery only needs a positive and negative connection to operate correctly but these heavy duty switches have 3 wires, the signal wire is redundant on a switch but as I found was the cause of my Spectrum receivers going into bind mode, removing the redundant signal wire solved my bind problem completely.

[Cuban8]

Don't forget that Spektrum gear is very fussy about its RF environment at switch on. A system that is otherwise perfectly OK will appear dead during boot up if the required number of good data packets is insufficient. I've seen this over the flying field with my own gear (DX7) when switching on close to a line of cars with their tail gates open. The system just would not connect because of (I suspect) reflections/corruption of the signal due to the very close proximity to large areas of sheet metal. For all the world it looked like a lost bind, but was actually reacting just as the designers intended.

Spektrum have had their problems (DX8 was/is a disaster for them) but just try doing a search for Futaba FASST problems and you'll find pages of alleged lock-outs, faults, etc etc. Much of the time we're our own worst enemy by cutting corners or just bad engineering practice.

 

C8

Edited By kevin goodwin on 09/05/2012 11:16:24

[Miroslav]

Hi all,

I'm a former ATC officer and have had long experience with "rf issues". Even the most sophisticated radio gear can suffer from interference, whether it be from other rf sources, weather etc. Nothing is bullet proof, despite what some rc radio manufacturers will claim.

For my part, my Parkzone Radian glider took off on a solo run in August 2010 (its seared into my memory!) despite the fact that I was in a rural location, on top of a hill, with clear line of sight and no powerlines, radio masts, or cell phone masts etc within a mile of me. I had done my usual range check pre-flight and it passed successfully. I found the Rad after a few hours of searching and discovered that the AR500 rx was flashing. What caused the loss of signal remains a mystery to me and it unfortunately gnaws at me everytime I send a plane up, i.e. every unintended wiggle makes me think "oh no, she's out of control".  The upside is that its made me a safe flyer and I always plan for the worst ,and if the worst happens and she goes out of control, then at least she'll hit the empty patch of ground and not any person, building etc.

My point is that by all means, carry out full pre flights, incl range checks, and you might save yourself a lot of grief but be prepared for the fact that sometimes things go inexplicably wrong and its bye bye plane. Its all part of the hobby.

Edited By David M on 09/05/2012 17:05:57

[Tim Mackey]

Your previous experience and knowledge of "RF Issues" coupled with a proper understanding of the AR500 should have then told you that the "flashing AR500" has nothing at all to do with loss of signal. What you suffered from was a brown out - caused solely by a lack of adequate voltage to the receiver.

As I have stated MANY times in the past, signal loss is not shown on the receiver by flashing lights, and brown outs and signal loss are completely unconnected.

Edited By Tim Mackey on 09/05/2012 17:15:38

[Cuban8]

Posted by Tim Mackey on 09/05/2012 17:14:55:

As I have stated MANY times in the past, signal loss is not shown on the receiver by flashing lights, and brown outs and signal loss are completely unconnected.

Edited By Tim Mackey on 09/05/2012 17:15:38

Spot on!!

C8

[Tim Mackey]

I should apologise...re-reading that post of mine again this morning, it does come across rather abrupt...... albeit factually correct.

Considering thats my first post for quite while, hardly appropriate really

Put it down to my current demeanour

[Pete B]

Nah, Tim, compared to Myron you're still an amateur grumpy - anyway, it shows you're still keen to keep us on the straight and narrow.........good to hear from you!

Pete

[Miroslav]

Posted by Tim Mackey on 09/05/2012 17:14:55:

Your previous experience and knowledge of "RF Issues" coupled with a proper understanding of the AR500 should have then told you that the "flashing AR500" has nothing at all to do with loss of signal. What you suffered from was a brown out - caused solely by a lack of adequate voltage to the receiver.

As I have stated MANY times in the past, signal loss is not shown on the receiver by flashing lights, and brown outs and signal loss are completely unconnected.

Edited By Tim Mackey on 09/05/2012 17:15:38

Hi Tim

You are quite correct that the flashing orange light is caused by a brown out. In my case, this flashing light might have been caused by the Rad's twitching servos continuing to suck juice from the lipo while I spent almost two hours searching for her and thus the rx didn't get sufficient power which resulted in the flashing light.

What caused the Rad to take off on a solo run is the mystery. If 2.4ghz is "bullet proof" as some radio makers would have us believe, why did I lose radio lock with her? My own pet theory is the ar500 rx itself. I had another incident with another ar500 when my Me109 flipped over onto her back and nosed in from two hundred feet up totally destroying the plane. She just wouldn't respond to any control despite my having plenty of time to try and save her. As usual, I had done my range check, there was a fresh battery in the 109 and my telemetry device showed that the voltage was a steady 11v when she went out of control less than 60 seconds into the flight. Since then, I've ditched the ar500's and now use ar600 or orange rxs and have no other problems.

So in three years of rc flying, I've had just two crashes where the common denominator was the ar500 rxs in the two planes. My tuppence worth.

[Olly P]

Posted by crispin church on 07/05/2012 19:04:13:

on our site we had army radio truck with a sat dish on and when any one flew in line with the way the dish was pointing the signal was lost we was within 60 meters

and when none of us flew that side of the airfield there was no probs

Crispin,

 

I expect what you experianced was a swamping of the reciever due to proximity. despite signal seperation the Electronics have to discriminate between what the antenna is feeding in the intended band and what it is actually hearing overall. While antenna lengths are 'tuned' to have the best reception in a certain frequency they can still be swamped by something transmitting on a high power on a spectrally very different frequency. Mobile Sat-com tend towards the top end of power to ensure it punches through the ionosphere and doesn't skip off. If it was a Point to Point system the dish would tend to be less powerful, as you want it to bounce back.

The way I explain this when I have to teach it is this. You are listening for a specific noise, say a note played from a violin. just one note, it's length will tell you what to do. In the middle of nowhere with no other noise this will be easy to hear. now add some distant traffic noise, and you will still be able to hear it, now try in a heavy metal concert......

Signal Swamping is nothing new, and indeed if I was to see a mobile communications site, military, civilian or media related I would politly knock on the door and ask what powers and frequencies they are using before even considering flight, and test for interference before committing aviation. In addition I would ensure if on private land they had all the correct authorisations to be there.

Olly

10 years in military communication......

 

Edited By Olly P on 10/05/2012 16:03:03

[crispin church]

olly P

many thanks

the RAF owns our site and let Army use it and if ok we are then allowed on

so we are very greatful in being allowed on and if they cause us interference then we work round them

we get some great air display at times helis, herks, c17, and para drops

[John Olsen 1]

Olly, The ionosphere is not really an issue in satcoms, the frequencies bands used are chosen because the atmosphere is highly transparent at those particular frequencies. The high powers are used because the path is 22,000 or so miles long so the path loss (due to the inverse square law) is quite high. High gain antennae are also used so that the power is being concentrated in the useful direction, and the one I was involved with thirty years ago had an antennae gain of 60db, with travelling wave tube amplifiers capable of 10kw or so. So the EIRP would be of the order of 10 GigaWatts or so, but of course only in a very narrow beam, about a tenth of a degree or so, and only in the far field. In the near field, which is the only place a model plane would be likely to find itself, the power would to a first approximation be spread over an area roughly the same as the antennae size, but would still be plenty high enough to swamp a receiver, pretty well no matter what it was tuned to. The arrangements used to prevent swamping the systems own receiver are far from trivial! I'm not familiar with the equipment that the military uses, but it is quite possible that they are using higher transmitter power to make up for the limited size of a mobile antennae. (They would also need higher power at the satellite end, which brings its own set of problems.)

But actually, a satellite system like that is pretty low power compared to a terrestrial tropospheric scatter system. These use fixed antennae of similar gain to the satellite one above, and much higher power outputs, 50kW or so has been used. You really don't want to get into the beam of one of these. They were never common, and I am not sure if any are even still in use. They were used where there was no easy way of having a chain of repeaters on land, and were more common before satellites were available.

But the ordinary common or garden terrestrial microwave link is a much more benign sort of beast, with usually no more than 5 Watts or so of power, and often much less. Always intrigues me that the receiving end was effectively detecting something comparable to a torch bulb at a distance of maybe 50 miles or so.

regards

John

[Olly P]

John,

I know. Was trying to keep things simple.

'Scatter' or 'bounce' comms are something of a speciality these days. One I am very familiar with. There are occaisions when these are preferred to Sat-com, and indeed can be more reliable. While the power tends to be somewhat higher, they are also less focussed. I really don't want to go into this one any more on a forum....

Given the description that Crispin gave I think I know what kit he was talking about and it would have been a direct sat link system, probably one of the larger portables. The power on these is actually not much more than those on the fixed systems, mainly because of some very clever engineering on the way they pack away!

You would be surprised how good this kit is now - we have been using it a lot!

[Martin Harris - Moderator]

Posted by kevin goodwin on 09/05/2012 11:14:12: just try doing a search for Futaba FASST problems and you'll find pages of alleged lock-outs, faults, etc etc.

I did, but in fairness they virtually all datet from 2009 and earlier. Is anyone aware of any current common faults affecting either version of Futaba FASST?

I have no axe to grind over FASST although due to a slight error of research, I do have an unused FASST transmitter module which I thought I'd be able to sell on when I bought an "as new" FF10 for my Jeti module to live in!

[Myron Beaumont]

My FASST Rxs have behaved impeccably .Cost (£10 'ish more than others)hasn't come into it 'cos I know they won't let me down unlike certain other brands talked about (guess which?) Would your Tx module fit my Optic 6 (originally 35 Mhz) and be compatible with all my Futaba & Frsky Rxs ? I have the Corona module in it but not really confident to use in a model that's taken many hours to build due to having to rebind a couple of the rxs everynow and then.If it does I will buy it cos I love My Optic . In fact anything made by Hi-Tec .(& Futaba )

[Olly P]

No issues seen here, well, none which where or are believed to be the Rx's fault....

[Martin Harris - Moderator]

Posted by Myron Beaumont on 11/05/2012 16:41:09:

My FASST Rxs have behaved impeccably .Cost (£10 'ish more than others)hasn't come into it 'cos I know they won't let me down unlike certain other brands talked about (guess which?) Would your Tx module fit my Optic 6 (originally 35 Mhz) and be compatible with all my Futaba & Frsky Rxs ? I have the Corona module in it but not really confident to use in a model that's taken many hours to build due to having to rebind a couple of the rxs everynow and then.If it does I will buy it cos I love My Optic . In fact anything made by Hi-Tec .(& Futaba )

Unfortunately it's unique to the FF10 - there's a direct digital input rather than converting from PPM - a set of pins in a projection at the side means that a 35 MHz or other 2.4 GHz module will still fit in the aperture.

Best get back on topic or the mods'll be after us!

Edited By Martin Harris on 11/05/2012 16:56:39

[synapsis]

Hi I'm hoping to find some help here. Here goes...

We had to change our airfiled from one location to a new one, which is even more isolated.

Problem is I have lost 3 planes there from the lose of connection, at first I thought it could be th battery or somethong like that, once my plan did a nose dive orther times it would act up but I was able to bring it down safely, After the second crash I was starting to wonder if there could be an external interference. Toady on take off it started to act up go up and down like it would lose the link for brief moments until it crashed. Now on the first two planes I was using my DX7 but today I was using my DX8 so know I was sure sonething is making me lose my connection. The ohers where not so convined until a friend after flying without problems for 4 minites lost connection and the plane did a nose dive. He was using a Futaba.

My question is what in the world could cause such an interference as there are no powerlines in sight.

All these planes and radios never had problmes until we changed airfields.

I hope someone can give me a heads up what to look for (besides a new airfield ).

 

Thanks

Edited By Steve Watson on 26/05/2012 21:12:54

[Wingman]

Is there a possibility that there could be a buried power cable under the field - bit of a long shot - it would have to be carrying kilovolts to affect 2.4 - you can check using a magnetic compass - if it swings about crazily you've got a problem. Failing that walk about with a receiver and battery and check for loss of lock.

[synapsis]

Thanks Wingman for the reply, I don't nelive there is a power cable as there are fields all around and they have crops.

I will try what the test and see what happens. Today there where no problems and it only happens every once in awhile.

What a pain not knowing when it will happen again or the cause.

[Cuban8]

Posted by synapsis on 27/05/2012 20:23:13:

Thanks Wingman for the reply, I don't nelive there is a power cable as there are fields all around and they have crops.

I will try what the test and see what happens. Today there where no problems and it only happens every once in awhile.

What a pain not knowing when it will happen again or the cause.

Are any other flyers getting these problems?

C8

[Barryorbik]

Is your field near to any military or other active commercial airfields as signal corruption can happen if ground radar is sweeping the area. If the problems continue it might be an idea to contact the home office to get them to do a frequency scan at your flying site to identify any possible interference source.

Barry

[Martin Harris - Moderator]

I wonder if any Spektrum users can assist here?

I was maidening a model for a clubmate today. The owner has a converted Spektrum DX7 transmitter which operates from the left stick with the rudder controlled by a twist knob on the stick and a slider throttle on the left flank. This is due to his only having the use of his left arm.

I was using it with my right hand, holding the transmitter with my left hand and due to the awkwardness involved, asked someone to input some necessary aileron correction. The model had been airborne for a couple of minutes but during this process suddenly dipped its nose from level flight and good airspeed and went into a left banked descending spiral dive (not a spin before anyone suggests this) and failed to respond to any control including the throttle, which remained open. I had time during this to consciously check that I was indeed using the correct stick and had moved the throttle slider to idle!

The model hit trees and the fuselage came down through them relatively undamaged with the receiver still connected. The servos all worked (although the elevator horn had sheared) but there was a red light which flashed a repeating sequence (2 flashes - pause - 2 flashes) and apparently this had not been seen before. A range check seemed OK.

Can anyone interpret these flashes please? I'm fairly sure it was a Spektrum receiver but it didn't have a satellite as far as I recall.

I noticed a rather odd thing afterwards. I had been calling for right aileron trim - but the trim was fully left. The "trimmer" confirmed that he was inputting right trim and had even repositioned himself to ensure he was correctly orientated. Logically, I would say that he was inputting the wrong trim and with the unfamiliar control method (pinch grip, left stick with the right hand and light return springs) I can't confirm either way and it wouldn't have affected the elevator anyway but he was absolutely convinced that he was inputting right trim. The trim responded correctly on test.

One other thing that I can dismiss, although there is a range check button on the back of the transmitter fairly close to where my unconventional grip was holding the transmitter, I'm certain that I hadn't accidentally pressed it - there's a very definite click when you do and the model was quite close when the loss of control started anyway.

Edited By Martin Harris on 12/10/2013 23:20:45

[WolstonFlyer]

Hi Martin

If it is an older DSM2 receiver like an AR500 ( no satellite) the flashing red light means that a power brownout has occurred causing loss of power to the receiver, the light flashes to warn you. Could the flight pack be on its way out or perhaps there was a stalled servo etc ?