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Ignition question

Old 08-11-2014, 11:14 AM
  #26  
dirtybird
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You people need to pull your head out of the 72mhz sand and get with the 21st century.
RF interference as we knew it is impossible with 2,4ghz .Ignition noise does not have the code to be accepted by the 2.4. receiver. If there is enough noise to wipe out the band the receiver will simply go to fail safe.
I would expect the op has a bad switch,receive,or battery..

Last edited by dirtybird; 08-11-2014 at 11:16 AM.
Old 08-11-2014, 11:22 AM
  #27  
BadAzzMaxx
 
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If you do not believe that it can happen, Install a shielded plug cap on lose, crank the engine with radio on and see what happens and who has there head in the sand.


Have seen it a dozen times cause RF, install the cap right and it goes away.

Milton
Old 08-11-2014, 11:55 AM
  #28  
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I am not saying that the OP has a ignition problem just a possibility.

It could be any of these possibilities

Bad battery connection
Bad battery connection inside the battery
Bad receiver
Lose servo connection.
Bad servo lead, Wire lose in a connector.
Bad switch


Turn the radio on and twist and sake everything in the planes to see it the same problem happens.

Tap lightly on the power switch to check it.

Milton
Old 08-11-2014, 12:54 PM
  #29  
All Day Dan
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Dirtybird, the day you discover an RF device that is immune from RFI, please report it to the Department of Defence. Thanks, Dan.
Old 08-11-2014, 01:01 PM
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Truckracer
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Originally Posted by dirtybird
You people need to pull your head out of the 72mhz sand and get with the 21st century.
RF interference as we knew it is impossible with 2,4ghz .Ignition noise does not have the code to be accepted by the 2.4. receiver. If there is enough noise to wipe out the band the receiver will simply go to fail safe.
I would expect the op has a bad switch,receive,or battery..
dirtybird, we've had this discussion before. You are 100% right, on 2.4 GHz the interference can't be coming in through the RF port but it sure can come into the receiver on the battery and servo leads where it can cause all sorts of problems. In some cases, it can directly affect servo operation. The whole back end of the receiver / decoder / servos certainly operates with very low frequency signals that can easily be affected by spark noise. Our radios are systems and not just 2.4 GHz RF links. As Maxx has said, have seen it happen and is easily corrected when a loose cap is correctly installed. Likewise, on the old non shielded CH caps with separate ground wire .... let that ground wire get loose or break and watch what happens.
Old 08-11-2014, 01:14 PM
  #31  
stevegauth30
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Not to say that it can't be, because anything is possible, but everything is brand new. Rx, bat. Switch, IBEC, servo leads, all but the one throttle servo. For now, I have a crap ton of stuff to look at and check. You guys all had good ideas for me to look at and I will check EVERYTHING. Starting with the plug cap. I will try another switch, battery, and reciever if the plug cap doesn't help. I'm sure with the help of all of you, I'll figure it out. At the least, I learned a lot of what causes this stuff and how to avoid it. I also have a brand new digital servo I'll swap out with the old one on the throttle and probably move it inside the cabin. There's plenty of room. Thanks again.
Old 08-11-2014, 01:49 PM
  #32  
OliverJacob
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Originally Posted by Truckracer
dirtybird, we've had this discussion before. You are 100% right, on 2.4 GHz the interference can't be coming in through the RF port but it sure can come into the receiver on the battery and servo leads where it can cause all sorts of problems. In some cases, it can directly affect servo operation. The whole back end of the receiver / decoder / servos certainly operates with very low frequency signals that can easily be affected by spark noise. Our radios are systems and not just 2.4 GHz RF links. As Maxx has said, have seen it happen and is easily corrected when a loose cap is correctly installed. Likewise, on the old non shielded CH caps with separate ground wire .... let that ground wire get loose or break and watch what happens.

+1

I don't know where the old wife's tale came from that you can not have any rc interference with a 2.4 Ghz receiver. You can very well feed in rf noise through the servo or battery leads. Happens all the time and most gas engine owners come across this problem sooner or later.
Old 08-11-2014, 03:49 PM
  #33  
dirtybird
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Originally Posted by Truckracer
dirtybird, we've had this discussion before. You are 100% right, on 2.4 GHz the interference can't be coming in through the RF port but it sure can come into the receiver on the battery and servo leads where it can cause all sorts of problems. In some cases, it can directly affect servo operation. The whole back end of the receiver / decoder / servos certainly operates with very low freack to the early days quency signals that can easily be affected by spark noise. Our radios are systems and not just 2.4 GHz RF links. As Maxx has said, have seen it happen and is easily corrected when a loose cap is correctly installed. Likewise, on the old non shielded CH caps with separate ground wire .... let that ground wire get loose or break and watch what happens.
Yes we have had this discussion before.Lets go back to the early days RC. Zenoahs were a very popular engine. They were equipped with only a resistor spark plug. There was no shielding of any kind. I flew many A/C with a Zenoah with AM PPM, the most interference suceptable system available.
Yes the servo pulse can be affected by noise, but you must be using damn poor servos if it dont have proper bypass circuits to filter out any noise.
Also the servo pulse circuit is low impedance and will it take a large spike to show up..

Lets go b
Old 08-11-2014, 06:44 PM
  #34  
OliverJacob
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to the op - you can make a simple test to rule out the servo. Disconnect the throttle servo lead from the rx and run the engine with either moving the throttle by hand or a servo tester or separate rx, whatever works for you.
Make sure your radio is on and you'll see if you still get interference. If not - your throttle servo setup is the problem
Old 08-11-2014, 08:29 PM
  #35  
bcchi
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Originally Posted by OliverJacob
+1

I don't know where the old wife's tale came from that you can not have any rc interference with a 2.4 Ghz receiver. You can very well feed in rf noise through the servo or battery leads. Happens all the time and most gas engine owners come across this problem sooner or later.
No I do not know where that Idea came from.But I built a Ign that would eat up any 2.4 system.
We had more RF complaints when 2.4 came out then we were having with 72.Nearly all of these was because they were not getting the plug can on correctly.Or vibration problems in the radio.One customer told me when he stoped the engine the problem went away.So had to be Ign problem.O- Well I do not have to worry about it anymore.The 2.4 system will cover up a lot of errors . They are very good.
BCCHI Grumpy no two.
Old 08-12-2014, 07:17 AM
  #36  
dirtybird
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I got that old wives tail from a simple experiment. I took a cheapie ignition system I got from Hobby King and drove it from a function generator. Then I held the spark plug next to the antenna of my operating 2.4 system. The 2.4 system operated normally without a glitch or going into Failsafe.
The HK system may not be as potent as a C&H system but it made plenty of blue sparks.
I didn't try it next to a servo lead. Maybe i should do that but I wouldn't expect to see any glitches
Old 08-12-2014, 07:49 AM
  #37  
All Day Dan
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All Steve asked was a valid, basic question and he’s getting swamped with everyone’s thoughts. I’ll join in. Dirtybird, that test is not valid. It showed that the ignition did not interfere with the radio for the period of time that you performed the test. That’s not long enough. That spark has the potential of containing frequency components from DC to light. Included in that spectrum is the spread spectrum range 2.4000Gig to 2.4080Gig. It does not happen all the time and that’s the problem. Guys are getting away with it and that’s good. But one of these days it could catch up with you and it has happened at the field I fly at with disastrous results. Like the old saying goes “Don’t ef with mother nature”. Dan.
Old 08-12-2014, 12:44 PM
  #38  
dirtybird
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I performed the test for about 5 minutes. At 50 frames/sec thats 15000 frames. Thats not enough for you?
Please explain to me why you believe interference is accumulative.
Yes the spark contains frequencies from the fundamental all the way up to light and beyond. But none of it has the code the receiver needs to recognize it.To the receiver all it looks like is garbage. The real wonder of spread spectrum transmission is it can look way down into that garbage and find the transmitted data.
Its like if you dropped your keys in a bucket of mud. You can reach down in that bucket and pull out your keys even though there may be lots of rocks in there. You know they do not have the same feel of the keys.
Please take some time to read up on how spread systems work. You might learn something. I am sure Wiki has an explanation of it
Old 08-12-2014, 01:09 PM
  #39  
dirtybird
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Here is a simple explanation taken from Heddy Lamar's biography

During World War II, Antheil and Lamarr discussed the fact that radio-controlled torpedoes, while important in the naval war, could easily be jammed by broadcasting interference at the frequency of the control signal, causing the torpedo to go off course.[SUP][13][/SUP] Lamarr had learned something about torpedoes from Mandl. Antheil and Lamarr developed the idea of using frequency hopping to avoid jamming: using a piano roll to unpredictably change the signal sent between a control center and the torpedo at short bursts within a range of 88 frequencies in the radio-frequency spectrum (there are 88 black and white keys on a piano keyboard). The specific code for the sequence of frequencies would be held identically by the controlling ship and in the torpedo. It would be practically impossible for the enemy to scan and jam all 88 frequencies, as this would require too much power or complexity. The frequency-hopping sequence was controlled by a player-piano mechanism, which Antheil had earlier used to score his Ballet Mécanique.[ci

Last edited by dirtybird; 08-12-2014 at 01:15 PM.
Old 08-12-2014, 02:52 PM
  #40  
OliverJacob
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Hard to prove any of this without extensive tests.
The closer you are to the rx, the less power you will need to jam the signal. But you had to feed in noise over the whole frequency spectrum constantly, which
our ignition systems would hardly be capable of. There is a slight chance, but it's almost impossible.

More likely you will catch some spikes through a servo or battery lead. The root cause might be a faulty shield on the spark plug cap or lead, the result is your servos twich.
I bet you some people don't even know that this is happening. My plane flew fine, the control surfaces would slightly jitter when the engine was running, it looked like this was caused
by the engine vibrations. It would fly fine, once I ran the engine with the canopy off, I notice that the servos moved.

And the servos were Futaba 3251, with a 617 rx, not a high end system, but you'd expect e decent quality here.
Old 08-12-2014, 05:40 PM
  #41  
stevegauth30
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I haven't had a lot of time the last few days, but I did change the throttle servo, set up a different rx, switch, battery, and IBEC. I haven't ran it yet, but hopefully will tomorow. I will report back. If it's still no good, then I'll get new servo extensions and try moving the throttle servo. I also moved the reciever and the telemetry unit way back. There now at least 16 inches away from the ignition. My fingers are crossed.
Old 08-12-2014, 06:11 PM
  #42  
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I accidentally put a non-resistor plug in my 50cc Extra when I was setting it up. While doing the test runups while I was setting the plane up, I noticed some glitching in the servos. When I moved towards the front of the plane, the glitching became severe and in all servos. I found that the metal spark plug cap was not well fitted together and had a gap where the halves joined. I closed the gap and the glitching went away. I of course changed to a resistor spark plug anyway, but the point is the interference happened and it was with an Aurora 9 - 2.4 gig system with all Hitec high dollar servos mounted well away from the ignition.

Bottom line..... it doesn't matter how it does it, but interference from the ignition system CAN affect 2.4 gig systems.

AV8TOR
Old 08-12-2014, 06:18 PM
  #43  
All Day Dan
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Steve, Here’s an image of one of my installs looking from the rear forward.
Servos-Receiver-Switch-Battery-Tank-Ignition. The Optic fiber line for the kill switch is the black line on the right. Dan.
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Old 08-13-2014, 08:34 AM
  #44  
dirtybird
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Here is a test for the unconvinced that anyone can do:
I removed the spark plug and propeller from the Lazy Ace that I just rebuilt. It has an NGH26cc and RXCL ignition.
I then chucked the motor shaft in a hand drill.
I turned on the system and the ignition and put the spark plug in its cap and ran the hand drill.
I pulled the sparking plug back as close as I could to the RX antenna.
The system operated normally.
How long shall I run it Dan?.
BTW that is a nice clean installation in your picture. My only comment is "Look at all of that wasted space"
Old 08-13-2014, 10:42 AM
  #45  
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dirtybird, one more post and I may abandon this subject forever! You can do all the tests you want but real world experience and observation is really the only thing that matters here. Simple fact, there are just too many documented examples of ignition related interference, even with 2.4 radios to ignore that it can happen. The most common being caused by leaving a Rcexl or DA type cap slightly loose where it doesn't make a good ground / shield connection. It happens and that's all I have to say about that.
Old 08-13-2014, 01:25 PM
  #46  
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Well, good news is I found that cause. It was the servo connection for the ignition. With every thing I did, I started it and sure enough it was still doing it. I started giggeling wires and when I got to that one it stopped. So I cut the connector off and crimped on a new one and voila, no more glitching. I really appreciate all the help from you guys. Thanks, Steve.
Old 08-13-2014, 02:55 PM
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Glad you found it. Don't you just love it when you solve a nagging problem??

Reminds me of the time I had just landed one of my gasser planes after a good flight. It was sitting on the runway idling, and I thought "What the hell, I'm going to do a few more touch and go landings." I applied throttle, and nothing happened!! Then I wiggled all the controls and none of them moved either! I went to the plane and removed the hatch, with it still sitting there running, but with me restraining the plane. I touched the battery connector for the receiver, and everything started working, I touched it again and they all quit once again. It was a bad battery connector, but imagine my emotions at that moment about how close I really came to completely losing the plane!

In modern day automotive mechanic's parlance, the "wiggle test" is a phrase that is actually found in the manuals.

AV8TOR
Old 08-13-2014, 03:46 PM
  #48  
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Exactly. Something so minor could destroy years of hard work. I ran it for about 15 minutes and didn't see one twitch, so as long as it doesn't come back on maiden day I'll be good to go. Let's hope.
Old 08-14-2014, 08:50 AM
  #49  
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Let us know how it goes. Pictures and/or videos are always fun too....

Good luck,
AV8TOR
Old 08-14-2014, 09:44 AM
  #50  
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Will do. Thanks again for the help.

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