Interference problem HELP please
07-16-2012 | 07:33 AM
#1
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From: Mexico city, MEXICO
Interference problem HELP please
Hello everyone.
I´ve been flying with my converted Mitsubishi 33cc for a while experiencing some intereference with the Rx every flight at the same moments. Take off and landings
I´m flying with an FM 72 MHz Futaba 8 channel Receiver
I noticed that every time when I take off, there was a glitch which takes the throtle down and move the ailerons but it was quick and the plane goes on flying OK.
As well every time I came on the final approach and take throtle down the plane glitch specially with the ailerons (doesn´t happen if i do a low pass at full throtle)
I have my Rx and Battteries some 14 inches distance from the magneto
Throtle is instaled with a steel pushrod inside a rigid plastic tube with a plastic ball link to the carb and an EZ connector to the servo
Please give me a hand on what can I do.....I crashed my plane this last weekend managing only to get the landing ripped off and some minor damages.
Thanks everyone.
VÃ*ctor
I´ve been flying with my converted Mitsubishi 33cc for a while experiencing some intereference with the Rx every flight at the same moments. Take off and landings
I´m flying with an FM 72 MHz Futaba 8 channel Receiver
I noticed that every time when I take off, there was a glitch which takes the throtle down and move the ailerons but it was quick and the plane goes on flying OK.
As well every time I came on the final approach and take throtle down the plane glitch specially with the ailerons (doesn´t happen if i do a low pass at full throtle)
I have my Rx and Battteries some 14 inches distance from the magneto
Throtle is instaled with a steel pushrod inside a rigid plastic tube with a plastic ball link to the carb and an EZ connector to the servo
Please give me a hand on what can I do.....I crashed my plane this last weekend managing only to get the landing ripped off and some minor damages.
Thanks everyone.
VÃ*ctor
07-16-2012 | 07:52 AM
#2
Senior Member
RE: Interference problem HELP please
ORIGINAL: oddy
Hello everyone.
I´ve been flying with my converted Mitsubishi 33cc for a while experiencing some intereference with the Rx every flight at the same moments. Take off and landings
I´m flying with an FM 72 MHz Futaba 8 channel Receiver
I noticed that every time when I take off, there was a glitch which takes the throtle down and move the ailerons but it was quick and the plane goes on flying OK.
As well every time I came on the final approach and take throtle down the plane glitch specially with the ailerons (doesn´t happen if i do a low pass at full throtle)
I have my Rx and Battteries some 14 inches distance from the magneto
Throtle is instaled with a steel pushrod inside a rigid plastic tube with a plastic ball link to the carb and an EZ connector to the servo
Please give me a hand on what can I do.....I crashed my plane this last weekend managing only to get the landing ripped off and some minor damages.
Thanks everyone.
VÃ*ctor
Hello everyone.
I´ve been flying with my converted Mitsubishi 33cc for a while experiencing some intereference with the Rx every flight at the same moments. Take off and landings
I´m flying with an FM 72 MHz Futaba 8 channel Receiver
I noticed that every time when I take off, there was a glitch which takes the throtle down and move the ailerons but it was quick and the plane goes on flying OK.
As well every time I came on the final approach and take throtle down the plane glitch specially with the ailerons (doesn´t happen if i do a low pass at full throtle)
I have my Rx and Battteries some 14 inches distance from the magneto
Throtle is instaled with a steel pushrod inside a rigid plastic tube with a plastic ball link to the carb and an EZ connector to the servo
Please give me a hand on what can I do.....I crashed my plane this last weekend managing only to get the landing ripped off and some minor damages.
Thanks everyone.
VÃ*ctor
Try a Sullivan plastic pushrod on your throttle. Even W/a plastic ball link the metal rod could be picking up RF & causing the glitch @ a certain throttle (rod) position. It might be less likely W/EI, but your magneto magnets spinning near the metal push rod might be doing something strange.
As long as you support the outer platic tube near the ends, the Sullivan plastic pusrods are plenty stiff for a throttle application. No chance of conducting RF either.
07-16-2012 | 08:31 AM
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From: Parma Heights,
OH
RE: Interference problem HELP please
There is also a chance that some servo load at T.O. and landing is causing the RX voltage too droop enough to cause a glitch. First, is your receiver battery separate? Do you have a voltage regulator or BEC on it? Do you have some heavy servo load, like a flap linkage that may be binding or a steerable landing gear component?
Electric sailplanes, for example, can have very high servo loads at landing with full flaps. Such loads can cause a glitch if a BEC is used and is not correctly sized for that load.
John
Electric sailplanes, for example, can have very high servo loads at landing with full flaps. Such loads can cause a glitch if a BEC is used and is not correctly sized for that load.
John
07-16-2012 | 08:50 AM
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From: Mexico city, MEXICO
RE: Interference problem HELP please
Thanks a lot.
Actually Yes the Steel Rod when Throtle is down goes near the receiver,
Ill be changing my Rod for a Sullivan plastic one and making some hatches to move receiver and Batteries further back on the plane.
Thank you very much
Actually Yes the Steel Rod when Throtle is down goes near the receiver,
Ill be changing my Rod for a Sullivan plastic one and making some hatches to move receiver and Batteries further back on the plane.
Thank you very much
07-16-2012 | 11:07 AM
#5
Senior Member
RE: Interference problem HELP please
ORIGINAL: oddy
Thanks a lot.
Actually Yes the Steel Rod when Throtle is down goes near the receiver,
Ill be changing my Rod for a Sullivan plastic one and making some hatches to move receiver and Batteries further back on the plane.
Thank you very much
Thanks a lot.
Actually Yes the Steel Rod when Throtle is down goes near the receiver,
Ill be changing my Rod for a Sullivan plastic one and making some hatches to move receiver and Batteries further back on the plane.
Thank you very much
If your RX/batteries are 14" from the ignition & you eliminate the metal RF conductor I don't think you will have any more problems.
1st rule of trouble shooting is to only change 1 variable at a time.
07-16-2012 | 04:37 PM
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From: xnot applicable, AUSTRALIA
RE: Interference problem HELP please
Steel throttle rod would be the first thing I would replace with plastic as mentioned.
Also look for and replace any metal to metal clevices/horns.
Also use a radio noise suppressor spark plug.
Standard plug say for instance ,CM6 , I think the suppressor type is CM6R or CM6RC .
Also look for and replace any metal to metal clevices/horns.
Also use a radio noise suppressor spark plug.
Standard plug say for instance ,CM6 , I think the suppressor type is CM6R or CM6RC .
07-17-2012 | 09:51 AM
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From: Mexico city, MEXICO
RE: Interference problem HELP please
Could anyone post some pics of how to shield the spark plug lead.
I have read of it but i dont quite get how to do it.
Thanks a lot
VÃ*ctor.
I have read of it but i dont quite get how to do it.
Thanks a lot
VÃ*ctor.
07-17-2012 | 10:19 AM
#9
Senior Member
RE: Interference problem HELP please
ORIGINAL: oddy
Could anyone post some pics of how to shield the spark plug lead.
I have read of it but i dont quite get how to do it.
Thanks a lot
VÃ*ctor.
Could anyone post some pics of how to shield the spark plug lead.
I have read of it but i dont quite get how to do it.
Thanks a lot
VÃ*ctor.
Most CDI R/C ignition systems have a shielded spark plug wire/socket. The socket is solid stainless steel & the wire has a briaded S/S cover over the conductor/under the sheath isulator.
Similar in consruction, but different in application to a coaxial cable for your satilite/cable TV leads. 2 condutors, but in the case of the shielded sparkplug lead the outer conductor is a ground.
The braided sheath & spark plug cover ground to the engine via the sparkplug base & also to the ignition module case.
In fact, a good CDI EI system would eliminate your magneto/flywheel, be less prone to RF ineterfearance & save weight overall.
07-17-2012 | 10:29 AM
#10
Senior Member
RE: Interference problem HELP please
Here is a picture of a CDI electronic ignition system for R/C planes.
Note the braided shield on the high voltage plug lead & the metal spark plug socket.
This "grounds" any RF to the engine block/module case.
Note the braided shield on the high voltage plug lead & the metal spark plug socket.
This "grounds" any RF to the engine block/module case.
07-17-2012 | 05:59 PM
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From: moree, AUSTRALIA
RE: Interference problem HELP please
Oddy
All I do is go to a shop that sells commincations equipment ask for some coaxial cable with braided shielding inside it.
You will have to strip the outer layer of covering off the cable to get to the braided shielding.Then I pull the spark plug cap off your lead slip the shielding over your plug lead solder a wire on to the shielding that is earthed to the head of your engine with a small self tapping screw.Make sure the shielding is isolated except for the earth.Then I cover it with some heat shrink.
All I do is go to a shop that sells commincations equipment ask for some coaxial cable with braided shielding inside it.
You will have to strip the outer layer of covering off the cable to get to the braided shielding.Then I pull the spark plug cap off your lead slip the shielding over your plug lead solder a wire on to the shielding that is earthed to the head of your engine with a small self tapping screw.Make sure the shielding is isolated except for the earth.Then I cover it with some heat shrink.
07-17-2012 | 08:06 PM
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From: Salem,
OR
RE: Interference problem HELP please
See if you can find someone installing cable in a house somewhere and just ask for a scrap of the coax cable, I've done that before, I might have just crimped on a ring terminal at one end which should work fine, that stuff doesn't solder very well
07-19-2012 | 04:56 PM
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From: xnot applicable, AUSTRALIA
RE: Interference problem HELP please
Never found it necessary to use shielded cable if the noise suppressor plug was used and eliminate the steel throttle link.
You've kept radio gear isolated best you can so I would try that first.
Shielding would be a final application if all else failed.
TV Co-ax will not be suitable as it is designed for TV signals at very small voltages, maybe just a few millivolts.
Ignition systems operate at thousands of volts and the co-ax does not have a high dielectric strength. i.e. the spark will jump across the insulation to the outer shield under load.
In days gone by, the co-ax cable had a fairly loose shield that could be removed quite easily and re-applied to another cable but these days, co-ax is quad shield and the shield is moulded in the cable and would be impossible to remove as once-upon-a-time.
You've kept radio gear isolated best you can so I would try that first.
Shielding would be a final application if all else failed.
TV Co-ax will not be suitable as it is designed for TV signals at very small voltages, maybe just a few millivolts.
Ignition systems operate at thousands of volts and the co-ax does not have a high dielectric strength. i.e. the spark will jump across the insulation to the outer shield under load.
In days gone by, the co-ax cable had a fairly loose shield that could be removed quite easily and re-applied to another cable but these days, co-ax is quad shield and the shield is moulded in the cable and would be impossible to remove as once-upon-a-time.
