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RF interference with magneto gasser

Old 03-22-2005, 06:00 PM
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AnthonyH
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Default RF interference with magneto gasser

I have a converted Stihl that was working great and now is causing RF interference. I flew the plane for two weeks and then it started causing interference. I have put in a new RX and crystal, tried different TX on same channel, replaced magneto with one off another engine. I have no metal to metal connections. I removed the switch to be sure it was not the cause. I use nyrod throttle pushrod. All electronics are at least 12" from firewall. I get about 25' with antenna collapsed and then servos start jumping. I have exhausted what I know to do. My next step would be to get a braided tube to go over the spark plug wire. I would have tried that already, but I cannot find any. I would really like to know why the problem started though. Any suggestions?
Old 03-22-2005, 06:25 PM
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smallplanes
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Default RE: RF interference with magneto gasser

Are you using a resistor plug? Make sure your ant. is not running tru any servo wires. Move your ant. around and see if that helps. I had a plane like that and i moved the ant. and it worked a lot farther out.


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Old 03-22-2005, 06:56 PM
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Default RE: RF interference with magneto gasser

put in a new ngk plug if that doesn't do it it may be the transmiter ' I had that problem after flying for a couple years without a problem inded up being the transmitter from range checking with the antenna all the way down . Futaba says to leave one section of it raised .
Old 03-24-2005, 12:40 AM
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AnthonyH
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Default RE: RF interference with magneto gasser

I am not using a resistor plug, just the one that came in it. I have tried two different receivers, both Hitec, and routed the antenna several different ways. Going straight out the top and straight up gives a little better range, but a plane with a two foot whip antenna is not what I want. I have also tried two different transmitters, both Futaba and Hitec, with same results. I finally got some braided tube and covered the plug wire and cap. Bingo! I can now get about 110 ft without servos jumping. I might try the NGK plug to see what it does. Is it a resistor plug?
Old 03-24-2005, 01:12 AM
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Default RE: RF interference with magneto gasser

Hey anthony you definitely need to use a resistor type plug!!! it sure makes a lot of a difference I am almost 100% sure that's your problem. Try it and let me know if there was a difference. good luck.
Old 03-24-2005, 02:02 AM
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Default RE: RF interference with magneto gasser

I might try the NGK plug to see what it does. Is it a resistor plug?
NO. But this will get you head in right direction for knowing what to look for. You owe it to your plane to get a resistor type plug.

http://www.clubplug.net/index.html?h...t/ngk_sym.html
Old 03-24-2005, 10:13 AM
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Default RE: RF interference with magneto gasser

Definately use a resistor plug, on your Stihl you can use a Bosch wsr6f (best plug) or Champion rcj6y, don't use a cj8 bc the electrode is not long enough. Have you ever been in someones car and everytime the apply the gas you can hear it in the radio? They are not using resistor spark plugs. Another thing you might do is replace the plug boot with a "fireproof" boot. Another means to isolate interferance. Try a lawnmower shop.
Old 03-24-2005, 10:31 PM
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Default RE: RF interference with magneto gasser

Definitely try a resistor plug, they usually are a big help in eliminating or reducing interference.
Old 03-25-2005, 04:50 AM
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AnthonyH
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Default RE: RF interference with magneto gasser

I checked the plug and it was a NGK BPM7Y. I checked some of my other engines and found a NGK BPMR7A. I will give it a try. The plug in my Ryobi is a Champion RDJ7Y. Is it a resistor plug? I am going to buy some new plugs and want to go ahead and replace all of my plugs with resistor plugs. What are the best plugs to get?
Old 03-25-2005, 10:49 AM
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Default RE: RF interference with magneto gasser

Most of the time the R in the plug part number means resistor bpmR7a, Rcj7y, wsR6f....
Old 03-25-2005, 12:22 PM
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Default RE: RF interference with magneto gasser

Any Plug with an "R" at the beginning of the part number denotes that it is a "resistor" type plug.... Searched all small engine shops in Atlanta area, none available....A local hobby shop did have 2 champion RJY something that I put in my Homie chainsaw engine, and had absolutely no interferance....Before, I went as far as aluminum taping every single wire in the airframe (except the receiver wire of course) to include the plug wire all the way up to the boot, in an effort to get rid of my interferance....the "R" plug (and grounding the coil) fixxed it.....
Old 03-27-2005, 03:17 PM
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Default RE: RF interference with magneto gasser

The NGK BPMR7A did the trick. I bought two more for my other conversions. I left the braided tube on the plug wire for added protection and looks.
Old 03-27-2005, 11:01 PM
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Default RE: RF interference with magneto gasser

Just for kicks & giggles, where did you get the braided tube? I've got a big pink clone in process, & would like to cover the spark plug lead on the Homie I'm planning on using for it.
Old 03-28-2005, 12:51 AM
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AnthonyH
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Default RE: RF interference with magneto gasser

My neighbor. He is an A&P IA at a FBO. He got me two sizes. They use it for ground straps. I looked at Radio Shack and Home Depot and neither had it. I am not sure where you could get it. Maybe try your local FBO.
Old 03-28-2005, 08:35 AM
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Default RE: RF interference with magneto gasser

I have used the braided shield that I remove from coaxial cable. RG8/U is the type of cable that I get it from. If you know any amateur radio operators they could probably supply you with a piece. Most industrial electronics stores have it. You very carefully peel off the outer plastic sheath, then slip the braid off of the inner insulated wire.

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Old 03-28-2005, 11:31 AM
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mikenlapaz
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Default RE: RF interference with magneto gasser

Visit New England Wire site, they have a pfd on all types of braided shield material. The tinned copper looked good to me.
Now if someone could share how to properly remove/install the plug wire from coil or remove/reinstall the plug boot caps it would be a big assist. (I ruined one coil trying to get the plug wire out thinking it was threaded and it appeared to have been soder).

They also list much smaller diameter braided tinned flat braid that seems like a good material for battery connections in pack construction.

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