I have a friend that purchased a Fuji 24 with the magneto system. He has a Futaba radio and the reciever is more than a foot away but still the reciever seems to get alot of interference. The servo's are going crazy when he doe's a rang check. He said he changed the reciever and the batteries but no change. Has anyone have any fix for this. Possibly a RF filter.

is the engine running a resistor plug? Should be!
Make sure the HT wires are shielded and grounded right from the box to plug.
Make sure your earth return is secure.

Just a couple to get you started.

Have you been to the gas engine forum. There is currently a thread running there about a larger Fuji engine causing interference. Maybe some of the info will apply to your installation.

http://www.rcuniverse.com/forum/m_7117353/tm.htm

Do a search on that forum also, this has been discussed many times and there should be plenty of info and help there.

What type of reciever do you have?

AM and FM will get hit all day and night, no matter what you do.
PCM will not.
spectrum/fasst (2.4 ghz) not sure if they will or not.

did that help?

I run strictly FM with all gas engines.....rarely, if ever get a hit. The PCM is just a disguise.

Dont have any experience with Fuji's, but I did have a similar problem with a 1/4 scale AC I was flying. The solution was to twist the wiring that ran out to the aileron servos through the wings (this was the longest lead run),as well as then wrapping them with aluminum foil as a shielding. Then, run a wire from the engine block as a ground and attach it to the outer foil shielding. This should block a considerable amount of the interference that is coming in to those long lead runs, and was causing them to act basically as antenna's, picking up whatever interference they could. If you have other long leads running out to servos in the Fuse or Wing, I suggest the same thing. I don't fly PCM, and this worked fine. Hope it helps.

ZZ.

PS. Resistor plug is a must too!

I have the same engine and the same problem. I tried most of the cures mentioned in
both threads, nothing helped. I sent the engine to hobby services and the said they could
find nothing wrong, but they would replace the coil because there could be a microscopic
hole in it. I now have the engine reinstalled in my 1/4 cub I have performed a long ground
test with the engine running at different throttle settings with no interference. I am waiting
for a calm day to fly,it has very windy here at present. Hope this helps

I have a 71" CMP Spitfire that gave me fits when I first converted over to gas. I exhausted the interference info at the gas engine forums and tried it all. Then one day while running the engine and scratching my head I walked around the Spitfire and just started laying my hand on everything that even slightly vibrated. (About the entire plane running gassers).
When I got to the tailwheel I grabbed it and the glitching stopped. Long story short,,,,,, metal hubbed tailwheel vibrating against it's axle causing RF noise. Switched to a plastic hubbed tailwheel and all has been fine since. "Just another thing to check in your search."[:-]

My experience is back from the day’s when I worked in a garage and new cars came with AM only radios. If they (the radio) picked up noise one of the fixes we tried was to pull the wires out of the boots slice a quarter in off then reinsert the end brad or tack. With model airplanes and gassers I usually mount the servo right next to the engine (about 40hr of air time with this configuration). I have not had this problem yet but back in the 80’s with G38’s and G62’s (other peoples engines) that were causing this same problem I pulled the wire out of the coil socket, the butterfly and brad stayed in the coil socket. After fishing the butterfly and brad out of the coil, I cut a ¼ in off the wire with a razor. Held the butterfly over the wire and reinserted the brad, it will go in most of the way with thumb pressure (then I used the flat surface of a screw driver to insure it was in all the way). Pushed the wire back in to the coil socket and the two cases where they let me do this it solved the problem. These leads are pretty short now and to do this may require replacement. Twenty + years have elapsed since so they may have found a better interface. I would first look to see if the manufacturer sells just the plug pig tail if they do that tells me it is removable, I’ld order one then pull the old one perform the change and see how it works. If no better try the new one.

The carbon fiber in the spark plug wire has the same texture as the taffy in a heath bar (it has been along time since I had a heath bar). The brad only goes into it fore about 1/8 in and if it cracks around the brad there is the cause of your RF. It is also possible for the wire to break any where in its length if exposed to the right vibration or stress. Or most likely the wire was pulled partially off the brad either in the coil or plug boot (I find the plug boot much harder to re-assemble). If trimming the coil end does not fix it I consider it scrap and get a new wire. Most small engine repair shops will have generic ones.

That is my stab in the dark
Joe

I had this problem with my G38. The problem ended up being my plug cap. I replaced it with one from c and h ignition and it solved it . The little spring inside the cap did not engage well and was arching I believe.
Solve your glitch with FM before switching to PCM. You can do it just keep trying. I was very frustrated over this but in the end it was worth it as I have no glitches with my airplane now.

I had a problem with the Fuji 24 interferring with the receiver that Alex 51 was talking about. I have fixed the problem. New plug, cap, changed receiver to PCM, and battery cable end. Range checked fine at 250 feet. Thanks to all who helped me figure this out with your replies.

Hi Sturtz, I've also converted my CMP spit to a gas and am seeing pleanty of interference. I'm attributing most of it to the proximity of the elevator and rudder servos to the ignition system, you didn't happen to change their location did you? If you did, would you mind posting some pictures of your components layout.

Thanks

Well I dont have this problem yet but was planning on my layout of a CMPFW190 with the servos as far forward as possible and a G26Ei, am I asking for trouble because I need the all weight as forward as possible for CG and I hate adding dead weight

SPEKTRUM

I'm sorry to say that Spectrum is not the "save all". I currently have a similar problem with my ailerons when I am running my Brisson 5.8. I have the JR9303 with spectrum AR9000 reciever. The problem is not through the Rx, but rather through the servo lead itself. My data log on my AR9000 shows very little frame loss and no fades but my ailerons are dancing like crazy. There are only two ways to approach it....try to kill the source of the RF noise or try to shield the aileron leads. Buying a spectrum system will not fix it.

I spoke to someone today that has many years of experience in this area , many of things I will tell you that he said have been stated but he said ,
1)medal to medal
2)EI module not grounded properly
3)EI battery not insulated
4)Engine switch not properly installed or not buffered enought with some sort of anti vibration gromet
5)medal servo screws hitting medal servo keepers that run thru the rubber grumet
I know a lot of this sounds like overkill but I aked him for every known cause , basiclly and simply put he said medal to medal is the most common and in the least expected places
6)engine standoffs

There are lots of suggestions out there on RCU when it comes to solving RF problems. But at the end of the day, you can appreciate that "giving an aspirin for a chest pain" approach will not work for all scenarios. I approach this problem systematically:
1) Determine which servo(s) is making noise and what type of noise. If it's a servo at the end of a long extension lead and it's fibrillations, not RF hit, then it's your digital servos trying to find center and fighting because of long leads causing voltage drop. Solution: thicker gauge extensions and bigger power supply with voltage regulator.
2) Separation of electronics from engine/ignition. I do notice that PCM signal will not solve chatter caused by having close proximity. I try to keep them a foot away if possible and no metal to metal contact on throttle pushrod.=
3) When all else fails, PCM receiver does make a difference. I have a BCMA 40cc in Goldberg 330s that uses a spark plug that came with the motor. This bird had rudder RF chatter all day long until I switched to PCM receiver and flown it over 50 flights now with no problems. All the RF suppression methods that have been suggested on RCU did not help one bit. They include wrapping ignition in foil, ferrite RF chokes, soldering capacitor on the long extensions, twisting servo wires into pigtails, moving antenna outside of fuselage. It may very well be the spark plug in this case, but this was the plug that came with the engine!!

If only your ailerons are dancing and you have a solid link I'd be very surpised if you don't have a vibration issue. Most likely look at the aileron servos extension's plugs for poor contact or corrosion on the plug or plugs. I've seen that to be the cause on 72 Mhz systems as well. Please report back as I want to know that the 2.4 system is allowing your problem Mitch.