I think I've got interference from a Brisson 3.2 i,ve been running. I just crashed a second plane with this motor due to the futaba pcm reciever going into failsafe or hold. At first i thought it was a power or reciever problem but that was all replaced.

How can I determine if indeed I do have interference from the moter and correct it? I have looked for loose metal to metal contact and found none.

I had a similar problem in a Sukhoi 1/3 scale. I ended up moving all radio related components as far back as possible. Batteries and switches also. I also used an 8 channel FM receiver. My 8 channel PCM seemed more susceptible to ignition noise.

I bought the pcm because fm was really bad. I already put good seperation between battery and servo extensions. Also the Rx ant is seperated. All the ignition hardware is around the fire wall (18" ahead).

Did you do the recommended antannea down range check??? What was the result???

Yes, we did the range check and got to 130' and had no glitching with motor on and off.

On what plane was this with ...?

Size, make , model..

Do you have a metal rod going to the carb? If so then you need to change it and do you have a resistor plug in it? Is your ignition in a metal box?



smallplanes

I had an "interference" problem several years ago with an older Sachs 3.2. Radio check was fine w/o engine running, but everything would go nuts when engine was running. I did everything I could think of, moved equipment, changed plug and linkages, and rerouted antenna. No luck, so I started removing components from the system. As soon as I took the switch out and plugged the battery straight to the receiver, the problem went away. Worn switch was arcing and losing contact with the vibration.
Have also seen a situation where all was fine and when the model was turned on it's side, there was a major glitch. Turned out to be a broken "filter" crystal in the receiver.

Maybe a Bosch cap might help.

First thing to do is do all the checks with a PPM receiver. A PCM rx can hide a potential problem. It's a thought to always set up a gasser with a standard rx and eliminate any notable probelms before installing the pcm for flight. The PCM receiver is there to provide more info to the system and to reject some outside rf, not to mask any pre-existing internal problems.

Next thing to do is to try and determine where the problem is coming from. It can be a long and painstaking process, but you will have to use the arrangement that you had prior to the crash. It will be a one item at a time in a process of elimination, starting with the ignition switch. Then move to each and every servo and extension. Never try two items at the same time.

The throttle rod can be any material you want, as long as you do not have a direct metal to metal contact. Some form of plastic or nylon between the rod ends and any ball links or clevises will do. A simple nylon clevis will break the conductivity chain.

Look for loose nuts and bolts that may be rattleing on a metal surface. Check that you are using a resistor plug. Check the shielding on the plug wire. Check the connectors on the small ignition leads for looseness. Check the condition of the battery wires, etc. There are so many things to check that it can appear intimidating, but it has to be done.

BTW, 130 feet is not really not that good of a range check. With the current crop of computer radios, well over 200 feet is very common.

teletiger, 2 quick things to check. 1. Since it has a rubber boot for the plug, make sure its fitting correctly, very easy to place the boot off to the side slightly and the metal connector will go beside the plug end, not over it tightly. 2. Make sure the braided wire at the plug end of the wire is crimped tightly in its sleeve and screwed down tight to the head. Both of these can give intermittent problems with the radio but the the engine may still run fine.

Ed M.

I've had interference problems caused by defective Futaba receivers(two of them and they were new), and a bad Futaba servo(had been in the plane for a while and probably had vibration damage).
The problems went away when I installed Hitec equipment.

John

The plane is A greatPlanes 1/4 Pattty Wagstaff Extra 300, Futaba pcm Rx & Tx, HiTech digital servos, dual heavy dutty batterieas and switches in parralel, Heavy duty extresions with filters.

All those thing were checked and the throttle linkage is not metal. The range check was fine at 130' and I didn't see the need to go farther, thats all. Anymore suggestions?

A range check is NOT just 130 ft and all is OK. A proper range check is baseed on a percentage between engine running and not running.
All else fails send your ignition to CH for a Bosch cap.

I already sent the ignition to Brisson so they will test it. Do I need to ask for a Bosch cap? I don't know what one is.

I did a range check the other day with the motor running on one of my planes and i only got 135ft with a futaba pcm rx and about 200 ft with the motor off. So i flu it and it was ok no problem's. All you have to get is 100ft thats it,if you get more than that then thats even better. I saw a plane just like the one you have with a fuji 50 on it and it had a good range check, but time they took off with it it went in to failsafe and then went to full throttle and hit the dirt. The guy that had it got another one and he put the same stuff in it the same way it was in the 1st one and he had no problems,it flu great. We had about 5 planes at our field with pcm rx to go down within a months time.All the plane that went down had been flown many times before we're still not sure what happened but there was something in the air.

smallplanes

Yes, ask for a Bosch cap. Its a metal spark plug cap instead of the rubber one. It has the ground wire soldered to the cap itself so it eliminates the loose ground wire that sometimes is a pain to secure properly. I think it's about $20.00.

TKG,

I kinda get a kick out of some of this. The manufacturer of one of the most popular and effective ignition systems on the market world wide comes in and tells a guy the way things really are, and then someone comes in and states that a range check "only has to be 100', that's it"

Absolutely amazing

Pat

Silversurfer

In your post earlier you said check the servo and extensios. This is the only item I'm not sure how to check. Can you elaborate please. They appear to be fine.

Also I have a resistor plug.

Ya can lead a horse to water, but........

Pull the plug and check to see if it's fouled really bad. This has been known to cause a problem now and then. Not very often, but has. Check that the plug is tightly assembled and that the insualtor hasn't been cracked somehow. It could still fire this way, but will radiate.

Are you using any mylar type of tape to hold the antenna down anywhere on your planes? If so, get rid of it. Several times I have seen terrible and so-so range checks become stellar just by removing that type of tape. It's the clear packing type of tape.

Take all your extensions and one by one wiggle them to see if you get any bounces in a servo with the radio turned on. Again, use a standard receiver, not a PCM. Check to see that all the plug ends are clean and tight. Make sure you don't have any wires that have started to pull out of the servos or the connectors. If you can get your hands on one, use a H-9 servo amp and volt meter to check the voltage draws on each servo at neutral and under load. A digital servo going bad will often spike the receiver. Any servo showing a lot higher amp draw than all the others should be suspect.

Do you have any aileron extensions that get plugged and unplugged often? Check them very closely. I lost an Ultimate when two aileron wires shorted out because each time they were plugged in they were cut just a tiny bit on the edge of a nylon wire tie. The result was inevitable, it was just a matter on when.

Now go back and check all the nuts, bolts, cables, etc. to be sure they are tight. If you are using carbon fiber pushrods, ane any of them rubbing together? If so it will be a very bad thing. If the switches are old or have been around in use a long time, replace them. It's cheap insurance. What is the condition of the ignition battery? Is it new and holding a full charge, or is it old and weaker than it used to be?

Get the Bosch cap from CH. It's the best RF insurance for the ignition on the market. I switched to them some time back and they work well. Those that run DA and 3w don't have a choice, their caps have to be ultra good because they can't get a resistor plug. That's one of the reasons for the Bosch style cap on our ignitions.

If you have any other questions, get in touch with TKG. He IS Ch Electronics and ignitions. Bill owns it, but Terry is greatly involved.

Thanks for the tips.I have not used the ppm reciver yet so I give that a try. Most of the rest has been done but I need to get the servo amp and volt meter. Unfortunatly I can't test until I get another plane.

Thanks again.

Well i don't know what brand Radios you guys use? I use futaba and if you would take the time to read a little in the manual you would see that they say all you need is 100 ft. But i guess they don't know what there talking about ether. I have a few gas planes and i know a lot of people that have big gas planes and all we ever try to get is 100ft . I guess theres only 2 or 3 people in the world that knows how to do a range check. I'm sorry if i'm not one of them.


Thanks again
smallplanes

Ya I agree that the manual only states about 100 ft.

I have never had a range check less than 100+Yards though. I usually give up walking much futher than that.

A hundred feet with a glow motor is fine, but I fly my gassers a lot farther away than 100'. Once or twice I even forgot to extend the antenna.

BTW, I fly JR and as a rule I quit with a range check when it looks like I'm going to have to take a break on the walk back because I'm so far away from the plane. I know of many Futaba, JR, and Hitec radio installations that provide an equally long range check, engine running or not. I don't currently know anyone who flys an Airtronics, so I can't say anything about those.

Those that take the time to listen to and heed the directions of the ignition manufacturers usually keep their planes a lot longer than those that don't. But if you really believe that you know more about a product than the guy that manufactures and designs it.......... Like TKG stated, "you can lead a horse to water."