Radio interference
 

Hi everyone,

I was hoping to get some help on radio interference !!!

I have a JR2610 with R700 FM receiver and ES539 servos in a PA Bad Boy V2 profile. The radio, receiver and servos came out of another plane which was running perfectly before the swap over. When I did the changeover though, I replaced the standard JR switch harness that comes with the radio to a Hitec heavy duty switch harness.

When I try to do a range check with everything fully installed, antenna down, I don't get anymore than 6ft away before the servos start twitching. It's not just one servo but all of them that start to chatter.

I have installed the switch fairly close to the receiver, would that cause interference? Apart from that I can't think of anything else that could be a contributing factor.

Thanks, FJ

RE: Radio interference
 

There are any number of things that can cause problems as you mentioned. First of all, did this plane have a radio system in it before and if it did, how did it perform? From what I read, you took this known good radio receiver and servo's from another location and put it in the plane. Fine.

Where is your antenna located? Is it fully stretched out? Is it going straight back to the rear? Is it inside or outside the fuselage? What kind of pushrods are you using for the rudder and elevator? Is you RX battery fully charged? Do you have any metal-to-metal connections (most likely for that is the engine throttle clevis).

Did you try to work the RX outside the plane before putting it in? That could tell you if the RX went bad for some reason during the swap out.. maybe the crystal came loose???

Re-check everything about your installation.

To itereate what I asked above, running the antenna inside the fuselage is not a bad thing, but if you run it inside along side metal pushrods, then that can offer a reason for some level of inteference or signal reception degradation.

Check things out as I mentioned above and see if any of the questions are YES. Try to eliminate any metal-to-metal connections that are associated with the throttle. Vibration causes severe problems when there are metal-to-metal connections like that.

Best of luck.

DS.

RE: Radio interference
 

Is this with the engine running?

It's not likely that a brand new switch is causing RF. A loose connection or metal to metal contact is the first place to look. Then see how far you can get with one section of the antenna extended.

If you have the ability, try switching channels.

Good Luck!!

RE: Radio interference
 

The plane is brand new.

The receiver is located inside the left wing and the antenna is stretched out along the wing towards the wing tip on the outside of the plane via a hole I drilled in the wing sheeting and stuck on with clear tape. It doesn't run past any servo arms or metal bits - the wing tube which runs inside the wing is carbon fibre tube.

All pushrods and servo arms are made out of carbon fibre. The pushrods are connected to the servo arms with HD ball links with the exception of the throttle which uses a simple metal wire with a z-bend in it at both the servo end and engine end (a possible candidate for interference??)

I did try the receiver and battery outside the plane. When I first had the interference, I removed all the radio equipment (receiver and battery) and tried a spare servo on every channel just to make sure it wasn't the receiver, it all checked out ok.

I thought it might have been a loose connection as there are 3 servo extensions in use so I pulled all those out and checked them and rejoined them with heat shrink tube before putting them back in the plane again. All connections on the receiver seemed solid with no 'looseness' in the connections. All pins on receiver and servo connectors seem to be ok to me, couldn't see any bent pins or female ends that had been pushed in.

I'll disconnect the throttle from the engine and see if that makes a difference as that is the only metal to metal contact on the whole plane. Come to think of it, I've never had that sort of setup before, I've always used plastic clevises on the throttle connection. I'll also check the battery - it is attached to a tray with cable ties and if I got too strong when tightening them up I might have caused some damage.

Thanks for the suggestions, I'll make a few changes tonight and see what happens. The plane has been sitting on my bench for too long now, it needs to fly !!!

RE: Radio interference
 

Ditch the carbon fiber servo horns if they rely are CF.

That metal to metal contact on the throttle is the culprit, almost guaranteed.

RE: Radio interference
 

Take the antenna out of the carbon fiber tube. That's what is blocking your signal from getting to the receiver.

Ken

RE: Radio interference
 

agexpert - What is wrong with carbon fiber control horns? The jet guys use them all the time as do many others.

Ken - He never said the antenna was INSIDE the carbon tube. In fact, he said the wire was OUTSIDE the plane. It's taped to the outside of the wing.

Does the problem occur with the engine off or running? If it happens with the engine off then it is NOT the throttle linkage. Obviously non-running engines do not vibrate and cause RF noise problems.

If you truely suspect the switch, simply bypass it with an extension wire running from the battery direct to the RX.

I'd disconnect all servos and reconnect one at a time and see what the results were.

Is it possible the RX antenna got damaged internally somehow?

RE: Radio interference
 

He said servo arms were CF, not control horns. That is what I meant, I have never seen CF servo arms, I would eliminate those if they really are CF. Nothing wrong with CF control horns at all.

RE: Radio interference
 

The interference is happening without the engine running.

The CF servo arms are screwed on to the standard plastic round servo arms which is then screwed on to the servo.

I'll take a look at the receiver antenna but I'm pretty careful when it comes to handling the electronics so I doubt that I have damaged it but you never know.

I've got a few things I can try out now so I'll see how it goes and post up my progress and, hopefully, solution.

Thanks for the advice everyone.....

RE: Radio interference
 

That's what did it for me!

I had a "metal path" from the engine on back to the fuselage, and worst still the throttle arm on the engine (which was metal) was in direct contact with a metal "Z" bend.

I would get very nasty interference that would practically disappear when the engine was off.

RE: Radio interference
 

Glad you found your problem. Incidently, CF servo arms or control horns will in no way effect your radio reception, very safe to use.

RE: Radio interference
 

I agree that there is nothing wrong with the carbon fiber servo arms if properly installed. Many planes use them. I would not leave a metal to metal connection on the engine arm even though it is NOT the current source of your problem. It could add one later with the engine running.

RE: Radio interference
 

Rodney and Bruce,

I think some clarification is in order since this is the beginner's forum. I use CF push rods on my smaller gas planes they are great. HOWEVER, any place where CF could rub against CF should be eliminated. As you know, there is no inherent problem with CF contacting CF. Later on when the bonding adhesive wears off, and there is partial delamination, you will get carbon to carbon which will lead to radio problems.

This happens often as old CF reinforcement in say an older Fiber-Classics model begins to flex. The CF webbing begins to loosen and the individual fibers rub against one another causing RF. If you are unlucky, the RF will interfere with the FM band.

When you have CF pushrods and horns, they should have a plasic ball-link and never a metal z-bend. It's simply unnecaessary to have CF servo arms. I have seen many composite, lightweight, laminated servo arms which are far superior to Carbon Fiber. I have never seen a composite servo arm that is actually made of CARBON in use, (I have seen them advertized, but not in use in Giant Scale planes). Mostly, people just use that term to describe another light-weight composite material that happens to have some fibers running through it.

I have never seen an RFI crash caused by CF arms, linkages or control horns. I have seen 3 RFI crashes and heard of several others in which old CF reinforcement has worn and begun generating RF, causing PCM lock-out. All of these planes were composite airframes with CF reinforcement and LOTS of time. This is precisely why I avoid and encourage others to avoid any CF to CF contact wherever possible.

Sorry for the confusion.

RE: Radio interference
 

A bit of an update....

I eliminated any of the servos causing the problem today. I thought I had a problem with the throttle servo because when I pulled it out one of the three wires was slightly damaged. I put a new servo in but still had the same interference problem. After a lot trial and testing I can say that I'm reasonably confident the servos are not the problem.

I took the receiver out of the wing and placed it and the antenna on top of the wing with the antenna stretched out and was still getting interference so that sort of eliminates anything inside the wing being the cause. I bypassed my new switch harness and plugged the battery directly into the receiver and still, the controls would twitch.

Next is to eliminate the batteries. I have put two battery packs on charge and will leave them overnight then pick up again tommorrow where I left off. If the problem disappears with fully charged batteries then I guess my switch harness charge lead could be faulty as that's how I charged them the other night before going to the field.

RE: Radio interference
 

I think you've about eliminated everything except for the receiver. I would guess it's gone bad somehow. Try another receiver in the plane with the same servos, switch, etc. I bet your problem goes away.

RE: Radio interference
 

the saga continues....

batteries weren't the problem, two different packs, still interference.

i pulled the receiver and battery out of the plane completely, layed them on my work bench, hooked it all up with a spare servo and guess what.....still twitches.

i tried another completely different radio and receiver.....still twitches.

so it looks like i am getting some local interference from somewhere. i never used to have any problems at home in my worksehd before BUT i have a new neighbour now who just finished building his house about a month ago so i'm wondering whether they have some sort of device emitting a signal that is interfering with my radio.

best bet for me i think is to fully charge batteries and take the plane down to the field where i know it should be clear and range test it out there. i was getting interference at the club field last week but, as i said earlier, i did have a damaged servo so after swapping that out i'm really hoping the problem has gone because i have truly run out of ideas after this.

RE: Radio interference
 

Remember that a WiFi access point or wireless phone will cause your servos to twitch like crazy.

If I turn on one of my planes in my house, and do not have the radio on and close to the plane, all of the servos go nuts because of my home networks.

RE: Radio interference
 

Hi everyone

Sorry if i have bumped this thread but i found this on www.yahoo.com after doing a search on RC Plane Interference.

My problem began a few months ago when i first started out on the plane flying business. One day we where just flying the plane when the radio gear just cut out and the plane did not respond to anything we did. The strange thing was the plane twitched and then dived really fast into the ground crash. Now my first reaction was ok its a old plane anyway this was bound to happen. The next plane we brought was still old and that did the same thing despite range checks and all sorts of precautionary measures. So we got a new plane and then the radio gear which was brand new did not respond and the plane flew straight for over four feilds and smacked right into the ground. Now the most weird thing was that when i went to retrive my crashed plane was the way it crashed. In a diagonal position with the engine supporting the planes weight. The area where this happens has trees and pylons near it which i think is causing the problem but other people are having the same problem with there planes and theres do this to.

Here is a picture of the area

http://img217.imageshack.us/img217/7...defarm2gj2.jpg

The black ciricle is where the trees are and you can see the runway the small green field. Its strange why would a brand new plane with new gear and everything just lose control and fly for as far as four massive fields and then decide to crash. This seems to happen in that area. Yet others have flown around there without a problem others have.

So what do you guys think that it is that could be causing this problem for me and others.

RE: Radio interference
 

Are there any crop circles in the area?

RE: Radio interference
 

Same transmitter?

RE: Radio interference
 

fjaust, did you figure out your interference issue yet? The one suggestion that no one mentioned is "OVER CHARGED" batteries. Some times when you charge the packs, the voltage is a little higher than what you'd exspect it to be, the receiver is getting over powered and will cause the servos to twitch. Sometimes just leaving the receiver on for 10 minutes will draw the power down and the twitching goes away. Please keep us posted so we can all learn from your experience. Chris

RE: Radio interference
 

Funny you should say crop circles

When i used Windows Live Local and had a look around the whole area i found this weird looking patch that was entirely red its kind of odd i mean look at it

http://img257.imageshack.us/img257/3...rdfieldjy3.jpg

I can give you guys the location if you want to see for yourselfs but what the hell is that?

RE: Radio interference
 

GAZ BE ROTTEN,Pylons????, these must be what we call power poles from the utility company. That appears to be a large farm operation, with I'd assume large power demands and plenty of electric motors running. That could be causing your radio interference. I do not know what frequency you use but there, but there is probably a simple frequency channel tester availible through you hobby shop, that would show what channels are being used or are being hit on from stray signals from the farm or utility company.

RE: Radio interference
 

We tried running one of them and found nothing the problem is its not just my plane thats done this but others as well continious times

RE: Radio interference
 

Radio interference isn't magic, it has a cause. whether it is internal or external is the question.
fjaust I'd try running the antenna down the fuselage instead of the wing. that way the end of the antenna is away from you while you're down wind and up wind. remember antennas work best with the longest side to you not at the tip. I think your problem is you're over driving your receiver. In other words you're just too close to the receiver and putting out enough of a signal that it causes the receiver to move all the servos. Try walking away 10 ft or so and see if the twitching stops.
Good Luck