daveopam

My Feedback: (9)

After 20 years of flying I thought I had seen it all. I am not going to mention any brands here. I just hope someone can tell me if this is an RX problem or not.
So I get a brand new 4 ch radio to use as a flight pack. I take the RX and put it in a plane that is 10 years old with many flight on it. I don't change anything else. On the bench it all hooked up fine. I get to the field and turn the plane on. All is fine for a few seconds. Then I get full right rudder,full up elev and one aile goes down. The ailes are on sepperate channels. So I pick up the TX and move the elev stick. This makes the rudder wag. I shut the plane off and check my TX. I have seven models on it so I make sure it is on the right model. It is so I turn the plane back on same thing. So I turn the plane off and check the battery. It is fine. I also have this model in my TX twice so I switch to the other model. Turn the plane on same thing. It chattered for a second and did what it had been doing. I pump the fuel from the plane and decide to burn out what is in the tank. I turn it all on and it's fine. I run the motor for 1-2 minutes with everything working fine. No way am I going to fly it so I pull the RX and send it in for service. I sent a note saying what I had said above. I get it back yesterday with a note. "This RX passes the range and vibration test and meets out standards. You should check for interference."
So now I am mad. I can't trust this RX in another plane. I have seen interference do some strange things. Never though make the elev stick run the rudder. So now what. I have another new RX in the plane and it all seems fine. I have not had a chance to fly it. I have turned it on and off several times. It works fine every time. So is the RX bad? Could the TX be the problem? Will RF noise make the elev stick run the rudder?
Please give me some guidence before I call the company and loose my temper.

David

BTW- they should have sent a new RX to be on the safe side IMHO.

RCKen

My Feedback: (9)

Dave,
Problems like this can be very frustrating indeed. But from what you said it does sound like you have a bad receiver there. You said you bought a complete 4 channel radio to get the flight pack out of it. Have you tried using the receiver with the transmitter that came with it to see if there are problems there? That is what I would do to check it. If nothing else I would return the entire radio set and get a replacement. Too much involved to risk on a receiver that is questionable.

Hope this helps

Ken

MinnFlyer

My Feedback: (4)

That's exactly what I was thinking.

One other thing that came to mind is - You didn't want to mention brands, but were the Tx and Rx the same brand?

TEAMERICA

My Feedback: (77)

David, Based on what you wrote, I picked up on the above quote. Just to be sure of what you did.
Did this 10 year old airplane have 10 year old servos in it??? Because you said you put your new receiver and didn't say that you put the entire new flight pack in it.

Anyway, if those servos ARE in FACT 10 years old, they could be your problem. I have seen where a noisy servo (caused by worn/dirty pots - maybe even corroded from old age) can interject noise into your system causing all kinds of problems. It is conceivable to me that a (one or more) noisy servo could cause a severe enough impulse within your receiver to make the receiver "think" is has an extra channel pulse (or even mask a pulse) and thereby cause the following channels to be out of sync (elevator input works rudder etc.).

I had this happen to me back in the 60s when building a scratch built Digi Trio radio system from RCM articles. For some reason, the servos would start working on a different stick channel (elevator worked the ailerons and rudder worked the elevator etc). I didn't know why but it happened on the bench so much that I figured how it would fly if I just turned the transmitter sideways to the right and worked the elevator with the top stick and the aileron with the bottom stick. I was young and foolish (besides who would I send the radio to for repair anyway?) so I flew the radio in a Cessna 150 one day and "It happened" in the air. Because I had played with it on the bench so much, I knew what to do so I turned the transmitter sideways and flew the airplane down to a landing. I never flew that radio again and went back to my trusty 6 channel reeds.

Try replacing those old servos in that old airplane with the new servos in your new flight pack and go flying. The physical connection in the feedback pots is still one of the weakest links in our radios now-a-days (besides the brushes in the servo motors). They wear and corrode and there is nothing we can do about that.

daveopam

My Feedback: (9)

I did not use the whole flight pack. I only replaced the RX. This is what made me think RX problem right away. The plane has been flown on a regular basis. I only put the new RX in because I needed the smaller RX from this plane for a profile. So the only thing that changed was the RX. I guess a servo can go bad at any time. The Aile servos on this plane are 10 years old. The Rud and Elev servos were upgraded a few seasons ago. It just is odd a servo would go bad at the same time I changed the RX. So I guess I will change the Aile servos before I fly it. I have just never seen an RF problem make one channel control another. Until now anyway.

Minn it is the same brand RX and TX. I did not want to mention the brand because I knew someone would tell me to buy brand X and you wont have this problem. I will say I own both JR and Futaba radios. So it is one of those.

So how am I going to tell what fixed this plane? Would you guys trust this RX in another plane? I guess if I can get the problem to pop up again I could try the TX that came with the RX. But can I fly without 9 chanels,expo, and dual rates?????

Ken If you make it to Baxter this Sunday. Stand behind me when the yellow Ultimate is flying. I won't crash into myself. LOL
thank for the help,
David

RCKen

My Feedback: (9)

Dave,
Looking at the weather forecast there may not be any flying for anybody in Ok this weekend!!!

Ken

TEAMERICA

My Feedback: (77)

You don't have to actually uninstall and install the old aileron servo. Just unplug it and plug in a new servo. Keep doing this with EACH servo to determine if, in fact, a servo is the cause of the problem. You might even have to run the engine and do a normal range check since the vibration from the engine could be irritating the "bad" servo into causing the noise.


Well, You should be flying Airtronics. You would never have that problem with a good radio.!!!!!
There, I said it and I don't regret it.[:@]

daveopam

My Feedback: (9)

Ok, I am not taking radio advice from a guy who flies heli's from a unicycle. Now if you could fly a Yak 54 from a Yak(water buffalo). Then I'll buy Airtronics.

On a serious note. I will try to unplug the servos one at a time on a different plane. IF I can get the condition to show up again. If I can't get it to show up again I guess I am stuck. I just can't make myself use that RX in another plane. It would be one of those things you know better but did it anyway.

David

Clark L

David,
Unless you're running PCM, it sounds like another radio was transmitting on your frequency...

daveopam

My Feedback: (9)

I would have thought so to Clark. But I fly in a small club with 8 other guys. I am on 60 and the next closest to me is on 54. The RF noise could have come from somewhere else. Our field though is 8 years old. We have never had a radio hit that could not be explained. I also question the length of time I was having trouble. This problem lasted 5 minutes. We fly close to I-40 and I suppose a trucker could be way over and give us a hit. I just do not think it would last 5 minutes.

thanks for the input,
David

daveopam

My Feedback: (9)

Well I put three flights on the plane today. I had the wing off and tried both RX to try and get the problem I had the other day. No luck. So since the aile servos were 10 years old and I had made the wire extensions instead of buying them. I changed both servos and used HD extensions. Then I left the new RX in the plane put it together and put a flight on it. It seemed fine so I put two more flights on it trying to wring it out best I could. Everything was fine. So now I guess I will try the RX I thought was bad in one of my older planes and run a few tanks through it on the ground. I hope was was wrong about it and all is fine. I guess I should count myself lucky. It has not cost me a plane as of yet.

Thanks again guys for all the help,David

N1EDM

My Feedback: (2)

Daveopam,

Do you have a wire or chain link fence nearby when you range-check the radio? I've had this happen with a couple of birds. Inside the pits, for no apparent reason, everything starts wiggling like a ruptured duck. If I take things out of the pits, away from the wire fence, everything is fine.

My theory is that you might be getting some reflections off the fencing that are arriving out of phase with the main signal direct from the transmitter, sort of that 'ripples on the pond' thing we hear about every once in a while.

If things are positioned 'just so', this could be happening to you. I didn't think it was possible until it happened to me, twice. It might be caused by a combination of a signal arriving out of phase and an antenna from the new rx being run, perhaps more closely to a servo. The combination of an out of phase signal and some 'noise' from the electronics in a servo could be causing this problem.

The next time that this happens, try moving everything outside the fenced area and see if it changes. If it does, most likely the cause was something reflecting your antenna signal that is gone now. If things don't change, then like everyone else, I agree that the problem is with the rx or a noisy servo.

Just my $.02

Bob

daveopam

My Feedback: (9)

Thanks for that Bob. The table I assemble my plane on is about 10' from a chain link fence. I guess a combo of several things could have given me this problem. This was however before the range check. The plane and TX were 2' from each other. Also as soon as it happened I picked up the TX and pulled the ant out. The whole thing still has me scratching my head. At least the plane is back in the air. The final piece of the puzzle will be when I try the other RX in another plane. If I am lucky the prblem will never show up again.

Thanks to all again,David

Clark L

David,

One more thought.... Any chance someone happened to be on a buddy box while all this was going on? I've seen on several occasions where the "student" transmitter (on another frequency) was turned on without the instructor knowing it. In other words, both transmitters where on but the flag or pin was pulled for only one channel. Anyway, It sounds like you've done all you can do. Test it well in something you're not afraid of losing, just in case.

Clark