Ohnoucdats thread made me finally decide to break down and ask for advice. I have a problem similiar to his except WITHOUT the engine running.

My Hog Bipe has flown successfully this year, maybe 20 flights total. When I turn on the transmitter and reciever, WITHOUT the engine running, the rudder and throttle "occasionally" (emphasis on occasionally) jerk. The throttle goes from closed, to maybe half throttle and back to closed within a second. Simultanous to the throttle jitter, my rudder kicks over the same direction everytime then back to neutral. A range check produces the same results whether near or far. Battery voltage has checked fine for both transmitter and reciever. As a matter of fact, I have replaced the reciever with a brand new one with the same results. On top of that, I use this transmitter with 3 other planes currently with no issues.

So, my guess is the problem has to be inherent within the Hog. I ran the antenna through the bottom of the fuse through a pushrod tube with the end sticking out of the tail as I have done with many other planes without problems. Granted, I have continued to fly the plane, although I realize that this wasn't the greatest decision I have ever made. However, the elevator and ailerons have performed flawlessly while only a couple of times the rudder/throttle issue has occured split second while in the air, barely effecting the flight since it happens so quickly.

Considering that winter has taken hold, now is a great time for me to correct the problem (I realize that the best time was when it happened the first time !) Does anyone have any ideas as to what might be going on?

RCKen, have you ran your antenna through the fuse and out the back on your hogs?

That's how I run the antenna on all of the Hogs I've had.

Ken

had the same problem when I first brought my Nextar to the field twitching with the engine running or not antenna was run through the fuse,but the antenna tube is run between the pushrods they are wire and was probably the source of interferance,it was the most obvious scenario for the interference problem.

easy solution done at the field, I opened a hole in the fuse,in my case the top, but the bottom would have done just as well, took a servo arm for a keeper and a small piece of fuel line pulled through the fuse so the antenna doesn't rub,put a T pin in the tail and used a rubber band to hold the antenna wire,problem solved.

if exposing the antenna to the outside of the fuse doesn't fix the problem then you might need to send it in for a check up.

Turn the transmitter on before the reciever

It is sometimes normal for the controls to oscillate once before centering at turn on

What channel are you on? some of the low channels, CH11 is one, are close to some paging towers. If you have access to a frequency anylizer, check the air when you are having the glitching to see if there is blead over from one of these towers. The little Hobico frequency checkers will not give you a good picture.

I took our clubs anylizer to Savannah in Oct when I went out to visit my son. I had been incomunications with one of the guys on this forum and he was complaining of "hits". The day I was at their field, there was a very strong signal right next to Ch11. Any fuzz on the transmitter would easilly blead off into the CH 11 frequency. The other interesting thing at that field was that when two Tx's were on there was a lot of noise around both frequencys. Their field in on an old dump site and there is a lot of burried ReBar just below the surface and this screws up things at ground level.

All that aside, now that it building season, it might be a good idea to send your RX in for a checkup.

Like the other thread was saying, check for metal to metal on all of the servo linkages. I had one plane two years back the if the engine was running and I touched a screwdriver to the idle mix screw the servos went nuts. It was very repeatable once I figured out what was kicking it off.

Thinking back, even a loose clevis on a metal pushrod might be enough to introduce some RF noise.

Good luck in tracing it down.

Don

Wy8e, I always do this and always have (I'm actually anal about the order), but thanks for chiming in! This happens after Tx is turned on, then Rx.

BigTim, I intially thought that the pushrods might be the problem, but I used the stock plastic pushrod that came with the kit.

Ken, I think actually learned the antenna run method from you and Minnflyer, so I didn't think it could be cause for any interference.


I don't actually expect anyone to chime in with THE answer, but thought someone might have had or seen a similiar occurence. Thanks everyone!

Some of mine do this at times, I never gave it much thought as long as they stabilized

Campgems, I am using channel 12, however I use this same Tx and channel on many other planes problem free. Also, I live in the mountain in Eastern Ky and a cell phone tower is as common as seeing a pig fly !

As far as sending in the Rx for a checkup, this is the 2nd reciever with the same symptoms, and is brand spanking new. As a matter of fact, the original reciever that I took out works great on channel 12 in my new plane. I can't imagine that the rx is the problem.

Also, I have no metal to metal contact in the control linkages, even if so it happens when the engine is not running.

First, to rule out radio interference sources at the field, test the plane at home, away from the field, with the antenna down. If you're getting the same behavior, then I suspect a bad connection in a servo lead.

You may have cracked insulation, or bare wire visible somewhere along the servo wire between the reciever and the servo. One bad connection will affect some or all of the other channels. Start by unplugging all the servos, then plug them in one at a time and test. When the behavior returns, the servo that was last plugged in becomes the prime suspect. Take it out and thoroughly inspect (with a magnifying glass if necessary) along the entire run. Make sure there are no cracks in the insulation or plugs. If you have another servo try it in place of the old servo.

If there is nothing visibly wrong with that servo, repeat the test as before, but plug the servos in in a different order. If the behavior returns when you plug in the suspect servo, then you probably have a reciever problem, and you'll need to send it in for service or replace it.

Brad

It's interesting that both servos with the problem are connected to the left stick channels. Perhaps you could temporarily switch the servo connections to the other stick channels and see if the problem follows. Likewise, you could see if the elevator or aileron servo responds similarly when connected to the left stick channels.

r2champion

I had similar problem to begin with a friend unplugged battery from switch and straight to rx. It worked so got a new mpi switch, You could touch any of the sticks and the throttle would go it seemed to have fixed it with new switch till I did the range check with engine running. I did another range check with mine last night after a few fixes changing metal z bend on throttle getting antenna out of fuse, checking everything was plugged in tight, I think I'm good to go. I'll do another range check at field Sat. I'm also going bk and changing all metal to metal on my planes. The tiger was ok it's plastic throttle arm on the 46ax.

Nice catch , I wondered about this myself. I will give it a shot. The only problem with testing this is that it happens so randomly. It has happened at home, at the field, in the air, etc., but will go for a while without problems until suddenly it does it again, very unpredictable. If this problem occured during landing/final, I would have a hard time not crashing being lower to the ground.

Let me just restate to all that this Tx, and servos all performed flawlessly in another plane. The current Rx is a brand new replacement for the original Rx that I first thought was bad. Both Rx's create the same problem in the Hog, and the original Rx is being used flawlessly in another plane. This could not a bad reciever problem.

I will start switching around servos, replacing the switch/battery and hope that I can confidently fix it. Hard to be confident when there is no way to trigger the problem to test.

I have seen the condition described many times, and corrected it by putting in a new switch. Recently I realized that if the switch is bad it could happen while the plane is in the air and cause a crash. I now use better switches. They have gold contacts, heavier wire, and cost close to 3 times more. I'm expecting to get much more life out of them so the added cost is not a factor. I'm happier and that is what counts.

Do you have a 6.0v or a 4.8 v battery? I have seen 6.0s make some controls jump until it drops down some. I have also seen long runs of extensions do the same; braiding or twisting the wires has fixed that.

I run a 4.8v battery, however have benn contemplating using 6v. I thought also that maybe I intially had too much charge in the battery fresh out of being charged causing the problem, but it wouldn't come close to being 6v, so I dunno.

My suspicians thanks to your alls response is a bad link somewhere; either servo, battery, or switch. Time to start investigating. Thanks to everyone who has chimed in!