Multiple radios giving intermittent problems
 

Evening everyone.

We've been having some problems the last few weeks with different Spektrum radios and receivers. First problem was using a DX10 transmitter and different receivers. The first plane showing issues was a Carbon Cub, 30cc gas power. The plane range checked properly and we actually went several hundred yards away from the plane in multiple directions with good results. We set the tx back to full power and flew the plane for the first time. All was well for about 2 minutes and then I lost radio contact and the plane just went nuts. Thirty seconds later I regained control, then lost it, got it back and lost it. I managed to get it throttled down and landed safely. I didn't set this plane up but close inspection shows no crossed wires, the antenna routing was correct and no obvious interference from the engine ignition. We range checked again and all was fine. Plenty of battery power but the same results a second time. Got it down safely again. Next week installed a new receiver, checked everything but got the exact same problem. Set that one aside...the owner brings out a recently purchased TaylorCraft that I know was flying properly because I flew it several times. This time it was using a different receiver that came with it when he purchased it and was definitely NOT one of the first two. Range checked properly again, all the control surfaces were moving correctly. Took off and flew for about a minute and it all went bonkers again. I fought it as best I could but this one ended up going straight in. It just gets better, The next week I am helping a new pilot with a Kadet LT 40 powered by an OS 46FX. I assembled and test flew this plane and it flew great, no problems. It has burned nearly a gallon of fuel without issue until Sunday. Took off and about15 seconds in the plane goes into a left hand circle and won't come out. Left aileron, rudder, no help I got it to throttle back and the engine quit but had no other control at all. It was banged up a bit when it landed but not too bad. When we got back to the pit everything was working properly. So that is three different planes, different transmitters, four different receivers. At least two planes had many flights and showed no signs of trouble. Then in two different flying sessions two are damaged/destroyed and one is just sitting for now. Two different modelers both with at least some experience. I'm at a loss. No one else is having these problems so I don't think there is an interference issue of some kind but have no idea what it could be. The DX 10 has been sent back for a checkup and the DX8 is still here. My best guess is that something is up with Spektrum because no one is having problems with Airtronics, Futaba and JR at the same field, same day. Batteries are good and a switch problem seems unlikely but possible. Any ideas? Thanks.

Rick H.

2.4ghz is not bullet proof as many think or claim. While many manufacturers use 2.4 their frequency hopping operation differs from brand to brand. There can be some sort of field interference that Spektrum has difficulty coping with. Spektrum tends to dominate many flying sites so someone there may have a system wildly out of spec. Likewise tons of Chinese made 2.4 junk is common.

Technically 2.4 devices are not supposed to interfere with each other but with the plethora of 2.4 devices from garage door openers, security cameras to eBay RTF stuff there are bound to be many that slide under FCC's radar.

As a test try your system, or one that has experienced this issue, at another site or location. This will help isolate the equipment or location issues.

I suspect a angry person is jamming your signals. Or a spoiled brat. I have tracked down a couple of people laughing as the caused just such. problems/\.

A cell tower that is not right can also cause interference. The transmitter is over tuned on power & generates massive bursts of SPLATTER frequencies.

Hello: Well 2.4 stuff can be tricky at times. The receiver must be installed properly, not just jammed in the fuse along with all the other radiating wires. take your time and locate the receiver properly. Use good connectors, some Chinese stuff if really bad. A lot of transmitters today have really dumb gimbal set ups. By this i mean the wires connecting to the control pots actually flex when you move the sticks. The more you fly the worse it gets. Open the transmitter and move the control sticks, if the wires move there is your possible gremlin, and trust me when I say it is very difficult to diagnose and very very intermittent. I had 3 transmitters that did this to me and they all had flexing pot wires. My old Futaba conquest 4NBF I think was the name, the wires did not flex and that radio never had an issue with any broken pot wires. I have seen far more crashes with 2.4 stuff then I ever saw with the low frequencies. So troubleshooting can be tough. Servo connectors are crimped, not soldered, so there is a possibility. I use to put a drop of 3 in 1 oil on each connector before i plugged them into whatever i was connecting, why you ask? To keep the oxygen away from the contacts so they would not oxidize and corrode and cause a poor connection. In the old days with AM you could pretty easily identify interference, then also with FM, but was more difficult ( I am not talking about some one else on your frequency). I just find the the new 2.4 stuff is more finicky, everything has to be right or the gremlins might get you. In the old days you flipped the switch and the radio was on, did not have to Boot up, same goes for these computer receivers, they have to boot up every time the supply voltage dives below threshold, while it is doing this you have no control. If your receiver takes a long time to boot, the closer to the ground you will get. Its a crap shoot, just make sure things are right and pay attention to detail when installing your radio equipment. Good luck and happy flying...