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| General RC Aircraft Discussion Discuss anything RC related |
Topic Review (Newest First)
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| 09-12-2016 07:19 PM | ||
| Crash alot |
Re: Radio interference Thanks Roger. It looks like a dogs breakfast but it is "good practice" when it comes to wiring of sensitive electrical equipment. Until this plane I never had to give it a whole lot of thought. I have bigger planes with far longer/ lighter leads than what is in this plane (guess I had been lucky). I had never considered power draw or induction problems because they didn't have this much effect. There has to be something different in this plane and I hope it doesn't "attract any dirt" Lol, before I really figure it out. The Airtronics swap is a good patch but I still want to know what is causing all the noise and deal with it before the "black bag" comes out. Always bad when that happens! |
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| 09-12-2016 05:00 PM | ||
| RAMJET |
Re: Radio interference with long straight servo leads and metal wing supports I don't think you could make a better antenna for attracting dirt LOL . I'm assuming you have servo leads running in the top and bottom wing ?? I remember back in the old days Ron Chapman used twisted wire and noise suppressors soldered in the wires to help with this problem . this was a common problem with 72mhz on larger planes with long leads. you will need more than a few twists to have any effect (what you are dealing with is electromagnetic induction) when a conductor(straight wire)cuts through a magnetic field(power source) a voltage is induced . all current carrying wires produce a magnetic fields, if that field crosses through a conductor(straight wire) it will induce a voltage . when you twist the wire you cancel most of the induced voltage from the servo power to the signal wire. you will also reduce the ability of the signal wire to pick up induced voltage from other external sources . when you twist the wire you have a stack of small magnetic fields that cancel each other ,when straight you have a long continuous field that can induce or have induced a large voltage. regards Roger. |
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| 09-12-2016 04:59 PM | ||
| Crash alot |
Re: Radio interference Gary I have 2 transmitters. A T7UHFs and a CAPs and both have similar modules in them. I have traded the modules and corresponding crystals (1 is a channel selectable, the other is channel 56) and tried both radios as well with no change. Are you saying you might have a 2.4 module and receiver to sell? Lol ( I have 7 aircraft!) .. Quote:
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| 09-12-2016 04:14 PM | ||
| Cougar429 |
Re: Radio interference The whips are likely base-loaded, similar to the REVOS used on all my 72MHz helis and Deans bonded to my foamies. What that means is the receiver still believes it has a full length antenna. Berg receivers are internally base-loaded so you could cut the antenna into fractional lengths and still work. albeit with corresponding reduction in range. I cannot remember if you posted what transmitter. If module-based I could send you a spare module and Berg Rx to try. |
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| 09-12-2016 02:09 PM | ||
| aquila |
Re: Radio interference The whip is easy to install. I don't remember the amount for sure but I think it's about 6-8" away from the receiver you cut off and then just solder the connector on the whip to the end of the antenna it might not be the answer but you're not hurting anything by trying. The other thing I was going to suggest, you tried a different receiver but did you use the same crystal? I had crystals that developed cracks in them and at certain throttle settings I would have issues like you are describing. |
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| 09-12-2016 12:53 PM | ||
| Crash alot |
Re: Radio interference Thank you Jeremy. 1st of all you must like reading as this is a long and confusing post. I have since also installed a 2900 ma 6v NIMH battery as I can never get enough power! Lol. It just did not seem to matter what orientation the antenna was in. Laying on the ground away from the plane was the worst position. I do like the look of the whip. I have one here but I have been scared to use it. I don't like cutting the antenna wire on my tx. (I will have to look into the installation instructions that came with it..Lol) Luckily I did get 6 flights on it before I realized how bad it was and didn't thunder it in. (And BTW.Sounds to me like you have a nice fleet of aircraft!). I will have to switch over to 2.4 when I need to but I cannot justify it for 1 plane when all 7 other planes/ heli's are not having any problems with my 72mhz system. But I do like the look of some of the new radio's and the prices aren't that bad either.. |
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| 09-12-2016 11:59 AM | ||
| aquila |
Re: Radio interference I just read this entire thread and here are my 2 cents. First of all, a 5 cell NiMh 2300mah battery is more than enough for what you need. ALL of my jets use NiMh battery packs, 5 cell. My Bobcat uses 1600mah, but I do use dual packs. They are all digital servo's. My Firebird has 10 digital servo's in it and I have never had an issue in 16 years of flying turbines. The radio issues I have had in the past while flying 72mhz in the jets were typically due to the antenna running down the fuselage next to the pipe. In my Exocet I cured this by putting a deans whip antenna on my receiver and having it exit the fuselage vertical to the fuse. The whip antenna is only about 6" or so long and it solders to the existing antenna after you cut it off I think about 6" from the receiver. I used that method on my First Kangaroo, my Exocet, and my Gripen. I never had a glitch in any of those jets. Then one day while flying my BVM Kingcat, inverted at full throttle, just as I pushed out I went into failsafe, my engine shut down and fortunately as I had just started pushing out the jet continued to climb and the radio signal came back. I was able to land. That jet had the antenna running down the leading edge of the wing but after that event I was never able to get it to stop going into failsafe on the ground. I changed out everything, receiver, extensions, even the turbine pump and ECU. Eventually I bought a 2.4 module and converted my 10X and had no more problems. The only issue I ran into after the change was once I went to 2.4 I had issues with the Y harness on my elevators, it was an amplified Y harness and I was told the amplifiers did not like 2.4. I changed that out and had no more problems. Incidentally that jet was using a duralight powerbox with Lipo's, not NiMh. All I can figure with the kingcat when it was on 72 was eventually the module in my transmitter was going as it made no difference with different receivers etc. I couldn't be bothered to buy another 72mhz module so made the change to 2.4. It's not much help, but if you can find one a $20 deans whip antenna might solve your problems. |
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| 09-12-2016 11:45 AM | ||
| Crash alot |
Re: Radio interference Thanks Ken I have actually went as far as remove the landing gear and all metal components that I could. It would seem that there is something in/on the airframe that produces "noise" to the extent that it glitches my PPM radio. I have not tried a PCM rx as I dont have one and from what I have read it may just mask the problem. I have even ran the plane with the rx on the ground beside the plane and it yielded the same result. Now for the positive results. I borrowed a "inexpensive" Spectrum 2.4 from a friend (DX6i?) and installed it. No glitches at all (No one is surprised I bet) and I did an abundance of testing. No glitching. Then I installed a Airtronics 94102 rx and used my VG6DR tx and found that even in a crappy install (wires all over twisted up with the antenna and stuffed in the radio compartment) the radio performed flawless. Absolutely no glitching from any angle, orientation or throttle position. The only way I can get a glitch is if I touch the antenna to the metal on the plane (thats normal)..... Len you had the right idea. I wish you had come up with that 2 weeks ago...Lol |
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| 09-12-2016 10:14 AM | ||
| stegl |
Re: Radio interference In one of your pictures you are running the ant back over the receiver right near the servo wires. Try turning the receiver so the ant exits directly out the back with the servo wires at the front ; away from the ant..... Just a longshot but a thought. |
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| 09-12-2016 09:22 AM | ||
| cf100 |
Re: Radio interference Quote:
You removed the metal wing struts and no glitch, it would seem that there is some metal to metal contact rubbing on this model at idle that is causing your FM to glitch. Do you have a glow driver? Have you done any testing outside the shop? Have you done any testing out at the field, have someone observe the plane while you walk further away and record your findings. Sometimes having the TX to close to the RX swamps the RX and causes glitching. The combination of the metal lg, wing struts, jury struts, wing tube and being in a shop sets a situation where the FM signal gets distorted. I remember at certain r/c fields, you could expect a glitch in certain areas while flying FM, just the way FM was. a lot of the FM stuff off the used market is old, been crashed, dropped, just old electronics, you've got some nice planes, this Xmas, treat your self to a good 2.4 radio., if you buy 2.4 used, send it in to the Horizon or Futaba for a check out. Do you know Brent C or Earl P at the Brandon club or Trevor in Estevan, they might be able to help too. Let us know how this plays out. cheers - ken |
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