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*RF Or EI Problems*

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Old 08-06-2006, 01:26 PM
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Zippi
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Default *RF Or EI Problems*

I am flying the GSP Giles 202 with the Brillelli 26cc engine. From day one I have been getting little glitched and it has slowly been getting worse. I have changed everything on the plane as far as the setup and checked for any metal to metal contact and I still have the problem. Before I flew the Gile 202 for the first time I range checked it and it was ok. We did a range check today with the engine running and couldn't get more than 75' away with the antenna down before everything went wacky. My question is, could there be something in the EI causing this? I think I have ruled out the setup since everytning has been gone over. Some of the guys at the field say it's the EI and some say it's the receiver. What would be your take on this guys?
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Old 08-06-2006, 01:53 PM
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jlingrel
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Default RE: *RF Or EI Problems*

You might try changing channels. Easy enough if you have a Spectra or similar module for your tx.

John
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Old 08-06-2006, 02:10 PM
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Default RE: *RF Or EI Problems*

This question brings up something I have wondered about, a grounding system in the plane. It would seem to me that an engine swing a plastic or composite prop in very low humidity would build up a static charge that could jump into the electronics. I was working on my idle the other day and when I would touch the screwdriver to the needle valve, or bump it on the muffler, all my servos would chatter. My transmitter was setting within thre feet of the plane, and the Transmitte/receiver I'm using field test OK at a couple hundred feet. I pulled the antanna up half way, and the problem went away, so it is noise. I don't see a source of noise other than a static build up.

I had a lot of experience working out EMF/RFI issues on computers, but the basics of a single ground point really doesn't apply to model aircraft. I was wondering though if one could build a ground system in a plane and disipate the static through small needles at the wing tips? I seem to remember that full scale planes use something like that to blead off a static charge. Am I all wet on this, or has someone tried this?? I think some of the metal pushrods are collecting the static and providing a path for emi charge.


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Old 08-06-2006, 03:21 PM
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Default RE: *RF Or EI Problems*

Don - what you most likely experienced is metal-to-metal noise when you touched your screwdriver onto something metal. Rub two pieces of metal together and they can generate a broadband electrical noise - that's why things like metal clevis connections on metal throttle arms aren't a good idea..

The static bleeds on full scale airplanes are most likely for when they're flying through static charged clouds, which we don't normally do with our models. I would think the static generated by a plastic prop would be pretty minimal compared to that, but I may be wrong, too! I've been wrong plenty of times before..
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Old 08-06-2006, 06:03 PM
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Default RE: *RF Or EI Problems*

Since the glitching problem doesn't happen close to the plane, just when it gets out about 60' to 75' I'm thinking more and more that it's the receiver. It's like it's lost is range for the signal. I can taxi around on the runwayand have no problem but once I get in the air and away from myself the glitching starts. It's not all the time, just hit an miss.
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Old 08-06-2006, 09:35 PM
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Default RE: *RF Or EI Problems*

Try another receiver. A friend of mine had that problem this weekend. He had installed a brand new PCM (JR) receiver and the control surfaces would not respond instanteously to stick command. They would respond but there was hesitation. Installed a FM receiver and the problem went away completely.

That new receiver is going back to JR.
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Old 08-07-2006, 11:14 AM
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Default RE: *RF Or EI Problems*


ORIGINAL: Campgems

This question brings up something I have wondered about, a grounding system in the plane. It would seem to me that an engine swing a plastic or composite prop in very low humidity would build up a static charge that could jump into the electronics. I was working on my idle the other day and when I would touch the screwdriver to the needle valve, or bump it on the muffler, all my servos would chatter. My transmitter was setting within thre feet of the plane, and the Transmitte/receiver I'm using field test OK at a couple hundred feet. I pulled the antanna up half way, and the problem went away, so it is noise. I don't see a source of noise other than a static build up.

I had a lot of experience working out EMF/RFI issues on computers, but the basics of a single ground point really doesn't apply to model aircraft. I was wondering though if one could build a ground system in a plane and disipate the static through small needles at the wing tips? I seem to remember that full scale planes use something like that to blead off a static charge. Am I all wet on this, or has someone tried this?? I think some of the metal pushrods are collecting the static and providing a path for emi charge.


Don
When you touch the screwdriver to the engine you are disapating the static charge on your body in the form of a spark that generates noise.
The spikes on an aircraft wing serve to discharge the static charge in the cloud before it builds up to enough voltage to cause a strike that we call lightning. Check out how a lightning rod works.
Metal pushrods can build up a static charge that will create noise if there is some other metal that is in intermittant contact with it.
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Old 08-23-2006, 10:59 AM
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Default RE: *RF Or EI Problems*

Zippi --- have you found and corrected your RFI problem yet? I have my first gasser and mounted it on a 1/4 scale scratch built plane and had similar problems. I removed everything from the plane and mounted the receiver, 4 servos, and a battery on a board and still had the severe servo twitching problem when the engine was running. I put the engine on a test stand and still had the same results. I tried 4 different Futaba PPM transmitters and 4 different receivers --- three different channels --- same results. I have been working with the engine manufacturer and the ignition manufacturer . I also wrote to Futaba . We tried two resistor spark plugs and three ignitions --- all with the same results. With the antenna down and about thirty feet away all of the servos chatter. So far the plane has not flown and will not until this problem is solved. I am totally out of ideas. I will say that the "BOSCH" style ignition did seem a bit better but not good enough for me to fly the plane.
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Old 08-29-2006, 07:55 AM
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Default RE: *RF Or EI Problems*

We did figure out Zippi's problem. He changed what he could on his end and the glitch was still there. I replaced his EI with a Bosh cap EI and the problem was solved. There must have been a problem in the EI unit. Very Rare. CH is going to test it and see now, but Zippi's glitching is gone so we are both happy
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Old 08-30-2006, 08:45 PM
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Default RE: *RF Or EI Problems*

flynfish44,

With the help from Scott (poco242) at Brillelli engines the problem has been solved. Even though I swapped out the EI and the problem was cured, I'm like Scott, this is rare so I'm curious as to what CH finds out on the EI I sent back to them. If the EI checks out I haven't a clue as to what the problem was but I do know it was something with the EI. It could have been a bad wire, or loose wire, or maybe the connections were not making contact very well. You have a tough one like I had. Did you try disconnection one servo lead from the receiver with the engine running and if the glitching continued plug it back in and try another lead? Make sure someone has your TX and has the antenna down and away from the plane with it glitching. You could have a bad servo or lead or extension. I know it's hard to pin down just where the problem is coming from and especially since your new to gas as I was it's even harder since you really don't know whats going on. Make sure and check your ground wire on the block. I wrapped mine around the spark plug and secured it with a hose clamp. Let us know how you come out on your problem.

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