Electromagnetic Interference Problem
03-08-2003, 11:12 PM
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Electromagnetic Interference Problem
Hi Guys,
I'm not sure this is the right forum for this but here goes.
I have a Zenoah GT-80 with C&H ignition installed in a H9 Cap 232 and it is giving me fits with EMI problems. I am getting 50 to 60% engine-on range and have tried nearly everthing I can think of to solve it.
Bill at C&H sent me a set of plug wire shields but that didn't help. The next step may be to send it back to C&H to have Bosch spark plug shields installed. I didn't do this initially because at the time they didn't have the short spark plugs and I would have had to cut the cowl. I understand they now have the shorter plugs. They said that shielded spark plug caps are rarely needed if all their precautions are followed and as far as I know, I followed them.
Before I do this I read an article in the Dec '02 RCM by Don Lowe about how he solved a stubborn EMI problem on a H9 Sukhoi by wrapping all the ignition components with metal tape. He doesn't say what kind of metal tape he used and I don't have his email address.
I have several questions. First, has anybody else had an EMI problem with the engine I described and second, what kind of metal tape should I use to wrap the ignition components like Don Lowe did. I tried wrapping every thing with aluminum foil but that didn't help.
Thanks for any help you can provide.
Bluesky
I'm not sure this is the right forum for this but here goes.
I have a Zenoah GT-80 with C&H ignition installed in a H9 Cap 232 and it is giving me fits with EMI problems. I am getting 50 to 60% engine-on range and have tried nearly everthing I can think of to solve it.
Bill at C&H sent me a set of plug wire shields but that didn't help. The next step may be to send it back to C&H to have Bosch spark plug shields installed. I didn't do this initially because at the time they didn't have the short spark plugs and I would have had to cut the cowl. I understand they now have the shorter plugs. They said that shielded spark plug caps are rarely needed if all their precautions are followed and as far as I know, I followed them.
Before I do this I read an article in the Dec '02 RCM by Don Lowe about how he solved a stubborn EMI problem on a H9 Sukhoi by wrapping all the ignition components with metal tape. He doesn't say what kind of metal tape he used and I don't have his email address.
I have several questions. First, has anybody else had an EMI problem with the engine I described and second, what kind of metal tape should I use to wrap the ignition components like Don Lowe did. I tried wrapping every thing with aluminum foil but that didn't help.
Thanks for any help you can provide.
Bluesky
03-09-2003, 12:19 AM
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RFI
See if anyone at your field has an CH ignition tester. It will run the ignition with out the engine running.
You may have a vibration related problem and not RFI.
Did you follow the installation instructions for the CH ignition,with no fudging?
You may have a vibration related problem and not RFI.
Did you follow the installation instructions for the CH ignition,with no fudging?
03-09-2003, 06:16 PM
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Electromagnetic Interference Problem
Hi Guys,
Thanks for the responses. I have been testing both with the engine running and with a C&H tester. Results are about the same. I'll try the metal tape and possibly change frequencies as a last resort.
Bluesky
Thanks for the responses. I have been testing both with the engine running and with a C&H tester. Results are about the same. I'll try the metal tape and possibly change frequencies as a last resort.
Bluesky
03-10-2003, 03:22 PM
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RFI
RFI a science??? more like a black art. Some time dancing around when its a full moon and sprinkling chicken blood on the plane works as well as anything 
Check the distancees on your installation, throttle pushrod, throttle servo location.
The instruction show the throttle servo on the firewall using a metal pushrod, both are bad ideas.
Check the distancees on your installation, throttle pushrod, throttle servo location.
The instruction show the throttle servo on the firewall using a metal pushrod, both are bad ideas.
03-10-2003, 04:46 PM
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Electromagnetic Interference Problem
Many do relate EMI to a Black Art... I worked with it for over 4 years in a testing facility, so I was able to learn quite a bit about commong problems. In this case, it appears on the surface that the EMI is from the ingnition, but the problem is how it is affecting the plane. There's two types of general RF emissions - radiated and conducted. Radiated is emitted from the device like it is a transmitter and conducted would be down a power or signal line. I'm assuming that it is radiated in this case, however not knowing the details makes that unknown. RF can even couple to long leads that act like antennas...
* Ensure that your ignition components are as far away from the radio as possible.
* Reduce any metal to metal contacts (ie throttle pusrhrod)
* Your receiver antenna should be routed away from any of the battery leads on the airplane's system.
The list goes on.... Obviously, test equipment to see what is going on is the answer but many don't have access to it. Let us know what you find out.
Michael
* Ensure that your ignition components are as far away from the radio as possible.
* Reduce any metal to metal contacts (ie throttle pusrhrod)
* Your receiver antenna should be routed away from any of the battery leads on the airplane's system.
The list goes on.... Obviously, test equipment to see what is going on is the answer but many don't have access to it. Let us know what you find out.
Michael
03-11-2003, 01:08 AM
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emi/rf
Bluesky,
only from experience, I have found some of the sources of interferrence, any king of metal to metal contact. linkages, connectors et.
ground strap rubbing on the side of an engine. bare covering on the hi tension lead from rubbing.
a servo wire to close or even touching any wire coming from the ignition box or battery.
I personally use a hose clamp to attach the ground strap to the base of the spark plug, also use nothing but the rubber boots supplied by C/H
good luck
only from experience, I have found some of the sources of interferrence, any king of metal to metal contact. linkages, connectors et.
ground strap rubbing on the side of an engine. bare covering on the hi tension lead from rubbing.
a servo wire to close or even touching any wire coming from the ignition box or battery.
I personally use a hose clamp to attach the ground strap to the base of the spark plug, also use nothing but the rubber boots supplied by C/H
good luck
03-16-2003, 05:28 AM
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EMI problem.
This thread is from a guy that had a lot of problems with a G23.
Very Helpful!!
Covered most posibilities.
http://www.rcuniverse.com/showthread...865&forumid=37]
Very Helpful!!
Covered most posibilities.
http://www.rcuniverse.com/showthread...865&forumid=37]
