Is there anything I can wrap batteries and wires in to help prevent them from carrying ignition interference back to the receiver?

why not try resistor plug?

HUH? Don't know what you mean.

Crash . .if the secondary "sparkplug side" of the ignition is putting out enough interference to saturate your igntiions battery leads and battery with voltage spikes strong enough to cause interference, the receiver and radio wiring is already taking quite a beating from it.

Think of it this way .. the BATTERY and switches on an ignition handle about 6 volts, with on-off "spikes that range from 30-100 volts usually. These are VERY tame compared to the actual firing voltage of teh sparkplugs, which can exceed 20,000 volts easily. That's 200-600 times stronger of a voltge spike (with attendant RF interference).

I routinely have my receiver and ignition batteries withing 6" of eachother, as well as having other radio related items, such as servos, in the firebox or within 4-5" of the ignition itself. I've never experienced interference from this. . EXCEPT when one of the sparkplug leads or plugs develops a problem. Then, it does not matter if all my radio gear is 3 feet away. . I get glitches.

Case in point. .for 125 or so flights my 2.6m Fiberclassics Extra flew fine. . then one day I took off and had NOTHING on the radio. .I managed to get the engine throttled back and regain control (obvious ignition interference problem there) and landed. My post landing range check was less than 25 feet, with antenna collapsed, even though it had jsut passed a 200' range check when I first ran the engine. the problem? One of the spark plug terminal ends developed a problem and had an air gap of at least .020" between the terminal and plug. . caused so much interference you could hear the engine running on my van's radio, on the AM band, 40 feet away!!

Quick rule of thumb. . at least 6" and 18" is a better idea. . but if you get a SERIOUS RF problem from an ignition, you can have all the radio components in the tail, and it won't matter a bit. Make sure the ignition leads are good and undamaged, the plug caps make good clean contact with the plug, and all the wirign for the battery and switches is in good shape. . after that, there's almost no problem with interference.

Please keep a copy of this post and repeat it whenever one of our "experts" claims you must have several inches separation from the ignition system.

Bravo - Kris nails it !

Excellent post !

And a resistor type plug has gotta help too !

If one is available in the size of your plug. In most of the European engines it is not available

European 3W motors and American DA motors have a resistor in the spark plug cap and use a non resistor plug and a fully shielded ignition system.

European ZDZ, Moki (RCS), and MVVS use a resistor plug and a fully shielded ignition system.

How about BME?

BME uses a CH ignition, and there are some options.
Standard is a resistor plug and an unshielded ignition.

What are the options and what are their advantages? thanks

I own an RCS1.4,a 44B2 and a ZDZ80.
My ohmmeter tells me there is no resistor in the RCS engines plugs. I was told a resistor plug was not available in a 10 mm plug. Please tell me where I can buy one.
I don't have my 80 here to measure the plug but I bet it don't have a resistor in it either. If it did, why bother with all of that shielding? It just costs extra and would serve no purpose.

Oops, my mistake. If the RCS uses a 10mm plug (NGK CM6), then it's not a resistor plug. I bet there is a resistor in the plug cap between the high tension lead and the coil that contacts the spark plug. The ZDZ uses a Falkon ignition with Brisk plug or the replacement (NGK BPMR6F). Both are resistor plugs. A resistor plug is needed because the electronic timing circuit in the ignition may not work properly with a standard plug (according to the instructions that come with the ignition). Resistor plugs are pretty cheap (about $2.20).

For the BME, I think they have the small plug option, which uses the NGK CM6. The Extreme 110 shows this plug. Not sure if it uses a shielded ignition. Check with Keith Baker.

You can get resistor BRISK plugs from Canada.

BRISK Plugs

"Sorry Charlie" bad info.
The standard CH ignition uses a resistor plug AND a shielded resistor lead.
Next up is the Bosch cap setup. It uses a resistor plug, AND a shielded resistor cap with an non resistor(wire) shielded lead.

Okay. I can understand all that has been said so far. But can an Ig. devope a problem that will only show at a certain throttle/rpm range? Reason I ask is I lost a plane. Everything checks out fine but I know nothing about Ignition systems an these engines. First El. Ig. New ZDZ 50 only had 15/20 flights.

Withi things electronic all things are possible.
But normally RFI shows up at all RPMs.
While vibration induced problem are commonly rpm sensitive.

Today my 31% edge with a 3W75 gas engine crashed.

I took off, made a circle and was coming back around (took about 40 sec) when all of a sudden I didn't have control of the plane. It started a nose dive and went in at
about a 45 degree angle. I have been flying the plane for about 6 months now with no problems. However, today I moved the ignition battery farther back into the fuse to adjust the C.G. rearward. This put the ignition battery within 3 inches of the PCM receiver. It had previously been about 10 inches from the receiver. I'm not sure if the RF from the ignition caused this but it was conincidental with me moving the ignition battery pack close to the receiver (within 3 inches). I thought 3W ignitions are shielded.

Greg

An RFI problem from the battery being too close would not occur suddenly and wipe out your control. It sounds to me that you had a failure in your system like a broken wire or something like that.