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Linda. You described in very detail the structure of a shielded wire. The shielding is supposed to deflect any electro-magnetic fields that are being produced by the current of the shielded wire. The idea is that if the shielding is connected with the casing of the magnetos or the respective electric part the wire is going to like the spark plugs for example. Some are claiming that both sides of the shielding need to be connected to the casings, some claim this to be nonsense and demand that only one side is to be grounded. Everyone agrees that it important to have the engine properly grounded to the airframe in order to see an effect on the shielding. Close to the engine mounting points should be at least one thick braided wire connect engine with engine mount. However. I am hunting ignition noise since I am having my Coupe. I tried everything. I have all electrical parts grounded properly. The antenna out and in, checked for a proper ground connection there. I have the p leads replaced with brand new shielded wires. I had magneto filters and added another layer of extra shielding. All with not much effect. I am having a Terra com installed and I found in the installation description mentioned under "Noise and Interferences" that in some cases noise or interference may be subdued but not eliminated. With the inefficient and imperfect platform provided by the aircraft... complete elimination of the problem may be very expensive or impossible... So Terra. My experience is to get to the source of the noise. This is for ignition noise - the spark plugs and the wiring. I replaced ones the spark plugs and had half the noise disappear just like that. Good clean contacts inside of the plugs are important too. The P-lead had almost no effect to ignition noise on my plane. Hartmut ----- Original Message ----- From: "Linda Abrams" <[EMAIL PROTECTED]> To: "Ercoupe Technical Discussion (moderated)" <[email protected]> Sent: Thursday, March 15, 2007 7:22 AM Subject: [COUPERS-TECH] P-lead wire shielding question > ----[Please read http://ercoupers.com/disclaimer.htm before following any advice in this forum.]---- > > > I hope I can describe this well enough to make my question clear. There is > a white wire coming out of a large nut on the aft part of the magneto unit > in my 415-C 'Coupe; I'm told it is the P-lead. Its outer layer looks like a > smooth white plastic insulation; then under that is a cloud of some very > fine, fuzzy (braided?) wire that I'm told is shielding. Under that, another > inner layer of more whitish plastic (more insulation?). Presumably, there's > also another wire at the core of all that somewhere; it appears to go though > a hole in the center of the large nut. The very fine layer of metal wire > shielding is just rolled back loosely over the outer white insulation, i.e. > it is not attached under the large nut. This was squawked by a mechanic who > saw it and said the shielding is supposed to go through the same hole in the > large nut that the inner part of the wire has been stuck through, and get > fastened down firmly under that nut, not rolled back loosely over the outer > layer of insulation and attached to nothing. Can some of our experts > confirm this or correct it? And, if he was right, what are (or can be) the > consequences of that shielding not having been connected to anything? > > Thank you! > > Linda > ============================================================================ == > To leave this forum go to: http://ercoupers.com/lists.htm > > > > ============================================================================== To leave this forum go to: http://ercoupers.com/lists.htm
