A friend used to live in the shadow of the WBNS radio tower in East= =20 Columbus Ohio. He would get WBNS day and night on the TV with the TV turne= d off.=20 He had to put a switch in line with the speaker, and that just cut the vol= ume=20 down. He also got WBNS in the silver ware drawer. If the radio sounds stop= ped,=20 you just juggle the drawer to get different pieces touching each other and= the=20 radio came back on. Some people got it in their teeth fillings. Ladies pic= ked it=20 up in hair curlers. A crystal set kit worked before you assembled it. You= didn't=20 even need the tuning coil, so we had transistor radios before transistors= were=20 available.

In the plug wires you have 4 (or 6) radio stations. One end of the=20 broadcast tower is a spark gap, so it broadcasts on all frequencies.

That means that no matter what length wire is nearby, it is per= fectly=20 tuned to some of the noise you are broadcasting. So, no matter what any ot= her=20 wires in the airplane are supposed to be doing, they are always listening= to the=20 4 radio stations, and in the case of a low voltage application, induced vo= ltage=20 from the stations may overcome the low voltage application.

A number of methods are used to eliminate or reduce this problem.

Distance. Magnetic coupling is inverse to distance. Keep everything= away=20 from the plug wires.

Antenna size. Keep plug wires as short as possible.

Shielding. As in shielded plug wires. And shielded low voltage wires.=

I run my trigger wires for the MSDs through some dash 4 Teflon lined= =20 stainless braided wire, with the braid grounded.

Coil on plug systems. (No plug wires)

Smaller plug gaps. I start at .010" and go up to .015".

Inductive plug wires. Spiral wound Monel conductor wire from the hot= rod=20 shop. Eliminates radio noise in race cars. Otherwise the racing radios don= 't=20 work. I have read that those wires also make for a longer lasting and hott= er=20 spark, but don't all aftermarket products do that?

Lynn E. Hanover

In a message dated 7/2/2011 10:50:25 P.M. Paraguay Standard Time,=20 rwstracy@gmail.com writes:

Thought I had commented on this before. This symptom is most= =20 likely caused by impulse noise from routing the EGT lines too close to= =20 ignition leads or other high noise Sources. The thermocouples gene= rate=20 low level signals in the millivolt range so it doesn't take much to spik= e the=20 reading.

Tracy

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