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From: "Greenbacks, UnLtd." <n4zq@verizon.net>
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Subject: WX500 / S Tec pitch servo
Date: Sun, 19 Jan 2014 19:56:36 -0500
Message-id: <A49BD8C5-5294-4FA4-A95F-69D58B6C2363@verizon.net>
To: List Lancair Mailing <lml@lancaironline.net>
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So picture 4ZQ resting peacefully in her hangar. Power on, WX500 on as =
well as the Apollo MX20 which displays lightning strikes from the =
Stormscope antenna.
There are nine fluorescent light fixtures overhead and when turned on, =
each is clearly shown on the MX20 in relative position to the plane. =
Normal.
The WX500 antenna is located in the floor behind the co-pilot seat and =
about 12" forward of the baggage bulkhead. The STec pitch servo is =
located as per installation drawings on the right side of the elevator =
pushrod tunnel. In the air and with autopilot off, the MX20 display is =
quiet. Turn AP on and the display begins to show random strikes all =
around the plane. Turn AP off and clearing the display makes the problem =
go away. So it would appear that EMF from the pitch servo motor (which =
is constantly twitching ever so slightly, while waiting for the altitude =
hold clutch to engage), could be the source of my problem. I'm going to =
try to shield the pitch servo motor in a sort of Farraday cage using =
copper wire screen mesh and see if this helps. Anybody else with a =
similar problem/solution?

Angier Ames
N4ZQ=