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Date: Mon, 04 Jul 2011 11:54:42 -0400
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From: "pete@leapfrogventures.com" <pete@leapfrogventures.com>
Subject: RE: Noisy AeroLed nav/strobe lights
Thread-Topic: Noisy AeroLed nav/strobe lights
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I had this problem.  When my LED nav lights were on the front comm would br=
eak squelch at frequencies above 127mhz.  Both my comm  antennas are on the=
 belly, but the rear one was "shielded" by the wing (carbon fiber) and did =
not receive the noise.  Filter capacitors on the power lines will not solve=
 the problem, as the issue is noise emanating from the leads going from the=
 constant current power supply to the LEDs themselves.  Basically it is a n=
ice little radio transmitter.  There are three parts to the solution.  The =
first is to add 0.01uF disc capacitors to ground on the leads going from th=
e power supply puck to the LEDs.  The second is to add a 0.1uf disc capacit=
or and a 47uF tantalum capacitor on the power lead into the LED power puck.=
  Don't use electrolytics, as their radial design makes them ineffective at=
 high frequencies.  The third step is to wrap all of the electronics and th=
e area behind the LEDs with grounded copper foil (a Faraday cage).  Once I =
did all three of these, all of the noise from the LEDs went away.

Pete