Message-ID: <39CB92F6.53FB5337@ieee.org>
Date: Fri, 22 Sep 2000 10:12:22 -0700
From: "Charles R. Patton" <charles.r.patton@ieee.org>
Reply-To: charles.r.patton@ieee.org
Reply-To: lancair.list@olsusa.com
To: lancair.list@olsusa.com
Subject: Re: Vision Micro problems
References: <69.abcf5a7.26fbb2da@aol.com> <002501c02442$11d6b8a0$f196bf18@barkerasset>
Mime-Version: 1.0

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Robert R Barker wrote:

>  Disconnect
> the primary lines to the NAVCOM. In their place run  heavy gauge wire

Voltage drops on the ground wiring is a good possibility of the problem.  I
would remark that an easy alternate way to separate this from possible RF
susceptibility problems would be to disconnect the antenna connection at the
rack and connect instead to an RF dummy load.  Key the transmitter and see if
the Vision readings change.  If they still change, then Robert Barker’s
suspicions are an excellent place to start looking.  In particular, it may be
that both effects are present – both voltage drops on the ground wiring and RF
radiation into the sensors from VSWR and/or direct radiation from the antennas.
Being composite planes, you don’t get the customary shielding of the aluminum
structure.  The dummy load test is important to eliminate or implicate the RF
source in your investigations.

Charles R. Patton
N360JM


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