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Re: [RFI] shielding question

To: "RFI List" <rfi@contesting.com>
Subject: Re: [RFI] shielding question
From: "Jim Brown" <jimbrown.enteract@rcn.com>
Reply-to: Jim Brown <jimbrown.enteract@rcn.com>
Date: Mon, 22 Dec 2003 16:34:35 -0600
List-post: <mailto:rfi@contesting.com>
The shielding enclosure of most electronics is a reasonable ground
reference. A 747 has no connection to earth, but the shielding on its
wiring works just fine. 

And even if that receiver had a 2-prong plug, the path from the
receiver to earth is likely to be some significant fraction of a
wavelength away from earth. If it happens to be some odd multiple of a
quarter wave at some frequency, it will look pretty much like an open
circuit at that frequency. 

The principal reason for that 3-prong plug is to provide a safety
ground for the equipment, both to prevent a shock hazard, and to
provide a return path so that current faults to blow a fuse. 

Jim K9YC

On Mon, 22 Dec 2003 17:10:23 -0500, George Johnson wrote:

>created the ground connection for the L-C filter because the receiver had 
>no ground reference (two prong plug) at all.

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