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Re: [RFI] Common Mode Line Filter

To: rfi@contesting.com
Subject: Re: [RFI] Common Mode Line Filter
From: Jim Brown <jim@audiosystemsgroup.com>
Reply-to: jim@audiosystemsgroup.com
Date: Sun, 10 Aug 2014 22:15:28 -0700
List-post: <rfi@contesting.com">mailto:rfi@contesting.com>
On 8/10/2014 10:03 PM, David Cole wrote:
Which forces me to ask...  What does the power company call common mode?

The voltage between neutral and green.

Thanks to a "Pin One-Like Problem" in most equipment, common mode often trash leaves equipment on the green wire, which radiates it. The Green wire SHOULD be bonded to the chassis at the point of entry, but it often is not. Instead, it goes to the circuit board, and may eventually find the chassis. Sometimes it fails to hit the chassis because paint is in the way. This is "The Pin One Problem."

In virtually all commercial line filters, the green wire bypasses the filter, so the filter does nothing to kill common mode current.

73, Jim K9YC
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