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Re: [RFI] Green Wire RFI

To: rfi@contesting.com
Subject: Re: [RFI] Green Wire RFI
From: Jim Brown <jim@audiosystemsgroup.com>
Reply-to: jim@audiosystemsgroup.com
Date: Sun, 15 Nov 2020 13:47:46 -0800
List-post: <mailto:rfi@contesting.com>
On 11/15/2020 1:16 PM, K9MA wrote:
If both ends of a winding of a common mode choke are connected together, it’s 
like a transformer with a shorted winding and the impedance of the other windings is 
reduced.

I suggest that you study my tutorial on how ferrite chokes work. k9yc.com/RFI-Ham.pdf An effective common mode choke is very lossy in the range where it operates, so transformer coupling through the core would be quite weak.

I’ll connect the green wire, but not through the choke.

NO! If all three conductors don't go through the choke as a single triplet winding, the choke adds inductance to the path that SHOULD blow the fuse, which delays the fuse blowing, which, as Frank observed, could make someone lose the use of themself.

And, since most power line RFI is ON the green wire, if it doesn't go through the choke, the choke won't do anything.

73, Jim K9YC
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