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Re: [RFI] Cell Phone Charger Duracell made in China

To: svetanoff@earthlink.net
Subject: Re: [RFI] Cell Phone Charger Duracell made in China
From: Chuck Shinn <chuck.shinn@verizon.net>
Date: Tue, 04 Jan 2011 10:58:43 -0600
List-post: <rfi@contesting.com">mailto:rfi@contesting.com>
Thanks for the tips. A differential filter would be appropriate on this 
on on the input and perhaps by modification on the output side as well 
as CMC filtering, but it is leaving my premises on Thursday to entertain 
someone else at Texas A&M with my son. If he brings it back on break I 
will break it. Just for entertainment value:
It is a small and light weight little wall wart styled thing of the sort 
you find in Fry's electronics and perhaps Best Buy. It is labeled 
Duracell but made in China. It is far too light to have any filtering 
components inside for a charger capable of sourcing 700 ma. It is 
sealed.  It can be heard in a small AM radio (at both 2 Mhz and 10.1 Mhz 
) as loud hash with a pulse component. As previously stated both 7 and 
14 Mhz are clear. Frankly its not worth investing more money into it to 
make it palatable to me. I just wanted to give anyone reading a heads up 
on this JUNQUE with an American Label on it. Unfortunately, just one in 
a very long line of dirty accessories.

Best, Chas

On 1/4/2011 10:46 AM, Dale Svetanoff wrote:
> Chas,
> If ther unit is that "dirty", I have to wonder if this is one of those
> instances in which parts (used for EMI control) are being omitted from the
> production version of the item.  The only way to know for sure is to open
> it up and inspect the board.  On the other hand, FCC Part 15 radiated
> emission limits do not apply below 26 MHz, and they don't consider
> conducted emissions.  You might try powering the device via a high quality
> power line filter, BUT you would need to get one with serious attentuation
> down to 2 MHz.  Those are not real common.  The usual lower cost line
> filters are not effective that low in frequency.
> 73, Dale
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