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Re: [RFI] Phone

To: rfi@contesting.com
Subject: Re: [RFI] Phone
From: Jim Brown <jim@audiosystemsgroup.com>
Reply-to: jim@audiosystemsgroup.com
Date: Wed, 15 Dec 2010 08:38:27 -0800
List-post: <rfi@contesting.com">mailto:rfi@contesting.com>
On 12/15/2010 8:23 AM, rick darwicki wrote:
> I have large multiturn LF and HF material chokes on my old portable phone 
> line, right at the phone.

What's a portable phone line?  Do you mean a radio-based wireless 
extension of your wired phone line?  If this is what you're describing, 
I'd guess that your body is acting as an antenna to couple 10M RF into 
the portable handset (which is really a UHF radio transceiver), and the 
poorly designed circuits in that portable handset are detecting the RF.  
When you grab the ferrite choke with one hand, the RF current carried by 
your body is being diverted away from the portable handset to the 
telephone wiring.

The above is a WAG. :)  But think about it -- when you use a 2M talkie, 
your body is acting as the return for antenna current through the rubber 
duck, just like radials are acting like the return for antenna current 
with an HF vertical antenna, or the car body acts as a return for 
antenna current with a mobile antenna.

73, Jim K9YC
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