[RFI] ARRL to FCC...

[Hare, Ed W1RFI]

Hi, Jim,

What I am suspecting is that we may need to install the following filters:

Differntial-mode AC filter
Common-mode choke on AC mains
Common-mode choke on incoming coaxial cable
Common-mode choke on any other long leads to the TV screen

Jim, is your choke cookbook on line? I want to make sure that ARRL links to it, on a number of our pages, actually. :-)

73,
Ed, W1RFI



-----Original Message-----
From: RFI [mailto:rfi-bounces at contesting.com] On Behalf Of Jim Brown
Sent: Tuesday, March 25, 2014 3:34 PM
To: rfi at contesting.com
Subject: Re: [RFI] ARRL to FCC...

On 3/25/2014 11:49 AM, Dale J. wrote:
> Once when I had access to the TV, I tried one of those outlet strips 
> with filtering and it made no difference

I would not expect it to. They only affect the differential mode signal. 
As Ed has noted, the signal can be radiated common mode on the power cable, on an antenna (or CATV) cable, and even on cables connected to an A/V rig. If it's common mode, you need serious mutli-turn ferrite chokes, not "filters." Below 7 MHz, Fair-Rite #31 is the weapon of choice. Above 10 MHz, #31 is still quite effective, but #43 is slightly better. See my choke cookbook for some winding guidelines. Luckily, I've yet to encounter a plasma set, but there was a report, I think on this reflector, from a ham who had pretty good suppression with a choke on the power cable.

It's also possible for RFI to be radiated from wiring internal to the set, and chokes won't help with that mechanism.

73, Jim K9YC
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