[RFI] ARRL to FCC...

Hare, Ed W1RFI w1rfi at arrl.org
Tue Mar 25 16:04:41 EDT 2014


Dale, 

The ARRL Lab can also buy a "brute-force" filter for you to try, as these can be pretty pricey. We had the complainant in MD willing to try, but his neighbor stopped cooperating, then the ham moved.

Jim, et al, if there are any suggestions for brute-force filters to try, post them and I will buy them and have them at the ready.

Ed, W1RFI



-----Original Message-----
From: RFI [mailto:rfi-bounces at contesting.com] On Behalf Of Dale J.
Sent: Tuesday, March 25, 2014 4:01 PM
To: jim at audiosystemsgroup.com
Cc: rfi at contesting.com
Subject: Re: [RFI] ARRL to FCC...

Yes, I agree.  The outlet strip was a bad choice but all I had at the time to try.  I am going to make up a choke per your paper which I have and first chance I get I'll try it out on their set.  I use #31 mix snap-on's all over the shack, but I'll need a big one for this project.

73
Dale, k9vuj


On 25, Mar 2014, at 14:34, Jim Brown <jim at audiosystemsgroup.com> wrote:

> 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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