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Re: [RFI] Light fixtures

To: rfi@contesting.com
Subject: Re: [RFI] Light fixtures
From: Bob K6UJ <k6uj@pacbell.net>
Date: Fri, 1 Jul 2016 12:45:23 -0700
List-post: <rfi@contesting.com">mailto:rfi@contesting.com>
Dave,
You are not alone. I put in some LED strip lights under our kitchen cabinets. They should have their
own call sign they were making so much RF noise. :-)
I returned them and put in fluorescent lights.  Now no problem.

Bob
K6UJ





On 7/1/16 12:36 PM, Hare, Ed W1RFI wrote:
 From antenna modeling I have done, the decay of noise with distance depends on 
how the noise is being coupled on to conductors and how imbalanced those 
conductors are.

If noise is coupled onto wires in the common mode, noise will generally decay 
at a power rate of the inverse of the distance squared.

If noise is coupled onto well-balanced wiring in the differential mode, 
radiation will generally decay at much higher rates, as high as 1/D^3.

For differential-mode coupling onto poorly balanced wiring, the decay rate is 
somewhere between those two extremes.

Interestingly, the balance of wiring can vary as loads are changed.  One 
obvious change is what happens when a light fixture is switched. When the 
switch is closed, the balance of the electrical wiring at RF is fair, and most 
power is conducted to the load.  When the switch is opened, it opens only the 
hot lead, effectively adding a short piece of end-fed wire to the 
electrical-wiring transmission line, and emissions will increase by 10 dB or 
more.

-----Original Message-----
From: RFI [mailto:rfi-bounces@contesting.com] On Behalf Of Dave Cole
Sent: Wednesday, June 29, 2016 6:59 PM
To: rfi@contesting.com
Subject: Re: [RFI] Light fixtures

On Wed, 2016-06-29 at 20:38 +0000, Hare, Ed  W1RFI wrote:
Also, where do we draw the line?  There is a major difference in kind
between a ham that buys a device, installs it in his or her own home
and has S9 noise to an antenna close to the house, and S9 from a
device in a neighbor's home.
I never even thought about that...  I have a light I put up with in the Laundry 
Room, it is LED, noisy, (S9), and about 30 feet from one antenna, and maybe 100 
feet from the other...

I only hear it on the closer antenna...  Not even detectable on the far antenna.

--
73's, and thanks,
Dave (NK7Z)
For software/hardware reviews see:
http://www.nk7z.net

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