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Re: [RFI] "No RFI" LED bulbs

To: rfi@contesting.com
Subject: Re: [RFI] "No RFI" LED bulbs
From: Kim Elmore <cw_de_n5op@sbcglobal.net>
Date: Wed, 16 Aug 2017 19:17:10 -0500
List-post: <mailto:rfi@contesting.com>
This interesting.

I've been switching o LED Christmas lights and was originally worried about RFI. I"m not certain how these work: Some provide FWB rectification while others provide only have-wave rectification. But, it's obvious that these don;t have a built-in PS. As far as I can tell, these things are RF-silent. I hear no change at all when I turn them on.

LED light bulbs are different because they have their own switching PS inside. I've used mainly Phillips, a few Cree and couple of no-names and, so far, haven't heard a thing form them. I've also replaced fluorescent tubes with LED equivalents and they're also quiet (both the kind that requires wiring around the ballast and the kind that will use a SS ballast). The same goes with CFLs. Sounds like I should thank my lucky stars!

Kim N5OP

On 8/15/2017 6:25 PM, Jim Brown wrote:
I suspect the RFI problem is caused by a poor quality power supply, or the use of AC to drive the LED directly. I've used a lot of the LED strips that Wired Communications sells at hamfests, mostly in the western US. I use five of them to light my shack, powering them from the 12V battery that is float-charged from a linearly supply.

Last month, I mounted two strips on a shelf to light the area around my computer desk, and, by accident, grabbed a 12VAC wall wart (in other words, just a transformer) to power them. The RF noise was VERY strong. Replaced the transformer with a 12VDC linear supply and the noise went away.

Of course, a switch-mode power supply would also generate noise.

73, Jim K9YC

On 8/15/2017 4:08 PM, Ken Winterling wrote:
I have also heard some reports that the fluorescent or LED bulbs in an
opener can cause trouble with electric car door locks.  Some folks had
difficulty locking/unlocking their car doors while the opener lights were

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Kim Elmore, Ph.D. (Adj. Assoc. Prof., OU School of Meteorology, CCM, PP SEL/MEL/Glider, N5OP, 2nd Class Radiotelegraph, GROL)

/"In theory there is no difference between theory and practice. But, in practice, there is." //– Attributed to many people; it’s so true that it doesn’t matter who said it./

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