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Re: [CQ-Contest] LED Lighting RFI

To: Contest List <cq-contest@contesting.com>
Subject: Re: [CQ-Contest] LED Lighting RFI
From: Mike Ritz <w7vo@comcast.net>
Date: Thu, 19 Oct 2017 21:13:26 +0000 (UTC)
List-post: <mailto:cq-contest@contesting.com>
I have a variety, but the one that I have easiest access to for checking was 
marked as "MaxLED by Maxlite, 800 lumens, 2700K, 9W". I could put the AM radio 
within a few inches of the lamp and there was no noticeable noise. That said, 
this is a more expensive dimmable LED bulb, and I did find out that the dimmer 
switch itself (the lamp is from IKEA), puts out quite a bit of noise unless the 
LED lamp is driven to full brightness. I guess this could be expected as it 
probably pulse width modulates the lamp to provide the dimming. 

Around my radio benches are pretty quiet, as all my supplies for 12V equipment 
are transformer units, mostly from the local Goodwill store (generally $2.99 
each!). A lot of hash is noticeable around the Comcast router in adjoining 
room, but my question is; How far out does the noise have to go to be a 
problem? If I only can detect the noise with my AM radio at 6 inches to 1 foot 
or so from the object, is that quiet enough, or is ANY noise emitted to any 
distance unacceptable? How far do we need to take it, and how much noise is 


----- Original Message -----

From: "W3IDT Bob" <w3idt@comcast.net> 
To: "Mike Ritz" <w7vo@comcast.net> 
Sent: Thursday, October 19, 2017 9:29:29 AM 
Subject: Re: [CQ-Contest] LED Lighting RFI 


You said, "Surprisingly, the LED bulbs I have in all my lighting 
fixtures have been quiet." 

Do you know what brand? 


Bob, w3idt 

. Robert F. Teitel, W3IDT . 
. . 
. W3IDT@arrl.net . 
. W3IDT@comcast.net . 

On 10/18/2017 10:41 AM, Mike Ritz wrote: 
> I just bought a 70's vintage nice quality transistor AM radio at at thrift 
> store, and have been taking it around my house to listen for noise. 
> Surprisingly, the LED bulbs I have in all my lighting fixtures have been 
> quiet. My DirecTV box is VERY noisy, as is my Accurite weather station. My 
> 2009 vintage Samsung LED TV also emits a lot of hash, but can only be heard 
> when I put the radio right up to the television. Fortunately for me, my shack 
> is in my metal shop, (on a separate power feed), but of course, my antennas 
> are not. Now that I have this "tool" I am going to take a hard look a every 
> piece of electronic stuff I own and evaluate the noise levels. 
> 73; 
> Mike 
> W7VO 
> ----- Original Message ----- 
> From: wigi@kl0r.com 
> To: "K9MA" <k9ma@sdellington.us> 
> Cc: cq-contest@contesting.com 
> Sent: Tuesday, October 17, 2017 9:56:16 PM 
> Subject: Re: [CQ-Contest] LED Lighting RFI 
> Thanks for the post, Scott... We have a pernicious noise problem from power 
> supplies at KL7RA... from the DirectTV boxes. We can take them offline, but 
> it would prevent ops from watching "The Young and The Restless" reruns on the 
> Soaps channel. I am curious if there are any suggestions for quiet switching 
> supplies for the random home electronics?? 
> Wigi 
> -----Original Message----- 
> From: CQ-Contest [mailto:cq-contest-bounces@contesting.com] On Behalf Of K9MA 
> Sent: Friday, October 13, 2017 11:38 AM 
> To: CQ Contest <cq-contest@contesting.com> 
> Subject: [CQ-Contest] LED Lighting RFI 
> Last winter, I tracked down some bad RFI to a neighbor's LED lighting system. 
> Replacing the power supply completely eliminated the interference. I just 
> bought a similar one for my own home and tested it for RFI, finding none at 
> all from 160 through 20 meters. Antennas were less than 25 meters from the 
> power supply and lights. I have plenty of other noise in this urban location, 
> so there might be noticeable RFI in a quieter location, but this power supply 
> is certainly a lot quieter than many of the others in the neighborhood. 
> I can recommend the Armacost power supplies manufactured by MOX Lighting, 
> models MD24W12VA and MD45W12VA. The 60 W version from LTF Technologies was 
> the bad one, but Armacost told me they were dropping that vendor, and the 
> MD60W12VA Armacost sells now appears to be made by MOX, though I haven't 
> tested it. By all means, stay away from anything manufactured by LTF 
> Technologies. 
> It appears it really IS possible to build low-cost switching supplies that 
> don't generate enormous amounts of RFI. 
> 73, 
> Scott K9MA 


. Robert F. Teitel, W3IDT . 
. . 
. W3IDT@arrl.net . 
. W3IDT@comcast.net . 

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