[CQ-Contest] LED Lighting RFI

[Mike Ritz]

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 acceptable? 

73; 
Mike 
W7VO 

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

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

Mike, 

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

Do you know what brand? 

Thanks. 

Bob, w3idt 
-- 

............................. 
. Robert F. Teitel, W3IDT . 
. . 
. W3IDT at arrl.net . 
. W3IDT at 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 at kl0r.com 
> To: "K9MA" <k9ma at sdellington.us> 
> Cc: cq-contest at 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 at contesting.com] On Behalf Of K9MA 
> Sent: Friday, October 13, 2017 11:38 AM 
> To: CQ Contest <cq-contest at 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 at arrl.net . 
. W3IDT at comcast.net . 
.............................