[RFI] LED Bulbs

Mon Feb 10 19:30:59 EST 2014

Dale,

I totally agree with your statement about being "all over the ball park" with these devices.  Also, I do remember Mike's original postings several months ago about those nasty yard lights that belong to his neighbor.  I have been following this thread with interest and will now toss in my 2.5 cents' worth.

First, let's please keep in mind some basic EMC engineering and science issues with respect to the overall problem.  One big reason that the LED light systems seem to be all over the map on RFI is what seems to be a very wide variation in the implementation of the lamps themselves.  With the possible exception of a few LEDs in a flashlight that are directly powered by some AA or AAA cells, most illumination (as opposed to "indicating") LEDs are NOT powered by a simple DC supply, such as a battery.  There are MANY IC manufacturers out there who are selling controller chips to the lighting manufacturers.  I subscribe to several electronic industry trade rags, and I see ads for such chips constantly.  They ALL seem to have one thing in common:  NONE of the ICs (that I can recall) have any form of RFI/EMC control built into the chips themselves.  It is up to the end device designer (LED lighting manufacturer) to implement whatever EMC circuitry is required to meet the requirements of the countries in which they plan to sell end products.  

Next, there comes the major issue of just where are the driver electronics located?  Mike mentioned an iron core transformer powering that string of yard lights, so that almost certainly means that each individual lamp (or lamp fixture) contains a driver operating off that 12 VAC.  Thus, a true RFI nightmare because you have multiple sources all pumping junk down the wires back to the transformer.  No clean-up is needed at the transformer; all chokes and suppression techniques need to be employed at each individual lamp or lamp fixture.   That's truly bad news when you don't own the system.  OTOH, I can imagine that there are some systems out there with a single controller and a whole string of LEDs connected to it.  In that case, all suppression should take place at the controller so that the wires going out to the individual LED lamps don't become antennas.  The controller may also require suppression on its AC input.   

I was a bit surprised when the thread started discussing timers at one point.  OK, what sort of timers?  If they are strictly electro-mechanical, there is nothing in the timer to create noise other than bad contacts that could arc.  I have multiple electro-mechanical timers in use here for control of various CFL-equipped lamps.  No problems with RFI in the nearly 10 years these have been in use.   If the timer is electronic, then what is the control element?  If an electronic timer uses a relay, then only the contacts are an issue.  However, if an electronic timer uses a triac or SCR as the control element, then those devices can certainly be suspect, just as in photo-eye controllers for security lights.  If a switched (or controlled) load generates RFI when "on", then consider the load, as well as the timer or controller.  Again, this is not easy if you don't own the timer or load.  However, finding out just what your neighbor does have is critical to working out a possible solution to the RFI problem.

Clearly, successful RFI mitigation requires a lot of cooperation from the owner(s) of the offending device(s).  As has been mentioned many times on this reflector, speculation can end up wasting a lot of time.  For those hams unfortunate enough to have one or many RFI generators in close proximity, the fastest and surest way to figure out what you are up against is to secure the cooperation of the generator owners and then learn just what the device(s) in question is(are).  Then it is time to start thinking about what will be required to control the noise.  

73, Dale
WA9ENA                        

-----Original Message-----
>From: "Dale J." <dj2001x at comcast.net>
>Sent: Feb 10, 2014 5:44 PM
>To: Mike Ryan <mryan001 at tampabay.rr.com>
>Cc: rfi at contesting.com
>Subject: Re: [RFI] LED Bulbs
>
>Mike, I just got a reply from my contact at Menards.  He said that he's not seen this item at Menards.  Understand, it's a Lowes name brand.  It is possible this device is offered under many name brands.  We need to get the word out, watch out for this junk. I don't trust any of it unless I test it in my house.  The CFL bulbs have shown to be RFI ok here, I have them all over the house including two in my shack, they are quiet.  I have not tried any LED type lighting, but I know a ham who has some LED string lighting over his ham desk and says it's quiet, so all over the ball park with this stuff.  
>
>Thanks Mike
>
>73
>Dale, K9VUJ
>
>
>
>On 10, Feb 2014, at 16:40, Mike Ryan <mryan001 at tampabay.rr.com> wrote:
>
>> Dale, I think PORTFOLIO is Lowes brand.  The other stores may and most likely do have the same or similar product but under another name.  -Mike
>> 
>> -----Original Message----- From: Dale J.
>> Sent: Monday, February 10, 2014 4:40 PM
>> To: Mike Ryan
>> Cc: rfi at contesting.com
>> Subject: Re: [RFI] LED Bulbs
>> 
>> Noted.  I don't have a Lowes close by, but I do have a Home Depot and Menards.  Next time I'm there I will look for this product and perhaps drop some suggestions. I do know someone who works in the electrical department at Menards, he's a ham operator too.  I'll pass this information along to him, minus all the headers etc.
>> 
>> Thanks Mike.
>> 
>> 73
>> Dale, K9VUJ
>> 
>> 
>> 
>> On 10, Feb 2014, at 15:25, "Mike Ryan" <mryan001 at tampabay.rr.com> wrote:
>> 
>>> Dale, The brand name is PORTFOLIO, and sold around here at LOWES.   The model number is #0068062.  It is called a 'wall wash light'.  They are LED, low voltage 8w draw, with 420 lumens / 3000k.  The box says they are comparable to a 35w halogen floodlight.  Very, Very, nasty light fixture.
>>> -Mike
>>> 
>>> -----Original Message----- From: Dale J.
>>> Sent: Monday, February 10, 2014 3:06 PM
>>> To: Mike Ryan
>>> Cc: rfi at contesting.com
>>> Subject: Re: [RFI] LED Bulbs
>>> 
>>> I'd like to get the numbers of those lights.  Post them if you will, mfg too and where they are sold.
>>> 
>>> Tnx
>>> Dale, k9vuj
>>> 
>>> 
>>> 
>>> On 10, Feb 2014, at 13:36, Mike Ryan <mryan001 at tampabay.rr.com> wrote:
>>> 
>>>> Sorry Jim but the power supplies that these lights are connected to are not always the case. I mentioned in an earlier post here about some 50w LED lamps which use 12 vot AC, that's AC. The power supply is clean.  The BULBS have switching power supplies of some nature in them.  LOEWS has a line of exterior landscaping lights which will pretty much drive you QRT. My neighbor has 10 of these in his yard.  They are dirty from HF to at least 440mhz.  When his outdoor lights timer goes ON, I am OFF. I'd be happy to post info on these again should someone care.  - Mike
>>>> 
>>>> -----Original Message----- From: David C. Hallam
>>>> Sent: Monday, February 10, 2014 1:48 PM
>>>> To: rfi at contesting.com
>>>> Subject: Re: [RFI] LED Bulbs
>>>> 
>>>> I may have made an unwarranted conclusion, but I assumed the LED were
>>>> substituted for halogen without any other changes.  I will see if I can
>>>> get a clarification on that point.  Would a change in bulb types make
>>>> any difference in the RFI being generated?
>>>> 
>>>> David
>>>> KW4DH
>>>> 
>>>> On 2/10/2014 1:14 PM, Jim Brown wrote:
>>>>> On 2/10/2014 11:07 AM, Dave Cole wrote:
>>>>>> Who would have thought the LED's could radiate so far?
>>>>> 
>>>>> It's not the LEDs, it's the wires (antennas) connected to the switching power supply for the LEDs. This should come as no surprise to any ham --  switching power supplies are generators of RF trash, that puts RF current on those wires, and like any other antenna, those wires radiate the trash.
>>>>> 
>>>>> Thank you VERY much for posting details of part numbers and vendors for the bad products.
>>>>> 
>>>>> 73, Jim K9YC
>>>>> _______________________________________________