[Elecraft] Noise from LEDs

[Ka9p at aol.com]

...and I'd add the cheap Chinese LED's are a serious issue.
 
Our garage door opener was randomly working during and after a recent  
kitchen remodel.
 
After befriending Google, used the KX3 with a snoop loop, and  found that 
switching on either of 2 banks of new LED's generated enough RF  to swamp the 
garage door opener receiver about 15 feet away.
 
At least in our case the KX3 and loop did a good job of identifying which  
LED fixtures were the offending culprits, but finding a listing of good vs.  
bad brands remains difficult, if anyone has seen one would love to know...
 
73 Scott ka9p

 
 
In a message dated 2/2/2016 8:30:33 A.M. Central Standard Time,  
w0eb at cox.net writes:

I  don't usually chime in on these threads, but not all LED's are  
culprits.  I had originally replaced all the incandescent bulbs in my  
house with the compact fluorescent (CFL) type.  My noise floor went  up a 
couple of dB when any of them were on, so after a couple of those so  
called "5000 hour" Chinese CFL's actually burned up (yes, smoke, fire  
and flames) I bit the bullet and replaced all the fluorescent lights in  
the house with LED's, including some ceiling fixtures that used 2 and 4  
foot tubes.  Even though I don't have any "light dimmers" in the  house, 
I bought the "dimmable" LED 60 and 75 watt equivalents and now my  noise 
when they on is exactly the same as when they are all off.   Getting rid 
of the CFL's and doing to the LED's dropped my noise floor to  whatever 
the atmospheric (plus whatever the neighbors generate) noise  floor is.

Sure glad those CFL's tried to burn down my house as it  caused me to get 
rid of them.  I was able to hear and work the South  Georgia VP8SGI 
station on 15 meters and he was only maybe S1 here.   Bad propagation to 
that part of the world from Kansas even with 500 watts  and a beam so I 
missed the South Sandwich part.  Never heard them  except on 30 meters 
and my antenna favors East/West and I swear some of  the people that 
worked them on 30 were so strong here that HAD to be using  more than the 
legal power limit on 30.

Jim -  W0EB
>
>
>
>On Mon, 2016-02-01 at 22:48 -0500,  johnpierce wrote:
>>  My kitchen, under cabinet lights, are  LEDs.  With those lights turned
>>  on my
>>   noise floor changes from -128db to -102db.  If the circuit is  changed
>>  to a
>>  different phase the noise  improves by 6db.  All of this at 7mhz and
>>   other
>>  higher bands.  Needless to say the AM broadcast  band is highly
>>  affected by
>>  the  LEDs.
>>
>>
>>
>>  Placing a type 31  core with three turn of the AC line feeding the LED
>>   power
>>  supply and a clamp on 31 core on the LED side of the  power supply
>>  provides
>>  no  improvement!  I do not have an oscilloscope to look at  the
>>  waveforms.
>>  But given what I have done,  why is there no improvement?  I was
>>   following
>>  recommendations provided by  NK7Z.
>>
>>


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