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[RFI] LED Floodlight warning!!

To: rfi@contesting.com
Subject: [RFI] LED Floodlight warning!!
From: Craig <vk3he@yahoo.com>
Date: Sun, 23 Jan 2011 03:46:25 -0800 (PST)
List-post: <rfi@contesting.com">mailto:rfi@contesting.com>
Hi All

I  recently purchased this   new LED floodlight which has turned into a RFI 
nightmare. I just want to warn other hams about the huge amount of interference 
that these lights cause.

My warning might also help those looking for interference sources around their 
neighborhood. LED floodlights are a disaster as big as bad plasma TV sets 
because the QRM level is so intense.

These light are becoming popular because they can save you  a lot of money when 
compared  to running a normal 500 watt floodlight.

I purchased several of these LED lights from various Ebay sellers. They all 
seem to originate from the same factory. They have   ratings from 10 to 50 
watts. These lights are the ones that use a huge  large LED CHIP  rather than 
discreet individual LEDs

Here is a link for one on Ebay, if it looks like this light avoid it.


A generic search for "LED floodlight" will show the many seller listings for 
these lights.

These light cause S9+20db hash right across the HF spectrum. Its the worst case 
of switch mode power supply noise that I have ever encountered. What also 
amazes me is the strength of this hash that could be detected from a long 
distance away, upto 1km away!

I emailed the supplier,  and  he  advised me that he has paperwork which 
certifies the lights with  a C tick compliance. The paperwork is obviously 
fraudulent or he is just telling lies. Most of the  goods from China have  fake 
EMC compliance documents and certification ..

When I opened the light, it had a small switch mode power supply module. This 
module does not appear to have any mains filter or other output filtering. The 
light is well shielded since the whole assembly is cast  aluminum. The power 
supply module is well shielded, hence the surprise at the rather high  noise 

 I added a IEC filter which did nothing to reduce the noise level. I added 2 X 
Fair-rite FT240-31 ring cores on the power supply lead and this did not help 
either. I added 2  X #31  material cores onto the DC output and this did help, 
however the noise was still shocking.

 I am going to try some capacitor bypassing and perhaps a professional  DC 
filter. So far the signs are not encouraging. The noise is still very intense. 
If I dont have luck I will just throw these lights in the bin.

I have these lights in 10 20 and 50 watts and they all have the same 
interference levels. Its a real shock to turn on my  SDR receiver and see the 
waterfall go red(5/9+) from 1mhz to 30mhz! 

Anyway avoid these lights like the  plague! 


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