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.
http://cgi.ebay.com/Lemansind-50W-White-LED-FloodLight-Wall-WashLight-/270694205505?pt=US_Flashlights&hash=item3f06a1c841
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
levels.
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!
73
Craig
VK3HE
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