This is a VERY VERY VERY common problem -- yet another dirty switching
power supply.
The easiest cure is to replace the power supply with a linear supply.
First, you must measure the voltage and current. Then look for a linear
supply having the same voltage and current rating, break the cable
between the supply and the lights, and splice in your linear supply.
Depending on the current you need, you may find a vintage wall wart that
provides sufficient current.
A variation of this solution if the supply can't supply the current is
to add a suitable lead-acid battery that you can trickle charge from the
linear wall wart.
It is often possible to kill the noise with a suitable ferrite choke.
Study k9yc.com/RFI-Ham.pdf
You will need a choke on both the AC and low voltage sides of the noisy
supply.
73, Jim K9YC
On Mon,9/29/2014 10:25 AM, Don Kirk wrote:
Late last week I encountered interference on 160 meters which was repeating
at 41 khz intervals, and this morning I was able to track the problem down
to low voltage bookcase lights at my neighbors home which is 430 feet
away. I created a website to document this case which includes a link to a
youtube video that contains receive audio of the noise, and my simple
website URL is http://sites.google.com/site/bookcaselightsrfi/
The signal was S9 on 160 meters (approximately 15 dB above my noise floor
when using a 500 hz receive filter), and it could be heard up into the 80
meter band.
We (my neighbor and I) will now dig into his low voltage lighting system to
see what we can do to eliminate the interference.
Just FYI,
Don Kirk (wd8dsb)
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