[RFI] Switch mode lamp noise
msole at loxinfo.co.th
Thu Feb 6 21:32:14 EST 2003
When we moved into our house I had some nice halogen spot lamps fitted
in the shack. Didn't realise at the time that these things have a
switching supply to produce the 12 volts for the bulb. With only a
single one fitted to the track it produces enough rubbish to wipe out
everything from top band through ten. Antennas are outside 100 foot away
fed with coax.
They are a very simple design, recified household supply powers an
oscillator which is then transformed down to 12 volts. Scope shows a
nice 11KHz sqare wave. These things are two wire only, no ground.
Is there anything I can do to get rid of the noise, short of either
replacing them or fitting a 20 amp DC supply in the attic?
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