[RFI] Switch mode lamp noise

[Martin Sole]

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?

73's
Martin, HS0ZED