I have one of those "touch lamps". As you touch the metal shaft, it cycles though: off, dim, medium, fully on using a Triac.
The unit kicks out terrible radio interference, as expected this is worst at dim and medium, though off and fully on are not completely clear.
It's worst around 6MHz (49m short wave), continuing upto 30MHz. The top aof medium wave (1.6MHz) is also pretty bad. Lower medium wave and long wave are somewhat better. It sounds like a buzzing noise.
I don't really know if the interference is conducted or radiated.
The unit is marked CE, so I would have expected care in the design to smooth out sharp switching edges and corners to avoid this, but not so.
I have some mains voltage rated capacitors (only 1000pF which is a bit low), and have tried connecteing across the 240VAC supply at live to neutral, live to ground, neutral to ground. None made any difference.
I've not yet tried capacitors across the light bulb, but will do.
Anybody on here had a similar experience and fixed / reduced the problem.
Thanks,
Fred