summary: power supply and chassis

[Haible Juergen]

	>(some MHz).  The railway is r=20m away, so there is strong 16,333
Hz
	>(yes sixteen and a third) and also railway radio interference. 

Yes. I forgot to say that I don't live in a very RF stressed area. Never
taken my stuff out. So yours is surely a good advice.

BTW, I think they chose such a low frequency for the railway in order to
build longer railroads without a break in the "power supply line".
If you're building it long enough you will get a resonance across the line
even at 50Hz - and imagine the "sound" of a filter resonance with
that kind of power involved (;->). At 16.333 Hz they can build the tracks 
3 times as long.

JH.