>
> We discovered that the boxes were actually designed to store electronic
> components. There are black ones and red ones. The black ones were designed
> to be conductive to prevent eletrostatic charge problems with sensitive
> components. We checked the red ones and found that they had the normal
> insulating properties of plastic.
It's not only boxes.
I built a resonant transformer arrangement to couple 4MHz ultrasound signals
onto my rotating Ph.D. experiment:
http://n3ox.net/files/us_ring.jpg
The setup is essentially a pair of magnetic loop antennas tightly coupled
together. I discovered (fortunately sooner rather than later) that the
black rubber on the clamps that hold the lower ring to the fiberglass disc
in the picture was conductive.
Not a problem as shown there, but originally there were two clamps back to
back holding the ends of the lower ring, with probably just a few tens of
ohms between them. They're clearly designed to be static dissipative.
Fortunately, this wasn't a high power system and I found the problem
quickly, but I've learned my lesson about not assuming good dielectric
properties of all polymers ;-)
73,
Dan
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