Alas, on the wretched hour of Fri, 02 Feb 2007 21:52:54 -0800 tack thusly
proclaimed:

snip

I believe that I've read that the distance from metallic objects
should, at a bare minimum, be at least 1/2 the coil diameter. So that
means 2 times minimum, giving 1/2 of coil diameter around the sides.
3 would be much better. Aluminum is good shielding material; onlt
thing better would be copper (or silver).

Guess I came up with a rather cheap alternative then.

Think newspaper, or any other kind of paper, would be good filling
material to isolate the transformer from the aluminum can?

--
Nos