Alas, on the wretched hour of Sat, 03 Feb 2007 08:29:40 -0700 James M.
Potter thusly proclaimed:

There are two things to keep in mind when you put a coil in a can.

1. The inductance will decrease due to the reduced voulme for the
magnetic energy. This is the same effect as using a brass slug to
change teh inductance of a coil for VHF applications.
2. The losses will increase due to the induced currents in the walls
of the container.

The further away the walls are the lower the effect. The various rules
of thumb you hear are just the result of someone determining what is
acceptable.

Ah, so if there's lots of noise where I put my transformer I'm better off
taking a small hit to signal strength to still improve my s/n ratio, but
if there's little noise I'd just be canceling out the weakest signals...
Guess I'll have to try it with and without the can then to see if I've got
lots of noise here.

Thanks for the reply.

--
Nos