The first and most important step is to heavily filter all conductors
entering and leaving both units. This is important because all wires act
as antennas, efficiently radiating and receiving the interference -- it
doesn't matter how good the cabinet is if you have ways for interference
to get through it. Filtering can be simple or difficult depending on
what lines you're filtering, and doing a really good job requires
considerable skill and knowledge. For the tuner, you can't filter the
differential antenna current at the frequencies you want to receive, so
you'll have to put it far away and heavily filter the common mode current.

In addition to heavily filtering all conductors entering or leaving, you
need to enclose each unit in its own secure box. Any decent conductor
(e.g., copper, aluminum, or steel) will do for MF and above. The
important thing is that it can't have any holes or slots except small
ones, and even those will degrade the shielding. This means that all
seams have to be sealed with multiple screws or rivets and/or RF
gasketing material. Any large holes like one for a meter should be
covered with screen which is solidly connected all around its perimeter.

Those are just some of the basics. EMC is a challenging discipline, and
doing a really good job of isolation generally requires skill and
knowledge beyond that which most amateurs have.

Roy Lewallen, W7EL

ml wrote:
HI

I was wondering in general, how best to create some VERY effective
shielding between some equipment

for example, I wanted to stack my powersupply ontop of a tuner

while each are in metal enclousures and properly"" grounded i wanted
to go further


what is the best way?? would a thin sheet of lead (i'd encase in a
rubber coating) or a sheet of copper?


or would the only way be to say get some copper tape and wrap the unit?


thanks