[TenTec] [] Running a Century 21 on external 12V power

[Stuart Rohre]

OK, the reason TT used aluminum is they had an aluminum box plant, and 
lots of aluminum.

Aluminum is great for shielding electric fields, while steel and mumetal 
shield better for magnetic fields which is the principal field affecting 
the direct conversion receivers.

So steel would be up a notch in shielding magnetic field, and Mu Metal 
the best of all three.

Stuart Rohre
K5KVH