Hi Don >>Because it's amplitude is time varying, aluminum or any other metal can >>provide an effective shield based on the skin effect principal (you just have >>to factor in the resistivity of the material and operating frequency to >>determine how thick the material must be to become an effective shield).<<
I think my preamplifier does not agree much with that. My PC LCD monitor screen was causing several noises I could hear on 160m and actually I could see them on the SDR waterfall. When I put the preamp inside a galvanized steel box all that crap coming from my PC and PC LCD monitor just vanished, the box was open in one side and not grounded. The preamp was inside a TIM PLATE BOX used for EME shield with feedthrough capacitor and chokes, but the steel galvanized box improved the shield a lot. 1.8 MHz is quite a different band. 73’s JC N4IS _________________ Topband Reflector Archives - http://www.contesting.com/_topband