Re: Blown by nearby transceiver #bitx40help

AC9NM - Jerry Ponko


Shielding, whether it's tin foil, copper, steel or aluminum forms what is called Faraday cage invented by Michael Faraday. When an outside electromagnetic (EM) wave encounters a Faraday cage its electric field induces a field in the cage which causes them to cancel. So the only requirement for the Faraday cage to work is that the material used be conductive. The cage doesn't have to be solid. For example, you may have seen power supplies, etc. covered by extruded aluminum or steel screening which will work as long as the holes are much smaller than a wavelength of the signal of interest. I myself use oak or birch enclosures lined with aluminum tape like the kind used for the joints of heating/cooling ducts. For the front panels I use 1/8" plexiglass with a laser printed sheet for panel markings. I'll have to post a photo someday of my BITX40 case as an example. I can't see myself paying the prices charged for aluminum or steel enclosures that cost as much as the BITX and you still have to do the cutouts for the controls and the panel markings.

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