Letter Re: Expedient Faraday Cage EMP Protection

Sunday, Sep 17, 2006

Mr Rawles,
First...this is an excellent site and, on equal footing, so is your book "Patriots". In my opinion so much so that in the course of habitually re-reading it I am wearing the book out.
In regards to EMP protection: an old refrigerator, chest freezer, unused oven, or for that matter, a metal utility cabinet etc. will work. These appliances will allow the storage of more than a few "delicate" and sensitive electronic devices. Having a redundant radio collection is advisable. These devices will function well as long as all six sides are metal, are electrically connected (a few nuts, bolts, washers and some 14-12 gauge wire will work as long as the paint/enamel has been scraped away to the bare metal where-ever the screws and wire contact the factory finished surfaces), has RF gaskets at all door and other openings and has grounding straps connected using the shortest wire run possible and the largest wire diameter available. Without a ground connection the shield may act more as an antenna than a shield and inadvertently destroy what is intended on being protected.
RF gaskets can be fashioned from fine phosphor bronze mesh polished and soldered into a narrow diameter tube or the ground braid component of any of the higher grade coax wire that has 95% braid coverage or better. After carefully removing the outer jacket of the coax the braid can be extracted. Solder a length of copper wire to one "wall" for the braid cylinder being careful not to occlude the braid opening. Depending on the diameter of the wire selected (RG 58, RG 8 etc.) literally any rigid foam, foam rubber or rubber material of near equal diameter can be inserted into the braid. A length of a child's "Wacky Noodle" toy (thin gauge) will work although a soft rubber material is preferable albeit a tad harder to locate. The ground braid will function in the same manner as a Chinese finger...it will close up when stretched. Solder the ends together after the rubber core is inserted and cut to the appropriate length. Connect the previously connected wire to the item being used as a Faraday cage. Be certain that all mating surfaces are void of any type of finish. Auto body sanding paper works well for the task. The gasket can be riveted in place or an electrically conductive adhesive can be used although far more expensive to purchase. Be certain to ground the cage.
Older receiver/transceivers with discrete rather than flat pack electronics (high I.C. chip populations) are good backups and, in the C.B. class, less costly. As a note the newer radios have very static sensitive and EMF sensitive components in them and as such require a higher level of protection. Lowe's, Home Depot and other building supply outlets sell self adhesive copper foil (a type of flashing material) that is wonderful for EMF shielding and it is solderable therefore affording complete protection if need be as long as a ground wire is connected and all seams are sealed (soldered works well). The foil is thick enough to withstand abuse and yet thin enough to be cut with scissors.
Second...do you or any of your esteemed readers know of any studies examining the results of high power EMF and their effects on solar panels? Being that the inherent design of photovoltaic arrays are such
that the interconnection on and between the individual cells forms a grid whereby the potential exists for a large EMF field to create an extraneous voltage in the panel thereby causing all sorts of damage to anything connected to it/them. I have done some search engine queries and contacted a few manufactures but have not gotten any results to date. - Joe in Tennessee


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