Table Of Content

AVOIDING EMP DAMAGE Electwomagnetic Pulse (EMP}is only a zeal threat from a nuclear explosion in space. Tis, standard miftacy suategy to use such explosions prior to any nuclear attack, sc we need lo expect them. “The severity of dhe poleal Uamnage is not fully documented at this time, but some damage definitely will occut, Most of alf I expect all normal utility prwer io be damaged severely — blowing out all major transformers and relays. Here ae some things ‘hat you should know fo ensure that cetical electronic cquipment is nat damaged. 1, Asegular lightning arrestor reacts too slowly tn protect sgzinst EMP. You need one (hat reacts within 2 nanoseconds. Look on the specifications labels an any power strip you buy. Some will match this standard, The Recommended Eyuipment and Sources section willis several manufacturers hat have equipment you can igstall on you: incoming powerlines to add protection to your whole house, W's no| cheap — several hundred dollars. These ute will iver amy poscer surge af high volsage that ‘comes dawn your lines and shunt them wo a large grounding rod. This shunt is special switch which goes inve opersticn when the voliage spike hits, Ir does not ground normal vollage (or you would never have any power). 2. All grounded appliances in your home Ibat are UNPLUGGED tay be partly prowected since the metal chassis will ubsorb some of te EMP and fced ito ground Gf grounded separately and not through the plug) Bul the plug cord lying owt im the ‘pen sill pus your equipment in jeopardy. ‘The plug cord will actfike an antenna, picking op all BM®. 3. Portable atectrical equipment run by battery should be stored in a meal box, like a military ammo ean with a tight scal. This is the cheapest way to make sure your sadios will work when you need them, The EMP cannot penetrate a closed ractal bor. 4. Use stectshiclding around senmive operating equipment with coils, making sure itis well grounced. In dry climates, grounding rods should have water {mized with some Epsom salts) poured down and around where they arc driven into the earth every six ‘months ora year to make sure they make good conductivity withthe cart, 5. Disconnect large radio antennas at the unit unless setually in-use. During a nuclear ‘war, connect them only briefly to listen for news. Shelters ina stel-reiaforced basement room will have some steenuating effects on electromagnetic waves, bul MOL enough © roy on. A quick und diy tat ofa shltr's atenvating capability ts 69 fum on an FM recsiver and nce how well tpicks up local FM satons within the Shelter. Any significant reception sbilty of FM signals means you ate dot protected tthe portable radio (while tuted on with the volume up high) io a rbetal box and listen to the difference, Itshould snp broadeasing. GROUNDING 4 will cover house witing gronnding in the the Mester Electrical System chapter, but will also cove: grounding of equipment in this chapter so thavit will give you the complete details on shelter equipment problems. Proper grtwnding i the most critical aspect of both fighming and FMP protection. Grounding provides a path for electrical currents to travel (ward the earth, which is tho ultimate destination of all electrical charges. Lightning has both high voltage and high current, EMP hs low current but extremely high voltagc, and more importantly, an exemely hich ond sharp voltage spike, ‘This, instantaneous rise time in the voltage spike for EMP is the key t0 why EMP is 50 dangerous 4 electronic components. The EMP voltage spike coming down the line can ‘wavel through most lightning protectors before they have a cance to react. PolyPhaser’s book, The “Grounds” for Lighming and EMP Protection, is probably the best on the market on grounding solutions. Iris easy to understand and faily nontechnical ‘Voltage and current spikes are surges of electricity that cxoced the capacity of dhe <loctrical components in your equipment. The most imporiant thing todo isto ktep these Sutges ftom entering your home. This is difticutt to de when you have things like antennas whose very job isto atiract the tiniest of electrical signals, If we are going to try toprotect sensitive antennas ducing operations, that requites a highly sophisticated device that can distinguish berween small signals and these big surges and then shut down the path before the serge can eater. This is very dificult. ‘You can see why itis much easier to protect equigment by disconnecting it from the feedlines and power sources, But it docs help t provide a proper equipment ground and add protective devices to your instalation. When lighming stnkes, i wil always ty 10 find the shortest electrical path to ground, Unless you discoancet yout siation equiprient, your antennss wil be providing that best path to ground. To prevent lightning from wsiog {your feedlines it i best ta disconnect them where the feedlice fram the anterta connects tn your through-the-wall connectors. These eonmectors from outside atc attached to surge protectors bolted toa big copper plate which has is awn ground rod and is interconnected To other ground rou, So if you disconnect from this contecror on the copper plate, the surge wil yo tu ground and not to your equipment. If you disconnect your coax and leave it yiag on the floor, close to where itis connected to your rads, Fightaing can jump a Bap of several feet to the eesipment, The fightaing has already saveled a tong way ‘cough the ait and a few mare feet of atmasphorc won't stop what we cal “side flash.” Proper grounding is critical to Lighming and EMP protection. Lightning and EMP eontsin pulses in a wide range of frequencies, so you must provide a low impedance palbway that is eapable of handling noany different froquencies as well as high corrent. (One ground rod is usually noc enough. If you only vse ome, you will have tb run alot nf Jug, thick cables to comic all quipment 10 mis single source. These long cables provide aumerous opportunlies to side flush w other equipiment nearby. Ground 1oJs should be made opt of solid copper, copper-clad steel, hot-dipped galvanized steel, or stainless steel. They usually comme in lengths of at leu, 8 feet and ate 1/2 inch, around, ‘Copper strapping comes in a aumber of izes, bura strap 1-3/2 inches wide and 0.051- inch thick isthe mininaum recommended for ground connections. A copper strap makes ‘vheitertightning and RF ground than a wire because of its lower inductance. The wove or braided kiss are most effective and exsy to work wich, Bate copper re should be used for busied ground wires —it is less subject to coresion than soven cba, The size you should use depends on the length othe un, T usually vse oF #6 ww (American Wire Gauge). Antenna Towers ‘Your antenna and cower ace the prime poinis of surge entrance, so proper tower rounding is importaat, The goal is o extablish muldiple paths to the earth ground atthe forwer so thatthe strike energy is divided and dissipated. To establish multiple curent paths on a lower, connect each of the tower legs and all of dhe metal guy wires to sopanately-driven ground rods. The ground rods must not be closer than 6 feet from cach ciles. Bond the lower ground rds ingether with a #6 awwy or lager copper bonding, ‘conductor (forming 4 “fing” around the tower base). In addition, connect a co comluctor befivecn the 1owe: “ring” ground und the buikhead pane! (that big copper or iuminuma plate) at the emerance to your radiv shack in the howe, All connections should be made using connectors and fitings approved for grounding applications. Use bolt or ‘crimp connectors but not solder alone. Solder can melt when lightning strikes. I wll use itthough if | also have a clamping comnoctor. Thave found thatthe wires don’t corrode under the clamps if soldered frst. [All grounding rods and wites around the home ueed to be connected electrically. This includes Tightaing rods, your electrical service ground from the utiliies, your telepheme, antenaa system grounds, and undesgrouad metal piping. Ground rods used for lightning protection or enteanoe-panel grounding must be separate ard spaced at least 6 feet from the electrical service or other utility ground so side flashes don’t oocor. ‘The purpose of ‘connecting all grounds is tn make sure the ealite system stays atthe same voltage “potential.” Ifyou had a lot af separately-grounded equipnient, one partion would have Alfferentclectrival chasge than another duting a surge and electricity could are from on grouré to another. ‘On antennas, gronnd the shield of the cable atthe top of the tower as well as atthe bottom, Several companies offer grounding blocks that make-multiple-ground ‘connections easier. See tre Recommended Equipment and Sources section Feedlines and Bulkheads ‘The feedine should alo be grounded just before it enters the shack ou a large grounded ‘copper plate as previously described. Fevuline lightning arrestors ate avaiable for both ‘coax cable and balanced line. Most ofthe balanced line arrestors use a sinuple spatk gap arrangement, but a balanced-line impulse suppresser is also available from several commpanis. ‘Arresiors for coazial cable also come in several types. DIC blocking-type arrestors have a fixed frequency range and must be selected for 2 specific application. You will uso Sifferent types fos snteanas of different frequencies and different ones for solar panels as ‘well, ‘Theit mein advantage is that they present 2 high-impedance path tothe frequencies, ‘oud in lighaning (less than 1 MiEi2) while offcring a low impedance to. signals cteated by ‘Yout ragio, “This is very important so that the vadio signals get through and the surges do aot, Artesiogs that have DC'continuty (the gas tube and spark gap types) ere broadband and ati be wed over a wider frequency range of antennas than the DC-blocking types. In installations where the coax is used to supply voltages toa remote device (such as a masi- ‘mounted preamp or rcmote coax switch), die DC continully-type arrestor faust be used, ‘Whether you use balanced line or coms. areators, they should be mouated atthe entry pint fo your shack—on what han) radio people call &“bullshead.” tnetall 2 1/8-inch hick ‘opper or aluminum sheeton the wall of your herue where your radios ate. Insiall a separate ground ced for this pane! and connect itt the Bulkdead with a short, copper sirap. Also, bond this ground rod to the rest af te ground system, ‘Then mount all Droective surge anrestors, antenne switches and relay disconnects on the outside wall of ths bullchead. This macs sure they are all comneutat to a big grout tod so that surges ‘won't enter Ube house, Since disconnocting the equipment is te best protection, itis mote convenient to installa feedline disconect setch rather than uascrewing all yaur antenna connections every Sexe (which wears them out). If you use a coaxidl feedline, you can use a manal, 2ulse position coax switch, a remole odax switch nw an in-line coastal relay. ‘Surge Protectors (One atea often neglected is powerline protection. inexpensive multi-cutlet tips usually coffer litle or no protection against surges or transients unless the power stripe are heavy duty and have quick reaction times. Check the label to make gure they react in less hare ‘Wo nanoseconds. Power line protectors use several diferent protection schemes, each of ‘which solves a different power-tine problem. Iarush eurtent limiters keep the input ‘current fo the equipment’s power supply from exceeding a fixed level. Transieat, suppressers (usually semiconductor-fype devices) absoth voltage spikes that could ‘damage sersitive digital IC's. Surge suppressers limit the input waltage oa tho line cgay a clamping effea) to prevent damage. To protect your equipment against by lighining-induced voliagesarges onthe AC line, woplug the power fife Yell socket. Don’t depeod on th builtin switch or wall-otlt switch. A paiby Sirite can induce voltage surges that wil easly jump the gap and averioad the pfoiective circolts.