Understanding and protecting against EMP

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Here is some info on EMP I found. It is a long post. I would have included a URL, but this was obtained off of USENET, and I don't have a web-page to post it on. Here goes

    ELECTRO MAGNETIC PULSES    ------- -------- ------
Imagine a very bright flash in the sky! No one is hurt. But, your transistor
radio stops playing, your car won't start, the telephone doesn't ring,
lights stay off, and we find ourselves  in the stone age!
THE development of modern high-tech    semiconductor devices have paralleled
unsettled relations between the nations of the world with resulting technol-
ogical advances affecting the lives of  every citizen of North America.  Com-
munications have been made faster, automobiles more fuel-efficient and
maintenance-free, TV sets, video-tape   recorders, and virtually every other
piece of electronics equipment have been improved by the advent of the
semiconductor and its high-tech advancements.  The relationship between
nuclear weapons and the recent electronics advances may seem unclear, but
a nuclear attack on the North American continent could make that relationship
glaringly apparent.
ALL nuclear explosions produce electromagnetic pulses (EMP's) and the ensuing
induced voltages and currents produced in conductors ( wires and cables ) are
comparable in strength to the strongest of lightning bolts.  EMP's may reach 3
million volts and 10,000 amperes for a total of 30-billion watts of energy.
 The largest commercial radio stations in the U.S. and Canada radiate 50,000
watts, or approximately one-millionth that much power!  The major difference
between EMP's and lightning is that EMP's are induced simultaneously over
an entire wide area, while lightning occurs at a single location.
  Significance of the Problem  ------------ -- --- -------
THREE ten-megaton thermonuclear weapons detonated 250 miles ( 400 kilometers )
above the United States or Canada would produce EMP's strong enough to knock
out the entire electrical power grid of North America including the entire
civilian-telephone network, and just about every broadcast station.
 Virtually every piece of unprotected electronic equipment in the country
-- radios, TV sets, computers, electronic controls in homes, office build-
ings, factories, cars, airplanes, and instruments in hospitals -- would be
damaged, if not destroyed.  The pulses would also damage or destroy large
portions of the military command's control and communication (C3) system.
A chain reaction could be set in motion at nuclear power plants, due to elec-
tromagnetic pulses. Although it is a point that is frequently disputed, the
possibility exists that reactor core meltdowns might occur as a result of
EMP's.  The meltdowns would be a by-product of electronic control system
failure.  The control systems are used to monitor and control the processes at
the plants. The EMP's could cause the system to fail and result in partial or
complete loss of control over vital functions, causing subsequent melt-
downs.  We know that those nuclear plants are designed to be fail safe,
but has anyone considered the possibility of every circuit breaker in a
plant failing at the same instant?  Characteristics of EMP's
  --------------- -- -----
AT an altitude of 250 miles, the gamma rays produced in the first few nano-
seconds ( billionths-of-a-second ) of a nuclear explosion can travel hundreds
of kilometers before colliding with electrons in atmospheric molecules.
 That kind of collision may take place in a region 2,000 miles in diameter and
6-miles thick.  Electrons are accelerated by those collisions, a phen-
omenon referred to as the Compton effect; and upon reaching the earth's
magnetic field, they set up electromagnetic pulses that radiate downward
toward earth (Fig.1).  Due to the extremely large area of collision, vast
amounts of ground area are exposed to electromagnetic fields with strengths
up to 50,000-volts per meter.  The ground area exposed to electromagnetic
pulses could cover the entire continental United States and most of
Canada by one nuclear blast; if not, certainly large regions such as New
England would be electrically and electronically devastated.
FIG. 1 -- Electrons set into motion by gamma rays from a nuclear explosion in
space will produce enormous electromotive pulses (EMP's) when the negative
charges enter the Earth's magnetic-field. It is estimated that the ideal
height for such an explosion should be 250 miles above the Earth's surface.
::::::::::::::::::::::::::::::::::::::::                                     :
:               O - Nuclear Explosion ::                                     :
:             /  /                    ::            /  /   - Gamma Rays      :
:   ---------------------------       ::  <  Earth's Magnetic Field   >      :
:   ---------------------------       ::   *******   *******   *******       :
:    *****     *****     *****        ::     ***  EMP  ***  EMP  ***         :
:    *****     *****     *****        ::   *******   *******   *******       :
: ===============================     ::            EARTH                    :
:                                     ::::::::::::::::::::::::::::::::::::::::
  Vulnerability  -------------
THE effects that electromagnetic pulses would have on a mass of circuitry are
difficult to predict because the interactions are complex.  But, the more
complex the components, the easier they are to damage.  Power lines are one
avenue for EMP damage, and a company making a shielded tubing to go over
power and signal carrying conductors obviously had EMP in mind when they
invented their "Zippertubing". That covering acts as a partial shieldto EMP's.
FOR each component, damage would come from the internal pickup of the circuit
itself, as well as surges fed to it by all other attached conductors (power
lines, other circuits,and metal parts). ANOTHER concern is that generators and
motors with their numerous internal windings of copper wire could be
rendered useless in an EMP attack; and with subsequent inoperative water
pumping stations, desert population-centers could persih.  In the dead of
winter, motors in heating units would be destroyed and the chilling freeze in
the northern portions of the North American continent would bring those
areas to a standstill.  Food and fuel shipments would halt because fusible
links and electronic ignitions would be destroyed in cars and trucks.  It's
difficult to conceive a family anywhere on the continent not suffering extreme
hardships.THE more complex the electronics components, the more vulnerable they
are to electromagnetic pulses. Hardness describes the vulnerability of an
electrical device and it is best for old-style vacuum tubes, less for semi-
conductors, and even less for microcircuitry.  It would take 100 times
more EMP energy to damage the tubes than integrated circuits.  Computers
may be upset through memory erasure with 100 times less energy than
required to damage integrated circuits; refer to Fig. 3.  Aircraft in the air
and parked on open surfaces would be disabled, because electronics controls
the crafts' flight instruments and control surfaces.
::::::::::::::::::::::::::::::::::::::::(-8)(-6)(-4)(-2) (1) (2) (4) (6) (8) :
:::!:::!:::!:::!:::!:::!:::!:::!:::!::::                          ######     :
:                                     ::         $$$$$$$$                    :
:                                     ::      %%%%%%%                        :
:                                     ::    &&&&&&&                          :
:                                     ::::!:::!:::!:::!:::!:::!:::!:::!:::!:::
:(-8)(-6)(-4)(-2) (1) (2) (4) (6) (8) ::( Powers of TEN)             :
::::::::::::::::::::::::::::::::::::::::  RANGE OF THRESHOLD ENERGY, JOULES  :
:::::::::::::::::::::::::::::::::::::::: # = Motors and Transformers         :
: $ = Vacuum Tubes                    :: % = Low-Power Transistors           :
: & = Integrated Circuits             ::::::::::::::::::::::::::::::::::::::::
  Hardening Communications Equipment  --------- -------------- ---------
HARDENING of electronics communications equipment is vital to the military,
and, to a lesser extent, the civilian populace.  The Department of Defense
has established an Electromagnetic Compatibility Program (EMCP) to ensure
that all military Communication-Electronic (CE) equipment subsystems, and
systems are protected from electromagnetic interference of all kinds.
That program was implemented to ensure that electromagnetic compatibility is
maintained through design, acquistion, and operational phases. Numerous semi-
conductor manufacturers now produce what are called "radiation-hardened"
integrated circuits, just for that reason.
THERE are three major design criteria which must be considered when hardening
against EMP's.  They are cost, the equipment's ability to survive EMP, and
failure rates of the shielding components.
COST includes both installation and maintenance.  Some protection practices,
such as shielding the entire communication site, may be attractive from a
technical point of view, but are impractically expensive.
THE electronic equipment's ability to survive an EMP attack must be measured
in order to determine how much EMP protection is needed.  A testing device
for measuring the radiated electromagnetic susceptibility of an elect-
ronic device is a Transverse Electromagnetic Mode (TEM) cell.  A TEM cell
consists of a group of electronic instruments and a special specimen holder
that simulates an environment of free space.  The TEM cell is used for per-
forming electromagnetic interference/electromagnetic compatibility (EMI/EMC)
measurements and evaluating protection devices.  Shielding Methods
  --------- -------
IN order to predict the effect of an electromagnetic pulse on electronic
equipment, it is necessary to assess the enviroment.  The structures housing
the electronic equipment are made in various shapes and sizes, and are con-
nected to the outside world by conductors such as utility lines and pipes,
communication lines, and access and ventilation structures.(Refer to fig.5)
That combination of criteria makes the exact determination of the interaction
of an EMP with such a variety of structures extremely difficult.  However,
for complex systems, it is convenient to have several layers of shielding.
(Refer to Fig. 6).:::::::::::::::::::::::::::::::::::::::
:   EMP                  Lightning    ::  ////                   V V V       :
:   ------------------------------    ::   !*            Building       !    :
:P--+**                          !    ::   !*                           !    :
:   !   EMP Penetration          !    ::   !                            !    :
:   !                            !    :: +-+    *                       !    :
: ! !   ***                      !    :: ! -----!------------------------    :
: !      !                            ::=!======!==========================  :
:Gnd     ! - Buried Cable             ::--------+                            :
::::::::::::::::::::::::::::::::::::::::  P = Power Lines        Fig. 5. --  :
: -- A sealed metal box is an ideal   :: structure for eliminating EMP pen-  :
: etration. However, power lines and  :: signal cables require entry ports   :
: thus compromising the integrity of  :: a shielded building. Obviously, it  :
: is apparent that doors and windows  :: would have a greater leakage effect.:
::::::::::::::::::::::::::::::::::::::::               Shield 1              :
:         ********************        ::        *  Zone 1 (internal) *       :
:       *    ==============    *      ::      *    =    Zone 2    =----*     :
:      * g =   ##########   = g *     ::      * r =  ############  = r *     :
:      * o =--###ZONE 3###  = o *     ::      * u =  ############--= u *     :
:      * n =   ##########   = n *     ::      * d =   (cabinet-    = d *     :
:       *---= environment) =   *      ::        *   ==============   *       :
:         *   Shield 2       *        ::          ******************         :
:    !------!                         ::    !                                :
:    !        Zone 0 (External-       ::    !                Environment)    :
:----!--------------------------------::    =     EARTH                      :
:                                     ::::::::::::::::::::::::::::::::::::::::
: Fig. 6 -- More than one shield can  :: be used to secure the environment of:
: the machinery and electronic mat-   :: erial contained within a building.  :
: The building can provide the initial:: shield. Shielded rooms or metal cab-:
: inets may provide a second shield.  :: A third shield (not diagrammed)     :
: would protect entry cables from     :: violating the shielded area of      :
: zone 3.                             ::::::::::::::::::::::::::::::::::::::::
  Shield 1  ------ -
A structure composed of a great deal of metal is well shielded against electro-
magnetic pulses, while a building made primarily of wood is virtually un-
shielded against EMP's.  Continuous, closed sheet-metal shields are, by far,
the most effective electromagnetic shields.  It is imperative that the in-
ternal environment of zone 1 be connected to the outside world.  That fact
makes a closed sheet-metal shield impossible.  Aperatures in shield 1
create a special problem in protecting communication sites from EMP penetra-
tion.THE electromagnetic field penetration depends on the aperature size.  If a
given area of wall opening is subdivided into ten small openings having
the same total area, the penetrating EMP fields at an interior point will be
1/SQR(10) as large as for a single large opening of the same total area.
(Refer to Fig. 7).
Therefore, it is better for a structure to have more small openings than
just a few larger openings.
A common treatment for such openings is to cover them with a conducting
screen or mesh so that the large opening is converted to a multitude of
small openings, or use a glass impregnated with metal.  That glass, despite
having metal in it, offers approximately the same degree of visual att-
enuation or lack of clarity as looking through a screen door from within the
:        !!           !!              :: ###### !!  ######## !!              :
:      # !!         # !!              :: EMP *==!!         # !!              :
:      # !!         # !!              ::      # !!    E   *==!!              :
: EMP *==!!    M  **==!!              ::      # !!    P  **==!!              :
:      # !!        *==!!              :: EMP *==!!         # !!              :
:      # !!         # !!              ::      # !!         # !!              :
: EMP *==!!         # !!              ::      # !!         # !!              :
:      #            #                 :: ######     ########                 :
:    Shield       Shield              ::::::::::::::::::::::::::::::::::::::::
: Fig. 7 -- The electromagnetic field :: penetration into a ported shield is :
: minimized by reducing the size of   :: the openings. In the diagram the    :
: open area of the port of the example:: on the right is equal to the sum of :
: the areas in the example at left.   :: The diagram clearly shows that the  :
: penetration of an EMP is less when  :: equal areas are summed from several :
: small ports.                        ::::::::::::::::::::::::::::::::::::::::
  Shields 2 and 3  ------- - --- -
THE second-level shield seperates the internal environment from the sensitive
small-signal circuits within the electronic equipment found within Zone 2.
Shielding here may be accomplished by electrically grounding the metal cabin-
ets and equipment.
SHIELD 3 involves the shielding of the interconnection of the equipment.  That
could involve elaborate design of interconnecting signal transmission lines.
 Fiberoptic signal transmission shows great promise here because it is
not effected by any type of electromagnetic interference.
  Hardening Aircraft and Missles  --------- -------- --- -------
GENERALLY, the EMP interaction with electrical systems inside structures such
as aircraft and missles depends upon a multitude of factors.  Aircraft and
missles usually have a nearly complete metallic exterior covering that serves
as a shield from electromagnetic fields.  However, that shield alone is
not enough protection against electromagnetic pulses.
Missles and Aircraft are equipped with computers that cannot be upset even for
an instant.  They must be partically well hardened.
AT the present time, there is no agreement on the most effective ways to
harden aircraft and missles.  Heavy shielding, like the type used at com-
munication sites, is obviously impractical because of the added weight that
the aircraft has to carry.  Instead, EMP resistance is designed into the
aircraft's equipment.  One example of that would be in the area of circuit
design.  Small loops make better antennas for EMP's than short straight
lines; therefore, circuits are designed in tree or branching layouts rather
than in more conventional circuit loops.  Is Shielding Help on the Way?
  -- --------- ---- -- --- ----
IN the last decade, electronic devices have proliferated in all areas of our
lives.  That influx of products has caused a problem: Noise Pollution, or
EMI/RFI ( electromagnetic/radio frequency interference).  Over 80,000 cases
of noise pollution were reported to the FCC (Federal Communications Commission)
in 1982.
STRANGE as it may sound, the plastics industry is coming to the rescue with
plastic electronic-equipment enclosures specifically designed for both EMI con-
tainment and shielding.  Obviously, with EMP's as an external disturbance, the
containment of a field is academic, but the shielding from an outside field is
crucial.  The parameter describing that is Shielding Effectiveness (SE) and the
equation for shielding effectiveness is          SE = A + R,
or shielding effectiveness equals Absorbed plus Reflected energy.
HIGHLY conductive materials such as pure metal shields reflect approximately 99
percent of the energy and adsorb 1 percent.  But plastics with metallic comp-
osite fillers, metallic paints and sprays, or even impregnated wire meshes
still reflect 80 percent of the energy and absorb 20 percent.  If EMP's and the
disturbing effects of electromagnetic fields still seem like an abstraction or
a physicist's dream, consider that event.
A manufacturer of buses designed for city use had just delivered a fleet when,
during a test drive, a problem was discovered.  After going over the top of a
hill, the driver tried to brake, only to discover he had no brakes until he got
to the bottom of the hill.  Upon logical investigation of that problem, field-
strength meters demonstrated that a local television station had a lobe-shaped
radiation pattern that intersected the hill's apex.  The microprocessor-
controlled anti-skid braking system on the bus had sensitive circuitry that
became inoperative because of the TV signal.  The bus, though, was made safe
by properly shielding the enclosure housing the electronics.  Graphite,
a moderately good conductor, is fabricated within large plastic sheets
for applications such as that.
IF a signal as small as that can effect circuitry that drastically, you can
imagine what an EMP could do and likewise you can see how crucial EMI
shielding is.  But will EMI shielding be universally implemented into new
equipment?  The Military's Involvement  --- ---------- -----------
THE military is very concerned with EMP's. The Army has established its
Aurora Tree test facility in Aldelphi, Maryland.  The Navy has the Casino and
Gamble-2 x-ray emitting facilities, but the Air Force probably has the most
interesting project of all.  It is the Trestle, after the railroad structure
it resembles.
THAT 12-story (118 feet) high, 58-meter (200-foot) square deck is flanked by a
50-foot wide adjoining ramp upon which aircraft to be tested are rolled up.
 The Trestle can support aircraft weighing 550,000 pounds and is built
with one-foot by one-foot wooden columns using no nails or metal of any
kind.  That largest glue-laminated structure in the world uses 250,000
wooden bolts to hold its six-million board feet of lumber together ---
enough for 4,000 frame houses.  The structure at Kirtland Air Force Base,
New Mexico cost approximately 58-million dollars.
THE Trestle has two 5-million volt pulsers that discharge energy into
wire transmission lines surrounding the aircraft under test.  Sensors
capture aircraft response signals and fiber-optic channels transmit
that sensor data to computers for processing.  The processing equip-
ment, though, naturally resides inside a very well shielded structure.
The B-52G's OAS (Offensive Avionics System) is one of numerous studies
directed primarily at testing the electronic hardening of militarysystems.
  The Future  --- ------
THE effects of EMP on our lives is becoming known to many on the North
American continent as it is being discovered by all the citizens of
the free world.  Its political implications are not the topic here,
but rather the facts in this article reveal to what EMP is and what it
can do to the technological devices we rely on every minute of the day.
The next time a solar flare disrupts radio communications around the world
for a few hours, or maybe a few days, recall that man with one nuclear
device can outshine the damage old Sol creates by many fold.  GLOSSARY OF TERMS
ElectroMagnetic Pulse (EMP):  An electromagnetic field of high
intensity and short duration that may be caused by a nuclearexplosion.
Electromagnetic Field:   A magnetic field produced by elect-
ricity (the flow of current in a wire or electrons through a medium
such as a vacuum). It is usually expressed in volts per meter.
ElectroMagnetic Compatibility (EMC): The ability of an electronic device
to deal with electromagnetic interference and function properly.
ElectroMagnetic Interference (EMI): Any adverse effect on electronic
equipment due to an electromagnetic field.
Shielding or Hardening:  A method used to protect electronic devices
from EMP interruption or damage.          -----------------------------------
 Written: Art Reichert / March 21, 1988
                  Understanding Electromagnetic Pulse
         How to Prevent Resulting Damage to Electrical Equipment
______________________________by Joe Bobier____________________________
One  of  the  many  fables of nuclear war that has been worn out in an
effort to convince us all of the futility  of  it  all  is  EMP.  When
understood, the problem can take on realistic proportions.
When  a  nuclear  explosion occurs, a very broad spectrum of energy is
released. It ranges from nearly  DC  (o  KHZ)  to  beyond  1021  hertz
(gamma  rays).  The  portion  concerned with here ranges from 0 KHZ to
1000 GHZ (beyond radar uses).
Two  basic  sorts  of  damage can occur as a result of EMP. The first being
what we will call " power line " type of damage, and the other  being  what
I'll  call  "  radio  "  damage.  Power  line  damage is resultant from the
induction of high levels of current into relatively long wires such as home
or shelter wiring, electrical generating system wiring such as  the  cables
running  to and from PV ( photovoltaic ) panels, generators, windmills, and
of course in the already famous auto electronic ignition system. This  type
of  damage  can  be  virtually  eliminated  by a multi-level approach, that
provides front line defenses, and various levels of backup systems  in  the
event  that  EMP  should  overcome the first level of defense. This layered
defense method has proven  highly  reliable  in  commercial  communications
systems  where radio towers are subject to severe direct lightning strikes.
Even with such severe EMP and direct surge  conditions  which  excede  most
predicted  EMP  conditions,  the  communications  systems survive often for
years of storm seasons.
The first layer of EMP defense is the THYZORB. This is a solid state single
junction device similar  to  an  avalanch  diode.  Its  maker  is  National
Semiconductor, and it is distributed by Square D. You should purchase these
devices  specifically  matched  to  the  type of system voltage you wish to
protect. For instance, if you wish to protect  a  12  VDC  PV  system,  you
should  consider  that the open circuit voltage of most PV panels is around
19 VDC so a 25 VD  C  THYZORB  would  provide  excellent  protection.  Also
remember  that  as  the  amount of current through the device increases, so
does the voltage drop across the device. Generally about 10 VDC  is  to  be
expected  at  maximum  rating,  thus we can expect that no more than 35 VDC
will develop at the protected area.
I would place a Thyzorb on each panel at the output terminals and then  one
more  at the junction of the panels where your main feed line is connected.
The THYZORB is available in many power  ratings  from  1.5  KW  to  15  KW.
Generally  you should be safe with the small ones on the panels, and the 15
KW unit at the junction point. At the other end of the feedline add another
THYZORB just as the first one at the junction point was.  The  device  only
has  two connections on it which are placed directly across the lines to be
protected.  Under  normal  conditions,  the  unit  has  no  effect  on  the
circuitry.  The  unit  is  reliable  and  re-useable.  After  thousands  of
operations, it will still be as good as new. The reaction  time  for  those
who  wonder  about  such things is about 10 nano seconds. In the event your
cables are longer than ten feet or so, it wouldn't hurt to  add  a  THYZORB
every  ten  feet.  THYZORBS are available in many voltages and in AC or DC.
This means you should be installing them in any AC lines such  as  inverter
outputs  or  generator  outputs.  I  would put one in every wall outlet and
light fixture also. Now for the layered effect I mentioned earlier.
In the event the THYZORB fails you need to have another device in place  to
soak  up  the  balance of the surge. In low voltage DC systems your choices
are somewhat limited. You could use an MOV ( metal oxide varistor ).  These
are  devices  made by General Electric. They are widely available at stores
like Radio Shack. The only problem with MOV's is that every time they  fire
(see  a surge) they drift in value a little. Pretty soon your surge stopper
isn't turning on at the right time or worse yet fails  altogether.  In  low
voltage systems, you can't really use a gas discharge tube, since they only
work  at  150  volts  or higher. By then your low voltage equipment will be
fried. Instead, at the risk  of  sounding  redundant,  I  recomend  another
THYZORB  but selected at a slightly higher voltage. Five volts higher would
be a good choice since the second one would only fire if the first one were
working at 1/2 of its full capacity. This would  cause  a  current  sharing
condition  and  increase overall device reliability. You could in theory go
several layers in this manner until you felt completely safe,  or  you  ran
out  of  EMP  money.  The  actual  connections would be to earth ground the
negative (-) side of your DC power system in several  locations.  Use  long
bronze, brass, or copper rods with heavy, short cables to the power system.
Next  attach  the  negative (-) side of the protection device, ( THYZORB or
other ), to the ground system. Finally, attach the  positive  side  of  the
protection  device  to  the  positive  side  of  the power system. In an AC
system, you can do exactly the same as above with proper device  selection.
You may also use a gas discharge tube here since we are dealing with a high
voltage to start with. In this case you will have three wires to deal with;
one  for  each  side  of  the  AC,  and  one  for  earth ground. Additional
preventive measures include  grounding  the  frame  of  the  PV  panel  and
grounding  generator  frames.  A good earth ground is very important if you
use gas discharge tubes. If scenes from the " DAY AFTER " have you paranoid
about being trapped in an immobile car, then take heart. You can EMP  proof
your  auto  electrical  system  the same way as your low voltage DC system.
Just put a couple layers of THYZORBS or MOV's across the DC  input  to  the
ignition  system.  A few more sprinkled here and there like the power wires
of your CB radio, or your AM/FM receiver will work wonders. An easy way  to
reduce the risk of appliance damage in your home or shelter, if it is an AC
device  is to use a personal computer style surge protector. They are cheap
and very easy to install. Most of these devices use  MOV's  or  better  yet
THYZORBS or avalanch diodes.
The National Communications System (NCS), a governmental entity
made up from 22 different Federal agencies, wants ham radio
operators and their gear to survive an EMP (Electro-Magnetic
Pulse) generated "nuclear event."
NCS engineers have simulated the EMP phenomenon in the laboratory
and have subjected various pieces of current amateur radio gearto its effect.
The people at NCS came to some rather surprising conclusions.
In their report they say, "It was concluded that modern
solid-state amateur radio equipment was more survivable in an EMP
transient environment than had been previously anticipated."
What makes those sophisticated and delicate transistors and ICsso survivable?
The secret is in having two EMP surge protection devices.  One is
needed on the end where the power comes into the radio and the
other on the antenna end where the RF signal goes out.
The NCS tested various commercially available suppression devices
designed for both lightning and EMP and, in a move surprising for
any governmental agency, issued a report telling which ones
worked and which ones didn't.
Their findings and recommendations are outline in a 105-page
publication entitled "Electromagnetic Pulse/Transient Threat
Testing of Protection Devices for Amateur/Military Affiliate
Radio System Equipment"--otherwise known as NCS Technical
Information Bulletin 85-10.
When considering EMP protection for transient voltage spikes
coming in through commercial power lines, the folks at NCS
recommend the TII model 428 plug-in power line protector, an item
which costs only $45.  But for those a little strapped for cash
(and what survivalist isn't), the report shows how you can make
one yourself for an estimated cost of only $11.
For EMP protection on the antenna side of a rig, NCS recommends
the Fisher series of spikeguard suppressors.  They come in a
variety of different clamping voltages, depending on the
characteristics of a specific station.
The bulletin provides a mathematical formula to determine which
fisher model is correct for your radio.
The Fisher devices cost $55, thus giving hams total effective EMP
protection for their radios with off-the-shelf items for only$100.
If your radio has a power output of 100 watts or less, a second
coax protector was recommended, the PolyPhaser products.  They
proved to be just as effective as the fisher products but cost
somewhat more--$82.95 each.  Because of their lower clamping
voltages, they are recommended only for lower wattagetransmitters.
But again, for those handy with electronics, NCS shows you how to
make a simple home-made protection device for your antenna systemfor only $9.
It was interesting to note that two relatively inexpensive
devices simply did not work.  The Archer (Radio Shack brand) AC
line protector was NOT recommended.  Nor was the Alpha Delta
brand "Transi Trap" coax protector, commonly advertised in hamradio magazines.
Other interesting findings made by NCS engineers were that
portable generators, such as Honda types, were not likely to be
adversely effected by EMP at all.  Neither were hand-held walkie-
talkie type portable radios, particularly those with short stubby
"rubber duck" antennas.
The importance of a proper grounding system for amateur radio
stations was discussed in the report with specific recommen-
dations for maximum effectiveness.

-- Anonymous99 (Anonymous99@Anonymous99.xxx), March 30, 1999


Well that worked "well". If the post is too messy to keep, old- timers please feel free to put in a delete-request.

Hopefully, though, the post presents a few buzzwords for folks to seach on using their favorite web search-engine for more readable text.

-- Anonymous99 (Anonymous99@Anonymous99.xxx), March 30, 1999.

I use to car pool with a gent who was at several of the tests out in the pacific. He relayed to me that one of the ways that the EMP effect of Thermonuclear Weapons was after the Upper atmospheric test they would come back to Hawaii and Lots and Lots of the street lights were all burned out... Evidently it took several times before the cause and effect were put togeather... Hawaii is a long way from the test sites.....

EMP can be a very effective WMD........

There is talk that the Soviet Anti Missle system is based on Upper atmospheric Blasts that stop the missle but make a big EMP blast below... Thus you are damned if you do and damned if you don't......

TEOTWAWKI comes in many forms and flavors...

-- helium (heliumavid@yahoo.com), March 30, 1999.

Thank you very much for posting this, Anonymous99! For us clueless war+weapons newbies, explanations are much appreciated.

Yet another way to become toast! Yourdynamites 101 toast recipes -- some not requiring the 5-mile circumference of a 7-11.

xxxxxxxx xxxxxxxx xxxxxxx

-- Leska (allaha@earthlink.net), March 30, 1999.

Yep, the U.S. has kept obsolete vacuum tube air traffic control systems in place all these years just because of lack of funding. Or maybe the powers that be were just stupid not to have gotten around to updating those systems? Of course it couldn't possibly have anything to do with the fact that vacuum tubes are not affected by electromagnetic impulses.

-- Bonnie Camp (bonniec@mail.odyssey.net), March 30, 1999.

Nice three-part message - the first part was wild-eyed and repeated most cliches I've heard on the subject, the second was pretty good, and the third mentioned a pamphlet I have in my possession, namely bulletin 85-10. Interesting thing about that last - in that bulletin they describe subjectiong ham gear to EMP without ANY protection, and guess what? It survived, all of it except a transceiver that had minor power output problems (too much, not too little). They found that that the EMP surge will arc through the coax dielectric, which acts as a surge suppressor. NONE of the equipment was "knocked out" by the EMP... neither will your car, or your transistor radio, or your generator, or almost anything else electronic you have, unless it's hooked up to the power grid and gets a surge via that route. EMP isn't the bogey-man it's cracked up to be.

-- sparks (wireless@home.here), March 30, 1999.

I remember of a story of a russian pilot who escaped from USSR with it's MIG (MIG23 I think) US army dismantled the MIG and nearly died of laughing when they see it was working with vacuum tubes...

until EMI specialists tol then that this plain was the only on to really resist to an EMP.

as far as I know USSR was using very rough machines, like a transport van that was tested to support a nuclear blast (supersonic shock wave),. the only thig you have to do was to put this vehicle on it's wheel (the shock wave make it roll like a bush ball) and turn the key.

in any case if you feel someone is really stupid, be carefull ... the most stupid might not be the one you think...

-- Alain Coetmeur (alain.coetmeur@wanadoo.fr), December 20, 2002.

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