[RFI] Meter Sensitivity to Surges

[Tom Rauch]

> The portion of your comment that I left in below needs 
> some additional
> remarks.  There was some particle of fact in what the 
> person talked about
> at the session you attended.

No, there wasn't. I was there and it was nonsense.

> First, EMP remains an active concern in the design of 
> military and
> emergency communication systems, especially those 
> operating in the HF
> spectrum.  Thus, there are test facilities that specialize 
> in EMP testing
> of such systems.  The test consists of discharging large 
> capacitor banks
> into a tank circuit that is connected to large arrays of 
> wires, under
> which the system to be tested is located.  However, no 
> explosive charges
> are used to generate the energy for the pulse.

This fellow was paid to talk about buying a big capacitor 
from Newark, not something room size, and sending a 
destructive pulse for 25 miles.
The system you are describing tests things at a very smal 
distance by placing things in the nearfield of a localized 
source.

One is reality and good engineering but still very difficult 
to create and not portable, the other is total  rubbish.


> Finally, the mechanism described by the speaker Tom heard 
> is not
> far-fetched;

It was rubbish. I was there, you were not.

  in fact, that is EXACTLY the approach used by the Russians
> in some of their non-contact electromagnetic missiles.  (I 
> was in
> attendance at a high energy weapons conference several 
> years ago in
> Albuquerque, NM.  Attendees included several US and 
> Russian experts in the
> field.  During the conference, the Russian delegation 
> astounded everyone
> by making a presentation of just how they were able to 
> generate several
> GIGAWATTS of 94 GHz RF on a missile.  In short:  a battery 
> supplies a
> small DC current through an inductor [which is physically 
> long] that has a
> capacitor at the far end.  Also attached to that far end 
> is a gyrotron,
> mounted in the missile nosecone, at the focal point of a 
> dish antenna.
> When the missile is at some predetermined range from the 
> target, a
> chemical charge is ignited, the resulting pressure wave 
> pushes a piston
> that collapses the long inductor very quickly, and the 
> resulting dV/dT
> [big step function] charges the cap with a LOT of energy, 
> allowing the
> gyrotron to deliver gigawatts of power before the whole 
> thing flies apart
> from the blast.)

Which is NOTHING like someone carrying  a capacitor, 
battery, and an airwound coil to an area and releasing 
broadband energy that destroys vehicle wiring and all 
communications for miles.

In your description the energy is focused by a high gain 
antenna, with very narrow beamwidth and narrow bandwidth. In 
the Quack case Joe the Terrorist runs off to Newark and 
buys some electrolytics, and builds a big coil that is 
connected across the capacitor. At the moment his big 
electrolytic is attached an explosive collapes the coil, and 
everything for many miles stops. This is sheer nonsense. The 
energy in the explosion would have more range than any 
pulse.

> So, as is often the case, there was some truth to what was 
> said.  I
> suppose that if this person were to connect a "fast 
> collapsing" coil to a
> cap and some sort of antenna, there would be a pulse 
> radiated.  The range
> of interference would certainly be a function of the power 
> created and the
> antenna system, among others.  I think that "wiping out 
> all communications
> for miles"    is probably stretching the point a bit, but 
> real nuke blasts
> will cover a lot more than "miles".

If a real nuke blast generated that type of pulse, we would 
not be around to worry about the radios or cars.

> Doc asked a good question.  In general, if you are 
> protected for
> lightning, you will be OK for EMP, but be advised that EMP 
> has a faster
> rise time than lightning.

Faster rise time means higher frequency.

>  Modern solid state equipment is typically
> small, so as long as there are no unprotected long leads 
> connected to a
> given device, it will not be affected by the EMP field.

Longer leads mean lower frequency.

One expert on EMP
> and related issues is ARRL Roanoak Division Director, 
> Dennis Bodson,
> W4PWF.  Way back in the 80's, Dennis was employed in one 
> of the Government
> agencies, where he wrote a multi-volume reference on EMP 
> and system
> deisgns for protection.  My employer at that time had an 
> interest in those
> issues from a marketing viewpoint, so I obtained the full 
> set of manuals
> written by Dennis and his staff.  Those books served as my 
> introduction to
> EMP.

I'm not going to get into long political arguments about 
implanting paranoia, but if we look at the decrease in 
energy level with distance of a non-focused source and the 
slope of attenuation of higher frequencies with distance one 
of the last things we need to worry about in todays 
political climate is EMP. It was already overrated, but 
needless fear keeps us distracted and money flowing.

People can do what they like, but I'll protect my station 
with a rifle and shotgun. When the big "attack" comes we 
will find our food supply tainted, our children posioned, 
the country full of illegal undocumented people, and our 
military resources squandered and wasted to the point where 
we can't defend ourselves against any real threats like 
people just walking in or even bad storms.

73 Tom