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Author Topic: Protecting equipment from EMP  (Read 361 times)
KC2ELS
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« on: February 19, 2004, 06:48:23 PM »

My wife has apparently decided to humor me in that she has agreed to permit me to construct a backyard shelter whenever we get around to buying a house -- providing that it also becomes my radio and server room.  This isn't really a problem for me since I had planned on doing this anyway, but it got me thinking: what's the best way to protect my equipment from damage caused by EMP?

I spent some time this afternoon researching this on the Internet, and there really isn't much out there:

 * use equipment as little as necessary,
 * store equipment in a Faraday cage when not in use, and
 * maintain a stock of spare parts

Given the history of amateur radio and emergency communications, one would figure this kind of preparation and information would be a little more complete and easier to find.  Does anyone have any suggestions as to where I can find more information on this topic that is complete, accurate, and useful?
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AA4PB
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« Reply #1 on: February 19, 2004, 07:15:41 PM »

Keep an older, all-tube type of radio. Pick up a good used Collins KWM-2.
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W5HTW
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« Reply #2 on: February 19, 2004, 07:30:56 PM »

Most of that disappeared with the "alleged" end of the Cold War.  No one is selling "Atomic Bomb Shelters" anymore, though I'm sure Home Depot wouldn't mind if there was a market for them.  

I suspect most hams are more interested in protecting themselves from nuclear weapons than their radio gear. Certainly I would be.  And besides, after a nuclear attack, who ya gonna talk to?  I admit I'm being a bit facetious here, and it is not good to be complacent.  But the nuclear attack paranoia seems to be sort of passe.  In fact, even the militia types appear to have crawled into their holes (with EMP-protected radios) and disappeared from the scene.  

As the other respondent says, though, get tube type gear and be sure it is working.  Build your shelter very deep and with very thick walls, lined with lead.  Stock it for three months minimum with food and water, disposable camper toilet facilities, batteries, extensive first aid, water collection and treatment, and ham radio.  Then, a few weeks after the attack and you are tuning about the bands, if you hear anything but static, try and contact it/them/those/whatevers/whomevers!  

Oh, by the way, get a KMW2-A, so you are not limited to ham bands, and totally stock it with crystals.  Get the DC power supply, several sealed lead-acid batteries, a hand-cranked generator you can use to charge the batteries, (you will have plenty of time to crank it, and it will give you exercise - crank it one hour with your hands, the next with your feet - and it can supply your lights as well!) a retractable whip antenna you can pull down through the roof of your shelter, a Collins military antenna tuner that will tune the whip on any frequency above say 3 mhz, (aviation type tuner)

Or, just hope the Cold War is really over.  It isn't, but you can hope!

73
Ed
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W8JI
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« Reply #3 on: February 19, 2004, 09:54:20 PM »

By the time equipment not connected to antenna is damaged by EMP, you're dead anyway.  
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N6AJR
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« Reply #4 on: February 19, 2004, 10:51:49 PM »

in the service we used a "screen room" for different reasons but none the less, it was a room completely shielded by brass screen ( like window screen) and it was bonded together on the joints and the door had fingerstocl to make contact.. no rf in or out.. If I told you any more I'd have to kill you  Smiley
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KC2ELS
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« Reply #5 on: February 20, 2004, 04:38:42 AM »

Actually, shelters are for sale these days, if you look in the right places.  <a href="http://www.radshelters4u.com/mini-blast-shelter.htm">Here</a> is a simple shelter that's already built and is waiting to be buried in a backyard near you.

This wouldn't really be suitable for my needs, though.  I'd be more interested in something like that described <a href="http://oism.org/nwss/s73p928.htm">here</a>.

While I don't think the former pinkos are going to lob little gifts of plutonium over the Arctic Ocean any time soon, I do live in six-land and I wouldn't be surprised if the North Koreans decide to deliver something precious and wonderful across the Pacific should push come to shove over there.

As for screen rooms, I've wanted one of those for my computer equipment ever since I saw one for the first time.  I've built a small Faraday cage out of window screen roughly three feet on a side, and an experiment showed that it attenuated signal on 2m by roughly 19db.  The only thing keeping me from building one for my rack of computers is the lack of knowledge on exactly how to pass power and data through something like that.

Pointers to useful documentation on either topic (they're pretty much the same topic when I think about it) would be dearly appreciated.  The best docs I can find on TEMPEST shielding are on Cryptome, and they're helpful in general, but not in specific.
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KA2UUP
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« Reply #6 on: February 20, 2004, 10:00:23 AM »

Take it from somebody that was familiar with this type of work.  As somebody said above, save yourself first and forget the equipment.  The joke in the USAF in the 70s 80s was that the equipment would survive but nobody would be around to operate it.  In addition to that, you will be spending a lot of money on specialized conduit, gounding systems, filters and arrestors and hardened shelters with fingerstock sealed doors.  You are not talking money in the kilo range, but mega-money.

But, seriously, based on the analysis of the threat, the probability of a nuclear attack is low to nil.  I would suggest protecting the equipment against natural catastrophes and conventional explosives.  A dirty bomb, if one is ever exploded in the states (God help us!), will only contaminate the area with radiation but not generate any EMP.

73 DE Bert @ KA2UUP
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KA2UUP
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« Reply #7 on: February 20, 2004, 10:07:38 AM »

BTW, I forgot to mention that the only frequencies that are effective in an EMP environment are in the LF to ELF range.  Forget everything above 1 MHz.

Bert @ KA2UUP
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N6AJR
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« Reply #8 on: February 21, 2004, 01:49:59 AM »

smoke signals...
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KA5S
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« Reply #9 on: February 21, 2004, 04:50:17 PM »

Some years ago, maybe 20, a study was done that included the vulnerability of Amateur equipment of the time to high altitude EMP. This was, as others have suggested, the only kind of nuclear EMP against which one would reasonably need to protect, since the other kind would require affected equipment to be in the near effects zone of the nuclear device causing it. Poof!

The upshot was that protecting equipment from electrical overstress due to HEMP-induced potentials **on attached wiring** was the key to making a station survivable. Since the most advanced radio tested was I believe a Drake TR7, the study is probably not adequate now, but it was pretty interesting.  I have not been able to find it on the ARRL site or the Web.

In a different category are radio frequency weapons. These have spectra which may extend well up into the microwave range, and can put enough energy on boards and parts directly to blow junctions and play hob even with traces and wires.  Rumor has it some were tried at the beginning of the invasion of Iraq.

Against these it appears the only reliable protections are distance and shielding -- and plenty of both.

Cortland
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