EMP immunity

[AK9R]

I get asked frequently what I think the risks of EMP events are.

I wish you were sitting at my table at the hamfest I was at this past Saturday. A guy stopped to chat. Seems he was in the market for tube-based amateur radio gear because it wouldn't be susceptible to EMPs. I couldn't explain it to him, but I suspect you could have.

 

[trentbob]

I would be very interested in hearing about a faraday bag or cage for electronics. Can a homemade one actually be a possibility?

 

[AB4BF]

I would be very interested in hearing about a faraday bag or cage for electronics. Can a homemade one actually be a possibility?

US military metal ammo boxes make very good EMP shields. Finding one big enough for a larger size radio may be a challenge. Know this: Just like lightning, EMP pulses in some cases aren't stopped too well either. If a nuclear detonation happens over your home or work, you most probably won't have to worry about communicating with anyone any more anyway...

Think Starfish Prime... https://www.thoughtco.com/starfish-prime-nuclear-test-4151202

 

[trentbob]

US military metal ammo boxes make very good EMP shields. Finding one big enough for a larger size radio may be a challenge. Know this: Just like lightning, EMP pulses in some cases aren't stopped too well either. If a nuclear detonation happens over your home or work, you most probably won't have to worry about communicating with anyone any more anyway...

Think Starfish Prime... https://www.thoughtco.com/starfish-prime-nuclear-test-4151202

It's just amazing that we used to light those puppies off in the sky like that, I'm in my late sixties and was part of that generation that would get under the desk at school and even in those days as little kids we would follow our instructions to bend over and kiss our... well you know the rest.

I agree that if we actually have a nuke go off nearby it really doesn't matter LOL. I guess there's always the threat of a solar flare and now we have all the talk of the new solar cycle, I remember the 70s and the 90s.

I have several of those standard size ammo boxes. Good tip.

I'm also curious if tube radios are immune to EMP. I can remember the debate about Russian aircraft using tubes in their electronics when the nuclear age began and if it was to harden their planes to nuclear blasts. I think the consensus was they just didn't have the technology and the chips and transistors to keep up with the West and when they did they moved over from tubes. The jet bodies themselves should have been good protection. Russia is still the biggest producers of tubes.

 

[k6cpo]

Living in a city with as much military as San Diego has, I figure we're prime targets. I doubt I'm going to be around to worry about EMP if someone lobs a nuke at us.

 

[trentbob]

Living in a city with as much military as San Diego has, I figure we're prime targets. I doubt I'm going to be around to worry about EMP if someone lobs a nuke at us.

Yeah I guess that is food for thought, I don't know how many people know this but Russia's nuclear deterrent forces are at the highest state of readiness which would be equivalent to SAC being at Defcon 1. So we will just hope that everybody is careful, very, very careful...

 

[prcguy]

Ammo boxes do not make good EMP proof storage containers since there is a very poor connection between the box and top. In fact, some ammo boxes are waterproof with an O ring seal which insulates most of the lid. A good EMP box will have a steel layer to shield from the magnetic pulse then an insulator then a copper layer for the electric/RF pulse with lots of conductive fingers around the opening to make complete contact around the perimeter.

Some tube type radios and some specific military solid state radios can survive an EMP event.

 

[Lauri-CoyoteFrostbite]

".......I wish you were sitting at my table at the hamfest I was at this past Saturday...."


Thank you for the nice compliment, but I am sure that would have been a real downer when it came to EMP's. For a good part of my career (I am now blissfully retired)-- they were part of my gestalt,,,,, but I should probably back step a bit...

We hear a lot about 'EMP"s"- but what are they exactly ? I'll put their physics in terms of a nuclear weapon-

The energy 'pulse' is formed by the gamma radiation from a nuclear explosion— High-energy electrons are produced in the heart of that explosion when gamma rays collide with air molecules --that creates both positive and negative charges in the air. The lighter, negatively charged electrons are separated and dispersed. leaving the heavier, positively charged molecules behind. A large electrical field difference results. The differences in this electric field are caused by variations in air density and this results in time-varying electrical currents -- its these varying currents that produce the EMP.
Think of being inside a huge capacitor and the destructive high voltages and currents that exists between its plates.

That's the science behind the 'pulse'- but what do you, or I, do about it ? Un-classified studies today show that a thermonuclear burst of 20 mega tonnes 250 miles above Kansas will destroy practically all the electronic devices and electrical grid transformers in the US and most of Canada. The infrastructure will be gone..... we will be back in the 18th century.
I really don't have any answers- As far as Faraday shields etc. go- ? well, you can trust in them and hope we never get to prove them one way or another.
Sorry guys ------

A bit of colour for a back ground....
My grandfather, whom I speak of frequently in here, was an Air Force Special Weapon's Officer (AFSWO)- He had been an 8th Air Force B24 bombardier in WW2-and he knew death on an awesome scale with the push of his buttons. He joined the new USAF when it formed after the war--- as an 'observer' (euphemism for the bombardier in the new Strategic Air Command) -- he was one who flew in B36's right up to Russian air space during the Korean war to remind them that we meant business and to stay out of Korea. He only mention to the family later that he- literally- had his finger on a 20 mega tonne hydrogen bomb. Asked what would have happened if it were dropped- my mother said he would just go silent with a far away look in his eyes.

So today his fancy-pants grand daughter with her physics degrees and all her cleverness just remembers this quiet gentle man--- and she too has no answers,
_________________________________________________





....Well, that's not my style... I have to leave here with something said.

So---- I have 3 movies to suggest-
Dr. Strangelove or: How I Learned to Stop Worrying and Love the Bomb,
The Road,
The Day after

And this real neat book- (its everything you wanted to know about the 'devices' but didn't know where to look...available on Amazon)

Reflections of a Nuclear Weaponeer
by Frank H. Shelton


Sweet Dreams, Guys !!


Lauri

 

[trentbob]

".......I wish you were sitting at my table at the hamfest I was at this past Saturday...."


Thank you for the nice compliment, but I am sure that would have been a real downer when it came to EMP's. For a good part of my career (I am now blissfully retired)-- they were part of my gestalt,,,,, but I should probably back step a bit...

We hear a lot about 'EMP"s"- but what are they exactly ? I'll put their physics in terms of a nuclear weapon-

The energy 'pulse' is formed by the gamma radiation from a nuclear explosion— High-energy electrons are produced in the heart of that explosion when gamma rays collide with air molecules --that creates both positive and negative charges in the air. The lighter, negatively charged electrons are separated and dispersed. leaving the heavier, positively charged molecules behind. A large electrical field difference results. The differences in this electric field are caused by variations in air density and this results in time-varying electrical currents -- its these varying currents that produce the EMP.
Think of being inside a huge capacitor and the destructive high voltages and currents that exists between its plates.

That's the science behind the 'pulse'- but what do you, or I, do about it ? Un-classified studies today show that a thermonuclear burst of 20 mega tonnes 250 miles above Kansas will destroy practically all the electronic devices and electrical grid transformers in the US and most of Canada. The infrastructure will be gone..... we will be back in the 18th century.
I really don't have any answers- As far as Faraday shields etc. go- ? well, you can trust in them and hope we never get to prove them one way or another.
Sorry guys ------

A bit of colour for a back ground....
My grandfather, whom I speak of frequently in here, was an Air Force Special Weapon's Officer (AFSWO)- He had been an 8th Air Force B24 bombardier in WW2-and he knew death on an awesome scale with the push of his buttons. He joined the new USAF when it formed after the war--- as an 'observer' (euphemism for the bombardier in the new Strategic Air Command) -- he was one who flew in B36's right up to Russian air space during the Korean war to remind them that we meant business and to stay out of Korea. He only mention to the family later that he- literally- had his finger on a 20 mega tonne hydrogen bomb. Asked what would have happened if it were dropped- my mother said he would just go silent with a far away look in his eyes.

So today his fancy-pants grand daughter with her physics degrees and all her cleverness just remembers this quiet gentle man--- and she too has no answers,
_________________________________________________





....Well, that's not my style... I have to leave here with something said.

So---- I have 3 movies to suggest-
Dr. Strangelove or: How I Learned to Stop Worrying and Love the Bomb,
The Road,
The Day after

And this real neat book- (its everything you wanted to know about the 'devices' but didn't know where to look...available on Amazon)

Reflections of a Nuclear Weaponeer
by Frank H. Shelton


Sweet Dreams, Guys !!


Lauri

Wow oh, thanks for being part of a thread I'm in. Of the movies that you suggested, the day after is pretty compelling even though it's so old it has no relevance to today and has been hacked up and shared with other productions. Dr. Strangelove? Give me a break.

The one movie you didn't suggest is Fail-Safe. Henry Fonda, The Matador. That was the perfect solution to a mistake that ended the madness. Do you agree?

Thanks for the engagement, however limited, I look forward to anything you have to offer... You really should come back... really

 

[GlobalNorth]

There is no such thing as EMP immunity. Assuming we are referring to the HANE [High Altitude Nuclear Effects] from an nuclear explosion at ~ 100 km AGL, the event will create a large number of free electrons that degrade RF systems, contingent upon band. Specific impacts on RF systems include RF noise, mean path effects, and scintillation of signals [contingent upon bandwidth].

Even in military aircraft specifically engineered and built for resistance such as the E-4B and the E-6B, HQs, and other sensitive electronic environments; the effects are contingent upon distance, magnitude, type of emitting device, and other factors.

 

[vagrant]

I don‘t know about anyone else, but if you think the bands are dead now….

Still…I enjoy the art of QRP, so I am an optimist to some degree. Just do not expect me to work a contest.

 

[Omega-TI]

Okay, say for a second you have a tube radio that was buried and protected from an EMP. What are you going to power it with? It's a good bet the power grid will be down, and 99.99% of other radios nearby will be off-the-air. So, if you're lucky enough to have a 1972 Dodge Dart with points and no electronics under the hood, great, but how long is your gasoline gonna hold out?

 

[AB4BF]

Ammo boxes do not make good EMP proof storage containers since there is a very poor connection between the box and top. In fact, some ammo boxes are waterproof with an O ring seal which insulates most of the lid. A good EMP box will have a steel layer to shield from the magnetic pulse then an insulator then a copper layer for the electric/RF pulse with lots of conductive fingers around the opening to make complete contact around the perimeter.

Some tube type radios and some specific military solid state radios can survive an EMP event.

They do make good shields. There is a detachable hinge on one end (metal) and a pressure latch (metal) on the other end. All .30 caliber and .50 caliber boxes are water resistant as long as the seal is intact. I'll take pictures of mine tomorrow since they're down at my shop to show you if you have never seen one before...

ETA: I hope and pray we never ever have to find out how well ammo boxes, faraday cages or anti emp enclosures work - or not...

 

[prcguy]

I have a number of these ammo boxes and they are good for storage but don't meet much of any criteria as a survivable enclosure for electronics during an EMP event. You can find examples of EMP resistant enclosures on the Internet which have been tested and its a lot more complicated than just a steel box with no electrical continuity around its lid.

They do make good shields. There is a detachable hinge on one end (metal) and a pressure latch (metal) on the other end. All .30 caliber and .50 caliber boxes are water resistant as long as the seal is intact. I'll take pictures of mine tomorrow since they're down at my shop to show you if you have never seen one before...

ETA: I hope and pray we never ever have to find out how well ammo boxes, faraday cages or anti emp enclosures work - or not...

 

[Go-West]

I have a pacemaker that I had put on me in November 2004. I have heard from reasonable people tell me that I will drop dead suddenly now. I can accept this now in 2022 now as it stops running there.

 

[GlobalNorth]

I have a pacemaker that I had put on me in November 2004. I have heard from reasonable people tell me that I will drop dead suddenly now. I can accept this now in 2022 now as it stops running there.

You either have a plutonium powered device [unlikely] or a demand-only pulse generator device that uses power when needed.

 

[GlobalNorth]

Most Amateur bands would be either dead from hours to perhaps a day or more depending on variables such yield, frequency, mean path effects, height of burst, and the ionosphere's status . ELF and VLF are effectively unaffected. LF, MF, HF, VHF, and parts of the UHF bands would be most stricken, while parts of the UHF and the SHF, along with EHF would be unaffected.

 

[trentbob]

Okay, say for a second you have a tube radio that was buried and protected from an EMP. What are you going to power it with? It's a good bet the power grid will be down, and 99.99% of other radios nearby will be off-the-air. So, if you're lucky enough to have a 1972 Dodge Dart with points and no electronics under the hood, great, but how long is your gasoline gonna hold out?

If you were lucky enough to have a 72 Dart with points and no electronics you would have plenty of gas, just use your rubber hose on any other intact car, the big question would be, how long are YOU going to last with radiation poisoning

 

[AK9R]

Un-classified studies today show that a thermonuclear burst of 20 mega tonnes 250 miles above Kansas will destroy practically all the electronic devices and electrical grid transformers in the US and most of Canada.

I think that's the piece most folks don't consider. It's not just the semiconductor junctions and thermionic valves, which are the basis of all electronic switching and amplification, that will be destroyed. It's the transformers. Our whole world of electricity and electronics is dependent on transformers. If an EMP shorts out the windings in every transformer in the blast area, we are quite literally screwed.

 

[AK9R]

I think you all are missing something about the 1972 Dodge Dart with Kettering (points) ignition.

A Kettering ignition depends on a coil, i.e. a transformer. When the points open, the field in the coil (transformer) collapses which generates a high enough voltage to jump the gap in the spark plug which ignites the fuel-air mixture, and so forth. If an EMP takes out transformers, as Miss Lauri suggests, then the coil in your '72 Dart will be toast.