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eHam Forums => RFI / EMI => Topic started by: WA2ISE on September 23, 2017, 01:33:19 PM



Title: EMP from North Korea's nuke over the Pacific, would it damage radios?
Post by: WA2ISE on September 23, 2017, 01:33:19 PM
Heard that nuke bombs can produce electromagnitic pulses(?) that can fry the front ends of radios.  I don't know if this is just an urban legend, or if it's a real problem (assuming N Korea actually launches an H bomb and blows it up over the Pacific, as they mentioned thinking of doing...).  Many other problems this would cause would be far more serious, like all that radioactive crap let loose in the air.  Power companies might not handle it well, either.  (I'm talking about places far enough away that are not vaporized by a direct hit).  Cars' electronics might not like it either.  Even if you kept an old 2m HT stashed away in a metal sealed box, you couldn't charge its batteries if the power company and your car are dead...  

I doubt that NK would actually do it,  ???  



Maybe make sure your tinfoil hats are well grounded.   ;D  


Title: RE: EMP from North Korea's nuke over the Pacific, would it damage radios?
Post by: W1VT on September 23, 2017, 03:10:55 PM
http://www.arrl.org/lightning-protection
There is a 4 part series that discusses the physics involved, as well as mitigation strategies, on the ARRL's Lightning Protection Web Page.
Electromagnetic Pulse and the Radio Amateur - Part 1
QST August 1986, pp. 15-20, 36
Will your station survive the effects of lightning strikes ........
Electromagnetic Pulse and the Radio Amateur - Part 2
QST September 1986, pp. 22-26
...testing EMP/transient-protection devices
Electromagnetic Pulse and the Radio Amateur - Part 3
QST October 1986, pp. 38-41
...protectors are connected to Amateur Radio equipment and retested.
Electromagnetic Pulse and the Radio Amateur - Part 4
QST November 1986, pp. 30-34
What can be done to protect an Amateur radio station from lightning......
Feedback: QST February 1987, p. 43
Feedback: QST April 1987, p. 59
The model number of the Siemans spark gap is B1-A350, not BI-A350.


Title: RE: EMP from North Korea's nuke over the Pacific, would it damage radios?
Post by: KC4ZGP on September 23, 2017, 04:51:19 PM
Rocket Man said he'll detonate an H-bomb over the Pacific ocean.

What is the world waiting for? What will it take now for any country to act?

Here's what I figure, If South Korea and U.S. forces just plowed northwards,

half the North Korean soldiers will not be poised in fire-when-ready position.

Their arms will be straight up...please save us from this ____.

The other half of the North Koran army will holding up the arms of the first half
because they're too weak from starvation to hold up their own arms.

Kraus



Title: RE: EMP from North Korea's nuke over the Pacific, would it damage radios?
Post by: K0UA on September 23, 2017, 05:37:07 PM
Heard that nuke bombs can produce electromagnitic pulses(?) that can fry the front ends of radios.  I don't know if this is just an urban legend, or if it's a real problem (assuming N Korea actually launches an H bomb and blows it up over the Pacific, as they mentioned thinking of doing...).  Many other problems this would cause would be far more serious, like all that radioactive crap let loose in the air.  Power companies might not handle it well, either.  (I'm talking about places far enough away that are not vaporized by a direct hit).  Cars' electronics might not like it either.  Even if you kept an old 2m HT stashed away in a metal sealed box, you couldn't charge its batteries if the power company and your car are dead...  

I doubt that NK would actually do it,  ???  



Maybe make sure your tinfoil hats are well grounded.   ;D  


I reckon you haven't heard of Starfish Prime?  In 1962?  EMP is real.  And I would't trust NK with a firecracker.
Also nuclear weapons can be "tailored" to produce more EMP.  EMP could be more dangerous than the blast itself and kill far more people over time.  No electricity means no infrastructure.  Back to the 1800's.  How many of us can live back in the 1800's.  Some, but not all.

You can read about Starfish Prime here:
https://en.wikipedia.org/wiki/Starfish_Prime

Starfish Prime caused an electromagnetic pulse (EMP), which was far larger than expected, so much larger that it drove much of the instrumentation off scale, causing great difficulty in getting accurate measurements. The Starfish Prime electromagnetic pulse also made those effects known to the public by causing electrical damage in Hawaii, about 1,445 kilometres (898 mi) away from the detonation point, knocking out about 300 streetlights,[6] setting off numerous burglar alarms and damaging a telephone company microwave link. The EMP damage to the microwave link shut down telephone calls from Kauai to the other Hawaiian islands



Title: RE: EMP from North Korea's nuke over the Pacific, would it damage radios?
Post by: K0UA on September 23, 2017, 05:49:28 PM
Oh, by the way, you don't need a nuclear bomb to make an EMP generator either.  Nope, its pretty easy.  But you do need the ability to launch things high up.  Hmm  lets see NK already has that ability. 

https://en.wikipedia.org/wiki/Explosively_pumped_flux_compression_generator


Title: RE: EMP from North Korea's nuke over the Pacific, would it damage radios?
Post by: KB2WIG on September 23, 2017, 07:42:31 PM


This guy can't produce a viable nuke, so don't worry about an H bomb.

As far as the "EMP" problem, please consider the inverse square law.

More than likely, with more saber rattling from N.K., Japan will produce their own atomic devise and then tell the Fat mMan, er , the Rocket Man, where to go.

The JA's have reactors, and the expertise to produce their own material.


klc


Title: RE: EMP from North Korea's nuke over the Pacific, would it damage radios?
Post by: K0UA on September 24, 2017, 07:03:21 AM


This guy can't produce a viable nuke, so don't worry about an H bomb.

As far as the "EMP" problem, please consider the inverse square law.

More than likely, with more saber rattling from N.K., Japan will produce their own atomic devise and then tell the Fat mMan, er , the Rocket Man, where to go.

The JA's have reactors, and the expertise to produce their own material.


klc

Why would you say he can't produce a viable nuke when he has already produced several viable nukes, and possibly already produced an H bomb?  We are not sure on the last one, but most believe the capability to produce an H bomb if not already here is very near.  Don't underestimate the fat kid's and his country's ability to wage war. And while I agree that Japan has the expertise and the means to produce nukes, do they have the will?  The gunfight doesn't' always go the the fastest or even the most accurate.  It often goes to the most willing.  Nuclear warfare may come down to "the most willing".  I don't know if the fat kid is willing or not for sure, but do you want to bet the farm on it? 


Title: RE: EMP from North Korea's nuke over the Pacific, would it damage radios?
Post by: ND6M on September 24, 2017, 11:45:13 AM


This guy can't produce a viable nuke, so don't worry about an H bomb...

Define "nuke"
He already HAS detonated multiple Fission bombs.
I doubt that he has the technology to detonate a Fusion bomb,.......... yet.

I lived in Japan for many years, and I'm of the opinion that they have no desire to become a nuclear bomb capable nation.


Title: RE: EMP from North Korea's nuke over the Pacific, would it damage radios?
Post by: K0UA on September 24, 2017, 01:17:55 PM


This guy can't produce a viable nuke, so don't worry about an H bomb...

Define "nuke"
He already HAS detonated multiple Fission bombs.
I doubt that he has the technology to detonate a Fusion bomb,.......... yet.

I lived in Japan for many years, and I'm of the opinion that they have no desire to become a nuclear bomb capable nation.

Well, I don't doubt for a moment he either already has detonated an H bomb or will soon. We have constantly since the beginning underestimated the capabilities and the will of NK.  I agree with you that Japan does not have the will to make atomic weapons, even if they have the capability to easily do so.  I also believe while the South Korean military is extremely capable, they are governed now by a pacifist government.  Not a good unified front in standing down the aggressive little fat boy.


Title: RE: EMP from North Korea's nuke over the Pacific, would it damage radios?
Post by: KJ4HVL on September 25, 2017, 08:36:46 AM
EMP induces current into circuits. Many IC's are rated to withstand thousands of volts of ESD. How long of a wire do you need to generate 2KV?

The only items that will be damaged are those with high imedance inputs, and / or very long wires on one side and ground on the other.

The transmission grid is hardened against this (especially north of mason / dixon line) thanks to a better understanding of solar storms. Local distirbution is not.
Most of the other systems that you would be worried about are floating and won't see a large enough field at their locations to cause damage across the case, unless they are within about 60 - 100 miles of the blast, in which case there are other more grave concerns.

Your radio's weakest links will be the long-wire + balun combo many of us use, and the power / control side.
A completely disconnected radio stashed in the corner of your basement is probably fine. In an ammo-can even better. No additional special precautions are required, unless you plan on it going off down the block.


Title: RE: EMP from North Korea's nuke over the Pacific, would it damage radios?
Post by: KC4ZGP on September 25, 2017, 10:39:13 AM

We did WWII backwards. We should have sided with Hitler, crush the Soviet union then crush Hitler.

In the Pacific, side with the Japanese, crush China then crush Japan.

We would own zie verld.

Kraus


Title: RE: EMP from North Korea's nuke over the Pacific, would it damage radios?
Post by: KH6AQ on September 25, 2017, 11:56:37 AM
MIL-STD-188-125-1 provides design parameters for EMP hardened equipment. Also see MIL-HDBK-423.

The E-field level to design antenna systems to is 50kV/m. http://ema3d.com/high-altitude-electromagnetic-pulse-hemp-emp-simulation/

The question "How long of a wire do you need to generate 2KV?" For an open-circuit monopole the wire length would be 3.7 cm or 1.5 inches.


Title: RE: EMP from North Korea's nuke over the Pacific, would it damage radios?
Post by: AF6LJ on September 25, 2017, 11:58:34 AM

We did WWII backwards. We should have sided with Hitler, crush the Soviet union then crush Hitler.

In the Pacific, side with the Japanese, crush China then crush Japan.

We would own zie verld.

Kraus
I disagree;
We should have stayed out of it, became a refuge for jews from Europe, developed the bomb and nuked anybody who dared cross our borders.


Title: RE: EMP from North Korea's nuke over the Pacific, would it damage radios?
Post by: VK2LEE on September 26, 2017, 06:53:13 AM
Probably if You happened to live in the Pacific, but radiation fallout would be the major problem, I believe.
For those who Don't believe the little fat bloke can or would explode bombs [Nukes??] outside their airspace....
Just Remember that North Korea can easily be seen [or unseen] from the International Space station at night because of the lack of light , as they do NOT have electricity because the Generators don't operate 24 hours a day.  So You have a country with many people starving with their leader spending Millions on Weapons and the armed forces. He seems to be trying to make Himself heard around the world. Who knows what He is thinking??
I also agree that Japan is a pacifist country and don't wish to attack anyone or any country. I believe it against their Law. Self protection only. So. if they have North Korean missiles exploded in their air space.... the self protection part may have to be turned ON...

Lee  VK2LEE


Title: RE: EMP from North Korea's nuke over the Pacific, would it damage radios?
Post by: K0UA on September 26, 2017, 06:58:38 AM
MIL-STD-188-125-1 provides design parameters for EMP hardened equipment. Also see MIL-HDBK-423.

The E-field level to design antenna systems to is 50kV/m. http://ema3d.com/high-altitude-electromagnetic-pulse-hemp-emp-simulation/

The question "How long of a wire do you need to generate 2KV?" For an open-circuit monopole the wire length would be 3.7 cm or 1.5 inches.

So If I have this right, it would take a very short piece of wire to develop voltages that would kill an IC , correct?


Title: RE: EMP from North Korea's nuke over the Pacific, would it damage radios?
Post by: AF6LJ on September 26, 2017, 07:25:38 AM
MIL-STD-188-125-1 provides design parameters for EMP hardened equipment. Also see MIL-HDBK-423.

The E-field level to design antenna systems to is 50kV/m. http://ema3d.com/high-altitude-electromagnetic-pulse-hemp-emp-simulation/

The question "How long of a wire do you need to generate 2KV?" For an open-circuit monopole the wire length would be 3.7 cm or 1.5 inches.

So If I have this right, it would take a very short piece of wire to develop voltages that would kill an IC , correct?
It's more complicated than that.
The current is very low, capacitance in the circuit will absorb much of the energy, many factors are at play.


Title: RE: EMP from North Korea's nuke over the Pacific, would it damage radios?
Post by: KH6AQ on September 26, 2017, 08:40:43 AM
Take a look at this NEMP simulator.   http://morens.co.kr/board/upload/nemp_systems_ts_nemp.pdf


Title: RE: EMP from North Korea's nuke over the Pacific, would it damage radios?
Post by: AF6LJ on September 26, 2017, 08:49:44 AM
50KV per meter squared isn't much energy and we need to remember that in an actual nuclear explosion the emp energy decreases at the rate of one ninth every time the distance from the device is doubled.
If a receiver has a DC short on the input or the antenna presents a DC short the effects of the EMP entering from the input side of the receiver are almost nullified.
The real danger is and always has been due to long lines, power telephone and long / large antennas, with the notable exception of AM broadcast radios the ferrite loop antenna contained therein would potentially couple enough energy to damage the radio. .


Title: RE: EMP from North Korea's nuke over the Pacific, would it damage radios?
Post by: KD0REQ on September 26, 2017, 08:50:20 AM
the most critical element is the grid.  if the grid survives, we can make more stuff, pump more water, process more food.

no grid, no milking machines, computers, water works, Tesla cars, broadcasting, military base readiness, gas and diesel pumps on the corner ....

it basically comes down to will the transformer insulation puncture, insulators carbon-track, relays fail, SmartGrid control systems fizzle out. EMP is a widespread multiple lightning strike, all at once. we will be in deep doo.

oh, and there is no Big Chief over power distribution and generation to pick up the phone and say, "fix this now, hang the cost, for tomorrow the Norks may test us."



Title: RE: EMP from North Korea's nuke over the Pacific, would it damage radios?
Post by: AF6LJ on September 26, 2017, 09:25:32 AM
the most critical element is the grid.  if the grid survives, we can make more stuff, pump more water, process more food.

no grid, no milking machines, computers, water works, Tesla cars, broadcasting, military base readiness, gas and diesel pumps on the corner ....

it basically comes down to will the transformer insulation puncture, insulators carbon-track, relays fail, SmartGrid control systems fizzle out. EMP is a widespread multiple lightning strike, all at once. we will be in deep doo.

oh, and there is no Big Chief over power distribution and generation to pick up the phone and say, "fix this now, hang the cost, for tomorrow the Norks may test us."
There is no lightning involved; you are right about the grid, I would hope that our government would have the good sense to warn power companies of an inbound nuke. They could shut down the grid, open relays and potentially save a lot of hardware from damage.




Title: RE: EMP from North Korea's nuke over the Pacific, would it damage radios?
Post by: KH6AQ on September 26, 2017, 10:06:49 AM
This Montena technical note points out the the E-field during IEC 61000-4-2:2008 ESD testing is similar to that of a NEMP event. See 3.2, Comparison with ESD.

http://www.montena.com/fileadmin/technology_tests/documents/technical_notes/TN17F_Safe_distance_NEMP.pdf

I believe the 50 kV/m used for NEMP design is assumed to be at ground level, far from the nuclear event. BTW, in free space the E-field decreases linearly with distance while the energy decreases as distance squared. Double the distance and the E-field is 1/2 while the energy is 1/4.

Wikipedia has an interesting article on this subject. https://en.wikipedia.org/wiki/Electromagnetic_pulse


Title: RE: EMP from North Korea's nuke over the Pacific, would it damage radios?
Post by: AF6LJ on September 26, 2017, 10:28:35 AM
This Montena technical note points out the the E-field during IEC 61000-4-2:2008 ESD testing is similar to that of a NEMP event. See 3.2, Comparison with ESD.

http://www.montena.com/fileadmin/technology_tests/documents/technical_notes/TN17F_Safe_distance_NEMP.pdf

I believe the 50 kV/m used for NEMP design is assumed to be at ground level, far from the nuclear event. BTW, in free space the E-field decreases linearly with distance while the energy decreases as distance squared. Double the distance and the E-field is 1/2 while the energy is 1/4.

Wikipedia has an interesting article on this subject. https://en.wikipedia.org/wiki/Electromagnetic_pulse

So we don't actually know critical details.
A friend is a nuclear engineer, we had a long discussion on this subject and tried to find out critical details  and it appears many of the critical details are ether not on the net or classified.

the EMP from a nuke is caused by the Compton Effect Neutrons ionize the atmosphere giving it an electrical charge.
This electrical charge while high in voltage potential is very low in current.

It would be nice to have all the data in order to form an educated guess as to what would happen. What we hear on the lamestream media is there to gather ratings and fear monger, I am sure of that.

I am not saying there is nothing to be worried about, I am saying I feel the threat is overstated.


Title: RE: EMP from North Korea's nuke over the Pacific, would it damage radios?
Post by: W9IQ on September 26, 2017, 11:13:20 AM
With regard to HEMP events, radios with no cords connected, no internal antennas, and with metal cabinets will probably not be affected at all. Cords, antennas, power lines, etc. will collect the EM energy from an HEMP event and therefore should ideally be disconnected from the radio to afford the best protection. By way of an example, an 80 meter HF antenna has the potential to generate a 1 MV signal. Incidentally, coax feedline provides superior EMP protection compared to ladder line due to its shielding of the center conductor from EMP events and due to its lower arc over voltage that provides a level of additional protection for any connected equipment.

Due to the very short pulse duration from an HEMP event, it is estimated that the energy at the ground level will be < 1 J/m2. This means than many typical transient protection products will not be destroyed by the event and may therefore provide reasonable protection if properly applied.

- Glenn W9IQ


Title: RE: EMP from North Korea's nuke over the Pacific, would it damage radios?
Post by: KH6AQ on September 26, 2017, 11:20:06 AM
Good information Glenn.

This white paper by PolyPhasor shows a range of NEMP voltages and currents for HF antennas. The range is 10kV to 1MV and 500A to 10kA. That's 5-10,000 megawatts. As a point of reference, an 8kV human body model discharge into a transceiver antenna port is 5 amps for roughly 100ns. The peak ESD power into a 50 ohm load is 1250 watts.  

http://www.transtector.com/SiteMedia/SiteResources/WhitePapersandTechnicalNotes/1485-041.pdf?ext=.pdf


Title: RE: EMP from North Korea's nuke over the Pacific, would it damage radios?
Post by: AF6LJ on September 26, 2017, 11:45:11 AM
With regard to HEMP events, radios with no cords connected, no internal antennas, and with metal cabinets will probably not be affected at all. Cords, antennas, power lines, etc. will collect the EM energy from an HEMP event and therefore should ideally be disconnected from the radio to afford the best protection. By way of an example, an 80 meter HF antenna has the potential to generate a 1 MV signal. Incidentally, coax feedline provides superior EMP protection compared to ladder line due to its shielding of the center conductor from EMP events and due to its lower arc over voltage that provides a level of additional protection for any connected equipment.

Due to the very short pulse duration from an HEMP event, it is estimated that the energy at the ground level will be < 1 J/m2. This means than many typical transient protection products will not be destroyed by the event and may therefore provide reasonable protection if properly applied.

- Glenn W9IQ
Agreed;


Title: RE: EMP from North Korea's nuke over the Pacific, would it damage radios?
Post by: AA4HA on October 10, 2017, 03:56:00 PM
Where it gets funky is in the fast rise times and that NEMP is not a single waveform;

The first and fastest waveform has a rise time of about 2 nSec and a duration of between 20 and 80 nSec. This is known as the "E1 waveform" and is potentially the most damaging to solid state electronics. The rise time is so fast that the lead lengths of transient suppressors and their trigger time (like with GDT's (gas tubes) has not even happened before the most energetic part of the E1 waveform has come and gone (up to 50 kV/m for close in). E1 is produced by the prompt-gammas of a detonation.. the gamma rays interact with the Earth's magnetic field and creates Compton electrons that bend and produce transverse currents.

E1 Waveform discussion;     http://www.eiscouncil.com/App_Data/Upload/9b03e596-19c8-49bd-8d4e-a8863b6ff9a0.pdf

As the E1 waveform is decreasing now the scattered gamma rays and gammas produced by neutron interactions are produced. This is known as the E2 pulse and can be several hundred milliseconds long.

Lastly is E3. This is a distortion of the Earth's magnetic field and can last for tens of seconds. It is a magnetohydrodynamic effect and can be the most problematic for long lines (telephone and power) and transformers in substations.
-----------
I had a client where this understanding was required for an electrical utility. We had to become familiar with the Oak Ridge report on the vulnerabilities of the electrical power grid.


Title: RE: EMP from North Korea's nuke over the Pacific, would it damage radios?
Post by: N8FVJ on October 13, 2017, 08:08:18 AM
The test was underground, no EMP was passed into the atmosphere plus it was on the other side of the earth.