Shortwave radios and EMP

[wizardb]

I've just finished a novel written around an EMP attack on the USA. Very interesting and certainly food for thought. In the course of the story they finally found a working shortwave radio (obviously battery operated) and received news of what had happened from out of the country broadcasts. With mideast countries and korea developing nuclear energy, I believe there is a good chance of an EMP attack becoming a reality in the not too distant future. My question is--will the current battery operated shortwave radios (with PLL conversion, etc.) continue to work. Or should one have an older battery operated shortwave radio and if so what do you suggest. I currently use a Grunding G8 taveller II and I have a Tecsun PL-390 coming this week. Don't know what I'll have a month from now--would like to look at a Satelit 750 or 800 somewhere down the road. I'm not fanatical about this but I would like to hear your thoughts and comments. Hope this is posted in the right place.

 

[Pape]

my understanding of emp and such and modern electronic make me think of good lock to find emp protected commercial stuff.


Best bet is get / make your self a faraday box / cage and make sure no antenna lead in to it unless you're using the device.

 

[WouffHong]

Emp

I've just finished a novel written around an EMP attack on the USA. Very interesting and certainly food for thought. In the course of the story they finally found a working shortwave radio (obviously battery operated) and received news of what had happened from out of the country broadcasts. With mideast countries and korea developing nuclear energy, I believe there is a good chance of an EMP attack becoming a reality in the not too distant future. My question is--will the current battery operated shortwave radios (with PLL conversion, etc.) continue to work. Or should one have an older battery operated shortwave radio and if so what do you suggest. I currently use a Grunding G8 taveller II and I have a Tecsun PL-390 coming this week. Don't know what I'll have a month from now--would like to look at a Satelit 750 or 800 somewhere down the road. I'm not fanatical about this but I would like to hear your thoughts and comments. Hope this is posted in the right place.

In a paragraph, EMP will fry all electronics internally within the zone of exposure thereto. As mentioned, one would have to "harden" the equipment, as the military has been and still is doing, in order to have electronics survive the Electromagnetic Pulse. If of small rise time and high peak, it will also effect equipment from the proverbial "DC to Daylight" frequency range that may be hardened (per se) but have an antenna still attached and not protected.

Wouff (Retired NASA EMC Systems Eng'r)
TEMPEST-FIXIT, NON-TEMPEST- FUGIT (VBG) :roll:

 

[wizardb]

Thanks for your replies so far. This is an interesting subject and I think I'll read some factual information on EMP just to satisfy myself. Not sure how accurate the inofrmation was in the novel I read but it seems pretty much on the mark.

 

[z96cobra]

What's the title of the book? Was it any good?

 

[wizardb]

The book is One Second After by William R. Forstchen. I'm listening to it as an Audio book. It evolves around a community in South Carolina and all the changes that take place after the EMP hits..Mostly about survival. I'm not quite through with it yet but it does make one think. I think its a very good book.

 

[Token]

Maybe you should visit a few prepper forums, this is a topic often discussed there

EMP is an often misunderstood effect. On one hand you have people who are unfamiliar that such a thing is possible and would say there is nothing to fear, and on the other you have people incorrectly assuming a single high level EMP device will kill all electronics in the US. The truth is someplace in the middle. Also, the results are VERY arguable, models show from extreme damage to every electronic device to moderate damage to a portion of the devices.

A HEMP (High-altitude Electro Magnetic Pulse) will effect a large are, a SREMP (Source Region Electromagnetic Pulse) will effect a specific region. The SREMP will be much more devastating to general electronics while the HEMP will be more effective against infrastructure.

Past studies have shown that a single HEMP detonated 250 miles above Kansas would have some impact on electronics across the entire continental US. While some low level electronics (radios, computers, the computer that runs your car, air traffic control systems, etc) closely centered under the device would be affected the majority of the impact across the rest of the nation would be felt to power distribution systems, telephones, data lines, etc.

In a simplified way you can look at it like this, the HEMP typically effects things connected to large area conductors. Large area conductors are things like the power grid, telephone lines, data lines (non-fiber), and large antennas. The larger the area the conductor covers the more current that will be generated. The current has to have someplace to go, and things connected to the conductors make a nice place for the current to go. So that a light bulb plugged into the AC socket in your house might be killed, but the spare light bulb in the kitchen drawer will not. The radio connected to a large external antenna might suffer a damaged front end (the closer to centered under the device the more likely), while the one not connected to anything and setting on the bench probably will not.

A good specific example of this would be the 250 mile altitude 1.4 MT nuclear test done above Johnston Island in 1962 (Starfish Prime, part of Operation Fishbowl). This test damaged infrastructure related hardware (street lights, telephone systems, etc) as far away as Hawaii (about 900 miles), but the impact was relatively minor, some street lights (about 300 total) needed to be replaced, fuses blew in a few houses, and a telephone microwave link needed to be repaired. There is no reported damage to ham radio gear or similar equipment, despite many of them being in actual use at the time of the EMP. Nor have I heard or read that any radio gear was damaged on ships and islands closer to the device.

Because of variations in the magnetic fields around the world a similar device centered over Kansas would cause higher pulse levels, and likely more damage. The Russians did the most applicable testing, their magnetic situation being similar to the US. They popped a 300 kT device at 180 miles over Khezkazgan in Khazakstan (Test 184, or K-3). EMP damage within 600 miles was significant, with power distribution systems catching fire and radars being disabled. Radios were damaged, to varying degrees, out to about 400 miles.

A SREMP would be detonated at a much lower altitude, and effect a smaller area. But, the impact to individual devices would be much more devastating. A single SREMP has the potential to destroy essentially all solid state based and unshielded electronics for several hundred miles, but the damage fades quickly outside that high impact area.

Shielding does NOT have to be all that high tech. A closed and sealed metal ammo can, for example, probably provides enough shielding that a solid state device would not be affected within a pretty close range to the SREMP. Of course, you cannot use the device while it is in the can, the antenna lead would have to pierce the shielding.

People will talk about “hardening” electronics against EMP. People will talk about the fact that tube gear is naturally a bit “harder” in this aspect. The fact is probably that a close EMP will kill those portables you mention…but what is meant by close really is hard to define.

This whole subject is often debated. Science can support a lot of different viewpoints on it. There are a lot of places you can find printed material that claims a single device will kill all radios in the US...but they never seem to quote the science behind why they say that. And the people who really know are not going to talk about it

T!

 

[jackj]

Another point is that not all kinds of electronics will be affected to the same degree. A solid state shortwave receiver might be rendered unusable while an older, tube type shortwave receiver won't be damaged at all. Tubes are much more immune to that type of damage than transistors. That's why the USSR's fighter planes used tubes in their radios and radars, they would be serviceable after a nuke attack while ours might not.

But you don't have to "harden" your receivers for them to survive an EMP. If the antenna isn't connected and the receiver isn't plugged in then the chances of damage are greatly reduced.

 

[wizardb]

Thanks again for all the interesting information. As I figured, alot of what hapened in the novel was written without knowledge and was ovviously meant for entertainment. But you now thats how misconceptions are formed. I had thought about posting my question for a few days because I didn't want to sound like an idiot. I'm glad I went ahead with the intial post as the information you guys have presented is very interesting.

 

[Token]

Another point is that not all kinds of electronics will be affected to the same degree. A solid state shortwave receiver might be rendered unusable while an older, tube type shortwave receiver won't be damaged at all. Tubes are much more immune to that type of damage than transistors. That's why the USSR's fighter planes used tubes in their radios and radars, they would be serviceable after a nuke attack while ours might not.

As I said in my post, “People will talk about the fact that tube gear is naturally a bit “harder” in this aspect.” But in reality this is not necessarily so, or at least not a large advantage. Yes, if a receiver is all tube with no semi-conductors, including no solid-state diodes, then it is possibly a bit more naturally resistant than a solid-state device. But many tube type receivers have low voltage capacitors and solid-state diodes in them, both subject to failure at field levels lower than the tubes themselves will easily survive. It is the system that has to be looked at as a whole, not just tube vs solid-state. In fact, in US Mil testing the all solid state PRC-77 was more survivable in an EMP situation than the partially tube PRC-25 it was derived from.

The Russians found this out in the same Khazakstan test I mentioned before, when they had mass failures in diesel generator sets that had NO solid-state devices at all, their control electronics was all tube.

As for EMP resistance being the reason for the USSR to continue using tubes (in everything that they could, not just in fighters) long after the West switched to solid-state, this is something that has been claimed often in the past, and may have even played some small part at some level in the decision. It is claimed in book after book on the subject, but they never get around to identifying the source of the claim. Finding documented proof that this had more than a very minor bearing on the continued use of tubes is pretty much impossible, at least I have never seen it and I have indeed looked for it. I suspect it was a perceived plus, but not THE reason to continue using tubes.

During the Cold War the Soviets often ran between 2 and 10 years behind the West in technology, depending on the exact technology being discussed. But, this was at the cutting edge of technology, not in average application. And I am not talking theory here, the Russians have always had World Class aeronautical engineers and mathematicians, I am talking about real working hardware, getting the ideas out and in the flesh. In large-scale front line applications the technology was more like 10 to 20 years behind. Think about the last fighters introduced before the MiG-29, say the MiG-25. This was the last generation to use tubes extensively.

Looking specifically at the MiG-25 it was designed in the very early 60’s, and first flew in 1964. It entered service in 1970. If the tech was indeed 10 years behind the West and comparing it to a US fighter being tested in the early 50’s and entering service in 1960 you would find the US fighter also using tubes to a great extent. But, the MiG-29, designed and built long before the end of the Cold War and still facing the same potential EMP issues, is pretty much all solid state except in areas were tubes make more sense…such as the final amplifier in high power RF applications.

But, there is even more to the issue than just a tech lag. There is also the tech inertia and social and economic issues.

The Russians had lots of people to build tube-based stuff, and it kept that lot of people busy. Solid-state production is much more automated. Not only did it require an investment in technical training and production capability but it actually reduced the number of people required to support the industry. The US had the consumer base clammering for electronics goodies to offset those investments, and to increase the required production beyond just the needs of the military. The average Russian on the street was happy to get toilet paper regularly and have food to eat, a new solid-state color TV was far down the list of got-to-haves.

But you don't have to "harden" your receivers for them to survive an EMP. If the antenna isn't connected and the receiver isn't plugged in then the chances of damage are greatly reduced.

This is probably true in the event of a HEMP and you not being directly under the device, but is most definitely not the case with a SREMP. In the situation of a SREMP and being n the targeted region the runs on the circuit boards themselves will build the current needed to destroy devices. Placing the electronics in question inside a shielded box of some type should reduce this impact significantly.

T!