Incoming CME, Released December 20, 2014

[RichardSinFWTX]

I've wondered about that.  I've seen it done in YouTube videos; but I can't help but wonder is it truly blocking the energy or is it just that the audio from the ringer isn't loud enough to be heard through the can/lid. 

I'll see if I can test the theory this weekend.

Stay tuned for the results.   8)

[gil]

If it rings, you don't have continuity, or it's not a good anti-EMP safe.

I tried that... Doesn't ring. It's not because it is in the can, I would hear it.
I do not know if it really means it's EMP safe though. I have seen a demo of a Faraday bag with a cell phone and it rang in the bag. The bag was placed in a microwave then... No damage to the phone.

Gil.

[cockpitbob]

Another fun one to try is put an HT on receive in the can.  That way you can blast it with a few watts up close.  Try both bands if you have a couple dual-band HTs.

[Quietguy]

The telephone test is actually a fairly good one - EMP frequencies are far below the operating frequency of a cell phone, so if the can stops cell phone frequencies it certainly should stop EMP frequencies.  In 1986 QST Magazine ran a four part series on EMP and its possible effects on amateur radio.  The author worked for the FedGov and ran tests using EMP simulators that showed ham gear pretty immune to EMP as long as nothing was connected to them to serve as an antenna for the EMP energy.  Their interest was in keeping MARS going, among other things.

Here is an excerpt:

From "Electromagnetic Pulse and the Radio Amateur - Part 1"
QST Mgazine, August 1986

The energy of a high-altitude EMP is spread over a major part of the RF spectrum.  Since the pulse has such a fast rise time and short duration, it covers a broad frequency range extending from 10 kilohertz to 100 megahertz.  The electric field strength remains fairly constant in the 10-khz to 1-MHz band; it decreases by a factor of 100 in the 1- to 100 MHz band and continues to decrease at a faster rate for frequencies greater than 100 MHz.  Most high altitude EMP energy is at frequencies between 100 kHz and 10 MHz, and 99% lies in the frequency spectrum below 100 MHz (Fig 5).

Wally

[raybiker73]

The telephone test is actually a fairly good one - EMP frequencies are far below the operating frequency of a cell phone, so if the can stops cell phone frequencies it certainly should stop EMP frequencies.  In 1986 QST Magazine ran a four part series on EMP and its possible effects on amateur radio.  The author worked for the FedGov and ran tests using EMP simulators that showed ham gear pretty immune to EMP as long as nothing was connected to them to serve as an antenna for the EMP energy.  Their interest was in keeping MARS going, among other things.

That's interesting! It would be cool to see a test done with modern equipment. I wonder if the newer rigs would hold up as well? I'm going to go dig into the QST archive and check this series out.

[Quietguy]

I wonder if the newer rigs would hold up as well?

I think probably so - there was a series of televised EMP tests a few years ago showing the effect on new automobiles, and they had to work hard to get a failure.  I don't remember the name of the program, but I saw a portion of the video.

CAUTION - UNPOPULAR OPINION FOLLOWS!

I believe there has been a lot of confusion (some of it deliberately propagated by the Fear Merchants) where EMP effects have been merged with ionizing radiation effects.  We hear EMP will kill chips - but EMP is a burst of static charge coupled with a very powerful radio wave. EMP = ElectroMagnetic Pulse = Radio Wave.  The radio wave will induce a voltage on a long wire (after all, that is what antennas do) and that voltage can fry a chip, just like any high voltage beyond the chip's rating.  But the chip itself should have internal conductor lengths that are truly microscopic compared to the frequency content of an EMP - 99% below 100 MHz.  Modern equipment is constructed with almost no interconnect wiring inside the case; it is mostly short PCB runs.  So equipment with no external connections like antenna, ground wire, headset cable, power supply cable, etc should do reasonably well.

However, ionizing radiation from a nuclear burst will kill chips and other electronics because of the hard radiation - but that is not what we have with an EMP.  It seems to me that if you have an incident where you are exposed to enough ionizing radiation to kill chips, you probably have more important things to worry about... or you likely will no longer be worried about anything at all.

So my opinion is practice good transient protection and treat your equipment like a lightning strike is eminent.  Disconnect your equipment when not in use and use transient voltage suppression devices where appropriate.  There are two flavors documented in the QST articles, one using MOVs for AC power protection and one using TVS diodes for things like antenna connections.  There are newer devices on the market too.  It costs very little to store your radios in a cookie tin or filing cabinet when not in use and it can't hurt - so why not?  But some people obsess over these things and I believe it takes away from more important issues... like figuring out where your water will come from if somebody dumps chemicals in your river.

Wally

[gil]

I wonder if the newer rigs would hold up as well?

While building kits, some chips and transistors you can't even touch without grounding yourself first... So, I'd say those would not make it though an EMP.

Gil.

[cockpitbob]

Quietguy, you've posted some really good stuff here. 

Regarding the ionizing radiation; I hadn't thought about that, but it makes a lot of sense and a harmful human dose won't be needed to kill our computerized radios.  All it takes is one hit by a high energy particle to flip a memory bit from 1 to 0.  I can easily see the case where our radios are not "damaged" but the program memory is scrambled rendering the radio useless.  I really need to get that Heathkit HW101 operational.

I really like the chart of EMP frequency content.  An EMI tight faraday cage should have no gaps or slots longer than 1/20 of a wavelength.  Since most of an EMP's energy is below 100MHz the doors to our faraday cages should make contact at least every 6".  A trash can with a tight lid will probably do that.  A metal cabinet won't without metal finger gaskets on the doors.

[cockpitbob]

Two are on the way.  Monday evening the sun gave a small burp in our direction and Wednesday it belched an X-class flair.  They'll arrive Friday and Saturday.

spaceweather.com and USA Today imply HF communications will be affected but there's only a small chance the power grid will have problems. 

[raybiker73]

Space.com had a good piece about it yesterday as well.

http://www.space.com/27110-sun-unleashes-big-solar-flare.html

[gil]

Hello,

Last night's sked with Ray on 40m was pretty noisy with lots of QSB (fading).. I did get most of it but was glad for the earphones.. Sorry Ray, I missed tonight, I was talking to a girl at the coffee shop ::)

Gil.

[RadioRay]

I put my cellphone into the microwave oven and set it to cook a 25 pound turkey.  I think it's safe from EMP now, because it no longer rings. 



For that matter, it no longer even looks like a cell phone.

de RadioRay ..._  ._



Ps.  Gil - Good choice!     ;) :-*

[cockpitbob]

I think it's going to be a waste of time, but I'm about to go hike the biggest hill within 30 minutes;  all 195' of it :P .  It's in a wooded, dark area and is bald, so no trees to block my attempt to see the aurora.
Anyone else going to try to catch a glimpse of the aurora?

[RadioRay]

The thought had occurred to me. I live in a rural area, but I am just below the forecast fringe to see it and the horizon due north is DC/Baltimore light pollution.  All those muzzle flashes and burning businesses make it tough to see the aurora ...  ;-)


Let us know how it works for you, please.


>RadioRay ..._  ._

[cockpitbob]

Nuthun.  I had a nice1 mile night hike though.  I'm 25miles north of Boston.  Maybe it will get better before morning, but a full moon is just rising and I don't think the northern lights can compete with that, even on good day.