Posted: Thu Jul 10, 2008 10:36 am Post subject: Crystal sets, anyone?
I've been giving some thought to constructing a crystal set for myself, out of as old-school parts as can be obtained — including a galena crystal and metal "tickler" which I'm pretty sure could survive an EMP burst.
My reasoning is this: in a scenario where there's no juice, it might be helpful to be able to pull in whatever broadcasts are taking place to help gain a sense of what's going on...
Not there there'd necessarily be level-headed, helpful broadcasts at a time like that, but there might be something, and it, whatever it might be, could be helpful in gauging the temperature of things.
AM-FM, good SW receiver, CB walkie talkies, weather radio, and a couple of the new walkie talkies. All pretty cheap, and covers the spectrum of broadcasts. All available to run on 12 volts, too. _________________ Local fix-it guy..
Posted: Fri Jul 11, 2008 9:58 am Post subject: Re: Crystal sets, anyone?
Check out Ebay for radios sold under the brand names "Degen" and "Kaito". They sell small portable radios that cover all of the AM band, shortwave bands and some are general coverage receivers (0.1-30 Megahertz) with SSB capabilities. They can be had in the $30-$70 range depending on capabilities. They'll run for days off 4 AA batteries, which can be charged with a small solar charger. If you're worried about EMP store a kit in an ammo can.
Radio Shack sells a little shortwave radio that's the size of an old fashioned AM portable, fits in your shirt pocket, for about $30. It's not near as good of radio, but it does work in a pinch, and you can pick one up about anywhere.
Posted: Fri Jul 11, 2008 10:14 am Post subject: Re: Crystal sets, anyone?
bobaloo wrote:
Check out Ebay for radios sold under the brand names "Degen" and "Kaito". They sell small portable radios that cover all of the AM band, shortwave bands and some are general coverage receivers (0.1-30 Megahertz) with SSB capabilities. They can be had in the $30-$70 range depending on capabilities.
do you have any model names or numbers to share?
a bud had suggested I get an eton radio that looked in the $200 range..the next up model was $400...I'd like to keep what I pay toward the price range you mention...
I thought about building one myself, just for fun. I built one in 6th grade for a science project and had a blast with it then. the kids in my class were amazed back then in................uh... uh... 1966!
If you're trying to have somehting to build after an EMP blast, dont you think the EMP blast would have fried the transmitter of the signals you would want to listen to?? _________________ "Battle not with monsters, lest ye become a monster, and if you gaze into the
Abyss, the Abyss gazes also into you."
Ammo at a gunfight is like bubblegum in grade school: If you havent brought enough for everyone, you're in trouble
The Degen 1103 is a great radio, I checked and there's a bunch of them for sale on Ebay. General coverage 100KHz - 30MHz with 1KHz digital tuning, plus a "fine tune" and BFO for CW and SSB transmissions. I use mine all the time when camping, it runs for a couple of days off a set of AA batteries, very sensitive and you can plug in an external wire antenna. Also has switchable bandwidth, wide or narrow. 10 years ago it would have been a $1000 radio if you could get it at all, today it's well under $100.
If you're worried about EMP just keep it in an ammo can, or wrap it in the old reliable, aluminum foil. I don't believe EMP would take out a portable radio not connected to the power lines unless the antenna were extended and it was on, unless you were awfully close to the blast. EMP relies on induced currents from power lines or antennas, it doesn't zap everything, some reasonable precautions should offer some protection. I have seen comments that one plan was to use a series of EMP bursts, so that after spares were hooked up they would be taken out by the subsequent burst, guess it depends on if you're worried about attacks by a nation-state or a small group.
I keep my radio gear unplugged and disconnected from the antennas when not in use, that way don't have to worry about "God's EMP" aka lightning. Lightning can have the same effect as EMP, inducing high voltage/current spikes in power lines.
If you're trying to have somehting to build after an EMP blast, dont you think the EMP blast would have fried the transmitter of the signals you would want to listen to??
Any commercial location that has not protected itself from an EMP is not worth the time it takes to listen to their content. Protecting a system is straight forward for an electrical engineer. I myself do not understand the complete details, but I've read enough to know it's possible by anyone who want's to spend a few bucks to figure it out. _________________ When somebody makes a statement you don't understand, don't tell him he's crazy. Ask him what he means. -- Otto Harkaman, Space Viking
This reminds me of my old eagle scout project. We set up network of battery powered transmitters and receivers across 4 local towns and one hilltop so that the Red Cross in each town could communicate w/ each other. Tested the spots to make sure they would work. I would bet my right arm the guy that helped me still has the radios we used. Funny thing, we had them rigged up in 5 gallon buckets. I don't think it'd take much to transfer them to big ammo cans. I have one myself that used to hold mortar rounds. Maybe a 3 gallon capacity. I plan on moving back to that area in December or so, perhaps its time to visit some old connections. Haha, I think my amateur license is still good too.
Joined: Sep 29, 2004 Posts: 2330 Location: Pennsylvania, USA
Posted: Tue Jul 22, 2008 9:40 am Post subject: Re: Crystal sets, anyone?
jlw61 wrote:
Specop_007 wrote:
If you're trying to have somehting to build after an EMP blast, dont you think the EMP blast would have fried the transmitter of the signals you would want to listen to??
Any commercial location that has not protected itself from an EMP is not worth the time it takes to listen to their content. Protecting a system is straight forward for an electrical engineer. I myself do not understand the complete details, but I've read enough to know it's possible by anyone who want's to spend a few bucks to figure it out.
Use military grade (rad hardened) semiconductors to build your radio set. Another alternative; go back to vacuum tubes! Another thing to consider is that unless they are very local; EMP blasts are not 100% effective. If you are really paranoid, you can build a "tin foil hat" around your house or just one room containing all your electronics, aka; Faraday cage. All connections from outside of your cage will need to be "spike" protected in some manor such as a varistor or in the case of shielded cable, lightning arresters (a wire braid from shield to earth ground at point of entry) on the shields. You can buy that stuff at Radio Shack.
You can make your Faraday cage out of tinfoil or window screening, whichever is more convenient. It must be connected to earth ground every several feet and it must cover all walls including the ceiling and floor, unless you are at ground level, on a concrete slab (or dirt) in which case you can leave the floor uncovered. _________________ "That's the problem with mercy, kid... It just ain't professional" - Fast Eddie, The Color of Money
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