Ham Radio Explained, Sort Of
Reports say applications for Amateur Radio (HAM) Licenses have skyrocketed in recent years (I wonder why!) and there’s been a lot of talk of using it for communications in a post Fan Event. I’ve been a Ham operator, off and on, for the past fifty years and a NAVY Radioman for twenty of ‘em. There are so many different areas of interest within the hobby that it would take many books to cover them. There are “nets” where HAMs gather on the same frequency to talk about their favorite subjects or just B.S. late into the night. Some HAMs like to do nothing but make phone patches (*1) for ships at sea; others like to experiment with different antenna configurations or just like to see how much distance (DX) they can achieve. Then, O.M.G., the contests! I know there’ve been divorces (or at least, fights) over the old man (OM) spending whole weekends on the air trying to make the most contest contacts with other stations/countries in a specified time. (Make me a sandwich, I’m busy here!) (*2) I can talk to anywhere in the world IF I have a transmitter of sufficient output power and a good receiver, IF I’ve chosen the correct frequency range for the distance, time of day, year, sunspot cycle, IF my antenna is designed for that frequency range and oriented in the right direction, IF propagation is good, IF natural (static) and man-made interference isn’t too bad, IF someone happens to be listening on the same frequency, and IF the guy on the other end speaks English (*3). I want to try to illustrate that there is a little more to it than the YouTube videos imply. What the video usually doesn’t show is that big honkin’ antenna on a tower out in the back yard (Not exactly low-profile for your BOI.). We can make “stealth” (*4) antennas or vertical antennas of various configuration but they all sacrifice efficiency for size. (And bigger really is better.) Before you go out and pay over a Kilobuck for that Sooper-Dooper Freq-Scooper there are a few things you need to know. 1. Some knowledge of radio wave propagation (*4) at different frequencies (What’s a frequency?) would be helpful. Some newbies seem to get hung up on this “frequency” thing but it’s really pretty simple. “Frequency” is the number of times something happens in a given period of time; She goes to church at a frequency of once per week. “A frequency” is a specific point in the Electromagnetic Frequency Spectrum (*4); “Tune to such-and-such frequency and listen for me there.” (*5) Let me bloviate (*4). If we take a length of insulated wire, coil it around an iron rod and attach each end of the wire to a battery, we’ll have made an electromagnet. The battery current through the wire creates a magnetic field that the coils and rod tend to concentrate. If we reverse the wires on the battery terminals, the field collapses and then builds up again when current flows in the opposite direction. We’ll call this “one cycle” of reversals. If we reverse the wires at a speed of, say, 60 times per second, we will have reached a frequency of 60 reversals, or cycles, per second, or, 60Hz (Hertz) (sound familiar?) Now, let’s lay that wire out straight, attach one end to one battery terminal and connect the other battery terminal to an earth ground (*4). The instant the battery is connected the magnetic field around the wire builds and then collapses because the other end of the wire is not connected. When we reverse the battery terminals, the same thing happens. As we increase the frequency of reversals, reversing them faster and faster, we reach a point where there isn’t enough time for the magnetic field to fully collapse before the next cycle begins. This is the beginning, or lower end, of the Radio Frequency (RF) portion of the EM Spectrum(*6); the point at which the expanding and collapsing magnetic field around the wire, acting against the earth ground sends electromagnetic waves radiating away from the wire in all directions, like a stone dropped in a still pool of water. (Voila!) On the receiving end, the electromagnetic waves crossing the wire of a similar antenna cause a small voltage to be generated and sensed by the receiver. OK, we’re hummin’ along, reversing these wires at, oh, one million times, or cycles, per second; we are radiating a continuous wave (CW) at a frequency of one Mega-Hertz (1MHz) that can be detected by a receiver tuned to the same frequency. Only, there’s no information, no intelligence on this signal; it’s just a steady tone in the receiver. There are many ways to place information on it; the simplest being to interrupt it using some sort of coding the guy on the other end understands (Morse Code). We can modulate (*4) the signal by varying the transmitter output strength, (amplitude modulation or AM); we can vary the base frequency up or down a few KHz (frequency modulation or FM) and in many more ways that go beyond the scope of this article. (In other words, I know what they are but can’t explain ‘em easily.) 2. Some knowledge of matching your antenna to the transmitter at the frequency you’re operating on would also be nice. (Transmitters can be destroyed by a mismatch.). Antennas come in all shapes and sizes and almost NONE of them are the correct length for the frequency you’re trying to use. Basically, an antenna coupler electrically fools the transmitter into thinking the antenna length is correct; they are simple and generally inexpensive. 3. A lightning arrestor between your antenna and coupler helps you sleep better at night. 4. The license classes are in ascending order of the amount of technical knowledge you need to pass the exam and speeds at which you used to have to be able to send and receive Morse code (no longer required but impresses the heck out of visitors to your shack (*7)). The Technician Class License replaced the discontinued Novice Class as the entry-level class of license. It pretty much allows someone to get their feet wet in the hobby without spending a ton of money to get on the air and see if they want to go further. They’re somewhat limited in operating frequencies and transmitter output power. Equipment that operates in the Very High Frequency and Ultra High Frequency (VHF/UHF) sections of the RF portion of the EM Spectrum (*4) are pretty much plug-and-play and only line-of-sight. Sometimes they’ll reach over the horizon, but not reliably. Many ham clubs sponsor a repeater (*8) located on a tall building or mountain top for wider coverage that may provide local telephone access, be networked with other repeaters across several States or even provide internet access by interfacing your computer to your radio. Usually the club requires you to become a member to help defray maintenance costs through dues. If this is all you might be interested in, then the Technician License is all you need. If you really want to reach out and touch someone or listen to someone on the other side of the globe, you’re going to have to use the Ham Bands (*9) in the High Frequency (HF, A.K.A. Shortwave) section of the RF portion of the EM Spectrum (Ya keepin’ up with this?). The General, and Extra classes have the most frequencies and the highest output power allocated here. (The Extra class is generally the over-achievers who really get in to this electronic stuff.) So, what is it I’m trying to say here? If you think you’re going to use a HAM radio to replace your cell-phone, you’re going to be Way disappointed. It’s really not a viable solution for the average Prepper starting from zero. If you just want to find out what’s going on around the country all you need is a length of wire dropped out a window or tossed over a tree, (*10) AWAY FROM POWER LINES, a grounded “general coverage” or “all band receiver” and a little of the above-mentioned knowledge. Using just a seven foot steel rod out in the yard and knowing what frequencies to listen on, I routinely hear stations all over the world and in the U.S.; HAMs talking about the heat in the East, gas prices in the Pacific Northwest, drought and crop problems in the Midwest and any number of other things you won’t hear on the News. That, by itself, would alleviate the sense of isolation you would have in a SHTF situation. AND…you don’t need a license. If you feel you must be able to transmit, then, as much as I hate to say it, a Citizen’s Band (CB) radio with a good antenna would be a better alternative in the short term. They’re inexpensive and simple to hook up and operate (A.K.A. Sailor-proof) and if enough people had them and used a little operator courtesy, they’d create a network covering an enormous area. HAM Radio is a great hobby but it takes time to learn and gain the on-air experience you need to communicate the way you want (and some would tell us time is at a premium). As far as what to get, I highly recommend you contact a HAM or HAM club in your area (phone book). They’ll be more than happy to talk your ear off with recommendations (see: bloviate, above). NOTES (*1) phone patch: communicate over a long distance with an operator who then connects you to his phone line to make a local call. It allowed me to talk with my family from overseas when a parent died and it allowed me to let them know I was OK after a major accident on my ship in the Western Pacific. The best phone patch I ever ran was at sea off the East Coast. A young crewmember’s wife was overdue with their first child and he was going nuts. I found a station in the Midwest to run the patch and the first thing we heard was his wife asking “Are you glad it’s a girl?” The poor kid was speechless; I had to chit-chat with his wife until he got it under control. (*2) My personal interest is low-power CW (a dying art) to see how far I can get with the least amount of transmitter power. (*3) Not so much on that last one; HAMs use generic “Q-signals” (*4) to exchange basic information, but you get the idea. (*4) Google it, Bing it; whatever search engine you use. (*5) HAMs never, ever use the term “channel”, unless they want to sound like a CBer (a lower life-form). (*6) you really should have Googled this by now. (*7) As in radio shack: 1) literally a structure added to early merchant ships as an afterthought to house that new-fangled wireless thing, usually placed somewhere high on the superstructure to facilitate access to the wire antennas strung between masts or 2) a shed or addition to the garage out in the back yard because the wife (XYL) wasn’t going to have all that junk in her living room, an early form of man-cave that also facilitates access to antennas. (*8) Repeater: Unit that receives your transmission on one frequency and re-transmits it on another frequency at the same time. (*9)The RF portion of the EM Spectrum is divided, by International Agreement, into various “bands” of frequencies allocated for specific purposes; the HAM bands, Commercial Broadcast bands, military, aircraft, Etc. (*10) I’ve had excellent results from a long length of wire and a box kite trailed behind a ship in the Pacific; good Sea-story there. Terms needing more explanation: 1. HAM: I have no idea where that originated, nor do I know why it’s often in capital letters. 2. YL: young lady, usually single; XYL: self explanatory. For those of you who already know this stuff, I’ve used a little Poetic License to try to make some of the theory easier to understand. If you feel I’ve grossly misstated something, I welcome your comments. (Nitpickers will be ignored.) Join thousands of preppers and get all my survival tips for FREE! Subscribe to The Survivalist Blog dot Net via RSS or via e-mail. November 9, 2012 M.D. Creekmore [send him mail] is a full-time blogger and preparedness consultant. He currently lives completely off-grid somewhere in the Appalachian mountains and is the author of 31 Days to Survival and The Dirt Cheap Survival Retreat both published by Paladin Press. To connect with M.D. Creekmore please visit his Survival Blog. Copyright © 2012 The Survivalist Blog
|
