Post by woodyz on Aug 7, 2013 16:47:35 GMT -7
We have had quite a bit of posting on Ham radio operation and several members have acquired the ability and license. I felt like this compulation covers the basic understanding of the process and how it works for those still considering the possibilities.
Primer for Ham radio part one
by Guest Blogger on October 16, 2012 • 8 comments
This guest post is by Michael C and entry in our non-fiction writing contest .
(This is part one of a four-part series - intro, history, AM, Carrier)
There are less than 4 million active ham radio operators in the USA – about 1% of the population. I use my ham radio mainly to contact a friend about ten miles away. I don’t get involved with the contests or DXpeditions - just wanted a better radio then the CB radio. Ham radio is about contact between two people at a distance – sometimes great distance like around the world. I am going to try to explain Ham radio above the “refer to a book” level for those considering ham radio as a means of communication. A slight history of Radio is in order to bring those who don’t know much about “radio” up to speed.
A man by the name of Hertz discovered electromagnetic waves could move through the air and effect a similar shaped “receiver”. The first real radio was made by someone named Marconi. Radio was born but not before a man by the name of Tesla figured out that tuning different frequencies were possible. Amateur radio operators were some of the first people to take advantage of the “wide open airwaves” with the first radios built.
The radios were cheap to create – a crystal set only required finding a good crystal, a coil of wire and an earphone. The Edison light lead the way for the radio tube which allowed the “amplification” of any signal. The incoming signal from the antenna is amplified and then the audio signal is amplified. A small tube receiver can amplify signals hundreds of times – allowing weak/far away radio to be heard. So, for a few bucks more you could have a pretty good radio that played through a speaker. The transistor was capable of amplifying the signal thousands of times and saving some battery power.
Even though Morse code is the easiest signal to transmit, it is not vocal and I will confine my article to verbal transmission. Audio signals are the “real time” type of communication needing constant update. AM, SSB & FM transmission modes were developed for audio. It would be criminal to not mention ARRL (Amateur Radio Relay League) an organization that has supported ham radio operators almost since the beginning. For those who have never operated a radio – just press the key on the microphone and talk, then release the key and listen for a response.
AM
The first and easiest radio mode is the AM (Amplitude Modulation) radio. CB radio is AM radio transmission based. The concept is simple – put a sound wave inside (or outside) of a “carrier” wave. The sound wave is audio frequency, for the early microphones about 300 to 2000 Hertz. The carrier wave is a mirrored sine wave that cycles at the “air wave” frequency. The sound wave is simply “fitted” into a carrier wave shape.
Although the sound wave “edges” the carrier, if there were no sound – the carrier would still be created and transmitted. This was called an empty carrier or in CB slang a “dead key”. This is used to “drown” out other CB’ers. I mention mirrored sine wave – the “electromagnetic” field created (by the antenna) has a north pole and a south pole. Both of these poles (amplified signal) must be beamed out by the antenna. The frequency of “AM Radio” is around 525 to 1710 (1.71 MHz) Kilo cycles and if we care about ham radio frequencies then the first ham frequency begins at 2 MHz (2000 Kilo cycles) and extends to 4 MHz. AM dominates the HF (High Frequency) spectrum up to about 29.0 MHz where FM is finally available. It is the age-old problem for FM – not enough band width to support the mode.
Primer for Ham radio part two
by Guest Blogger on October 17, 2012 • 10 comments
This guest post is by Michael C and entry in our non-fiction writing contest .
Single Side Band (SSB) transmission is available on higher end CB radios and of course, in ham radios that support the mode. Think of the “mirrored sine wave” cut in half. That half of the signal uses less than half as much power. Also, lets get rid of the carrier so that if there is no sound, even though you are keyed up, there is no signal. All CB radios transmit at 4 Watts of power (per FCC regulation) but on side band that amounts to 12 Watts since the “average” of the sine wave (for a half height signal) is used. Radios that have SSB have a choice of USB or LSB (Upper/Lower Side Band) which does allow for double the number of channels for CB’s. Ham radios don’t have near as much of a channel crunch with thousands of options.
SSB is really a “person to person” mode because both operators must “fine tune” their radio to each other. It goes something like this; first radio operator gives a count of ten and the second operator twists the fine tune knob until the first operator does not sound like a chip monk and not like “Jabba the hut” either. The second operator then gives a count of ten while the first operator tunes in. A third operator cannot participate since he can only tune in to one or the other operator, then the other operator sounds like a chip monk or “Jabba the hut”. The third operator also sounds odd to BOTH of the first operators since neither is tuned in to him/her.
FM
The circuits that made radios better, more reliable, also allowed higher frequencies to be used. Electronics allowed the signals to be manipulated in ways not done before. The FM (Frequency Modulation) transmission mode varies the “frequency” of the wave with change in sound.
I’ll use FM stereo radio (88-108 MHz) as an example. It works like this – start with a base line frequency like 100.1 FM then add the audio count (20-20,000 Hertz) to the base (100.1+20,000=100.12) to get a transmit frequency.
The right channel (radios are south paws) of the stereo signal is subtracted from the base and transmitted separately. There is no stereo mode for ham radio. FM broadcasts have very high fidelity compared to AM broadcasts. Lightning does not make FM crackle like it does AM. This is because lightning cannot affect the frequency, only the amplitude or power.
An early problem was FM drift in which the FM signal “drifted” out of frequency – PLL (Phase Locked Loop) circuits corrected this. In fact most ham radios have digital tuning. FM transmission is the dominant method for frequencies above 29 MHz. You’ll also notice something nice about the FM signal – it’s constant strength. The power (amplitude) does not change like AM does. AM transmissions are low frequency which means big waves and big antennas.
The big waves can travel a long distance as “ground waves”. The AM waves can “circle the globe” by reflection off the ionosphere which occurs mainly at night. Sky wave bouncing is an interesting subject in itself but since most people are going to start as a tech – all of the bands that you will be allowed on are “line of sight” bands. You would have to become a General (ham license) to operate on HF bands then you would already know about bouncing your signal.
Primer for Ham radio part three
by M.D. Creekmore on October 18, 2012 • 12 comments
This guest post is by Michael C and entry in our non-fiction writing contest .
Frequencies
Since the start of radio, frequencies have been allocated for different purposes. There are over 10 thousand different frequencies for ham radio, starting with HF (high Frequency) and going into VHF (Very High Freq.) and UHF (Ultra High Frequency). Even higher bands in the gigi-Hertz range are open for use by ham operators.
The most common band is 2 meter (144-148 MHz), it is recognized around the world as a common band and radios can be bought for less than $100 (USD). The second most common band is 440 (70 cm) band, a little smaller then 1 meter. It is also common around the world. If you hear of “dual band” the radios will most likely have 2 meter/440 band reception. I should note here the difference of dual band and dual receive.
Dual receivers pick up 2 signals at once (you will have 2 volume controls) and you can transmit on either band, you can only listen to one band, at a time, on a dual band radio. Between just those 2 bands you have over 500 frequencies to transmit on – enough to give you frequency anxiety. Compare that to the 40 channel CB and you have a major incentive to “move up” to ham radio.
At one time the FCC was petitioned to open the 11 meter (CB band) to a hundred channels or more (not including the current 27) but figured that would wipe out ham radio – not very many people are trying get a ham license as it is now. That problem is mitigated (slightly) now by eliminating the Morse code requirement for a ham license.
The other problem is that people have to be responsible for their actions – you will have a call sign and declare it every time you connect with someone. Other ham operators will not tolerate CB’er like talk (or antics) and their calls to the FCC get action.
The FCC takes equipment away from power running CB’ers - they jail someone bothering ham radio operators. Also remember that you represent America – having a general license allows you to “call the world” on your radio – the FCC will be listening (and other ham’ers) so talk nice.
There are levels of class of ham radio operator, right now Technician, General, advanced and Extra. Most people start at Technician but passing the general, advanced and extra tests at the same sitting would get you an Extra license right out the door at day one.
The main difference between the ham classes are the frequencies that you are allowed to transmit. Anyone can buy a ham radio (or scanner) and listen to any frequency, even military or police frequencies. Transmission however is a different matter – you are only allowed to transmit on the frequencies that you are certified.
If military or police are transmitting (during a disaster they may “borrow” civilian equipment) on ham frequencies – they have the “right of way” and you have to find another frequency. Although, if you want to get help, using ham radio will give you an edge over other “needies” since you can talk to the aforementioned folks.
Tech – privileges start at 6 meter and go up to 1.24 gigahertz. There are frequencies above 1.24 GHz available but there are so few operators using or radios made that I won’t bother you with them. I won’t bore you with all the frequency numbers as I provided a chart (old) with a graphic view of each band including numbers. I will point out that there are different uses – even within each band – specified for ham operators. For instance, the 2 meter band has SSB (“no FM”) set aside on some frequencies.
Now, all those counting the 2 meter freq. count are going to say, “there is only about a hundred frequencies available for FM voice”, and I say (FCC agrees) if a frequency is not being used – it is available for use. Very few people are using digital modes so you could use one of those frequencies to talk to someone. Although, there are enough frequencies to go around for the few ham radio operators out there.
General – get all the bands that are available to Tech operators (VHF/UHF) and a lot of HF bands too. In fact going from Tech to General gets you the most bands of any class upgrade. The HF bands can be a door to the world. There are HF only rigs that cost hundreds just for talking to someone in another country. Consider yourself a true ham radio operator if you get your General license.
Advanced – gives you a “few” more HF band spots with the license. If you wanted to talk to your friend (in another state or country) and you both had advanced privileges you could find an almost never used frequency. There are a lot of advanced operators out there, when the code requirement was cut many Generals took Advanced tests and passed. At this class you can transmit on 95% of the ham spectrum.
Extra – anyone having an Extra license is an over achiever. This class is the end of the line, top of the heap, all bands open license. Of course, if you think that Extra’s are hanging around the 5% of the airwaves – they are talking to our neighbors around the globe on every band.
Primer for Ham radio part four
by Guest Blogger on October 19, 2012 • 19 comments
Gear.
This guest post is by Michael C and entry in our non-fiction writing contest .
Ham radio operators have the unique ability to build their own radio. No other class of radio operator (commercial broadcaster, military operator) is able to do that. You could put together a bunch of recycled/junk parts and “talk” out of it – without FCC part 15 certification. Most ham operators buy their radios since the commercial offering has become so advanced. Modern DSP chips make HF radio more pleasant to listen to, digital tuning, preset bands, lots of buttons and back-lit dials. The big rigs that have more than 30 buttons can go for $10,000 (yes, Ten Thousand USD) and are aimed at the over achieving Extra who wants to win DX contests and soon to be divorced.
Ham radio operators have the ability to run their equipment at any power level. A CB radio can only transmit at 4 Watts of power, ham operators can run 2000 Watts if need be. Although ham operators are supposed to use only what they need to communicate effectively. Ham radios normally have 5, 10 and 50 Watt settings, the big “all band” radios have “dial a Watt” knobs to specify how much in single Watt increments but the top is about 100W. Need more power – buy a linear amplifier for lots of money, of course.
Ham radio operators have the ability to transmit in various modes. Did you learn Morse code as a young scout or have a computer? Not only can you transmit in Morse code but there are computer modes (PSK) as well. You are not limited to AM or FM (which includes SSB and narrow band FM) voice modes because there is also digital voice encoding. For TV watchers there is SSTV (Slow Scan TV) mode.
Ham radio operators have the ability to run remote (remotely operated) radio equipment. You may have heard of ham operators talking through “repeaters”. This is a dual band radio that takes a signal and re-transmits it on another frequency. The high frequency signal is just above the low frequency signal but far enough so there is no “cross talk”. The repeater can receive and transmit on both frequencies but not at the same time. Ham radios can usually catch the whole conversation because they have pre-programmed band usage. The ham radio knows the frequency it is on is a repeater only frequency. Repeaters are used mostly to contact other ham operators from farther away. I mentioned that all VHF/UHF bands travel in a straight line – that means if your behind a hill you can’t hear anyone. If it is your hill you could put your own private repeater on top and hear everyone. Most repeaters are put up by ham clubs which share the cost but allow all hams to use. Special goodies like radio to phone line hookup (making a phone call through your ham radio) are reserved for club members. It’s not too hard to join a club – you are already a ham operator, donations may be accepted. If you use a certain repeater a lot you may want to support them.
Ham radio operators have the ability to build their own antenna. This is also unique to ham operators. This is something that you really could do (unlike building a fancy radio) with some copper wire or an old box-spring. A whole book could be written about this (oh yeah ARRL did) subject but I will cover one aspect. There are “directional” antennas that will beam your signal in one direction. You can limit your broadcasts so that you are not heard in other directions.
Last thoughts
After you get your license – you are going to want to get a radio. Your choices here are so unlimited that I just have to say, “keep your original objective in mind”. Did you want to talk to your prepping friends or talk to the folks in Denmark? Both ends are achievable with an all mode/all band radio. Talking to your friends on 2 meter in AM (SSB) would restrict reception to only radios that can listen to AM-SSB signals on 2 meter. Talking to Denmark requires HF bands (and a General license) and AM mode. Be careful not to start “band collecting” just because you can transmit (legally) on that band. Then comes the “gotta sell some of these radios to get the radio that I really want” day. The smallest ham radio is a hand held or handy-talky some of which are smaller then a pack of cigarettes, the largest radio will make you feel like the captain of a star ship (what’s this “satellite” button).
For greatest OP-SEC try for a little used band, 1.2 GHz is little used because the radios are 700 to 1000 (USD) new. The UHF bands 222 and 900 MHz are little used because they are not internationally recognized and the 900 MHz is torn by garage door openers, walky-talkies, old cordless phones, etc. Use a computer program (PSK) to have the shortest transmission time possible. Use the AM mode if available – FM band scanners do not recognize AM signals. Use the least power for transmission – works good with solar power. Use a directional antenna, you can also reduce the power some more.
HAM RADIO EXPLAINED – sort of
by Guest Blogger on October 30, 2012 • 21 comments
This guest post is by Dave L and entry in our non-fiction writing contest .
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.)
Getting started in Ham Radio
by Guest Blogger on October 4, 2012 • 73 comments
This guest post is by Raybiker73 and entry in our non-fiction writing contest .
Not long ago, I read an excellent guest post on this site by Tom C titled “Understanding the Fundamentals of Radio Communication: Is Anybody Out There?” Tom pointed out the importance of understanding radio fundamentals, and provided some great starting points for anyone who wishes to obtain their amateur radio license.
As a recently-licensed ham, I understand how intimidating the idea of testing can be. I wanted to obtain a license for many years, but the test just seemed to be a bit too daunting. This past spring, I decided to finally jump in and give it a try… and I did it! Not only was I able to pass the entry-level Technician Class test, but I passed the mid-level General Class test as well. It took a bit of study, and it wasn’t easy, but it wasn’t impossible, either.
The other thing that I found intimidating was the Morse code requirement. Previously, each license level required an increasingly hard Morse code test in addition to the standard multiple choice test. However, the Morse code requirement is no longer part of the testing, which means getting your license is easier than ever before.
The hard part began after I passed the test. What radio should I get? Handheld or base station or portable? Should I build a dipole antenna or a beam antenna? Where do I get all this stuff, how do I put it together, and how do I get started actually USING it?
I’m sure I’m not the only one out there with questions, but I’m learning, and I’d like to share my experiences with those of you who want to learn as well. It’s not something we can complete overnight, but if we work together, I think we can figure it out. I’ll start with the first step in the process: preparing for the Technician-Class examination.
There are three levels of amateur radio license: Technician, General and Extra Class. The primary practical difference between the various license classes is access to frequencies. The FCC has established a series of amateur radio “bands,” or blocks of radio frequency to which amateurs have access. Technicians have limited access to some of these bands, Generals a bit more access, and Extras have full access to all bands.
So, you’ve decided that it’s worth a try, and you want to prepare for the Technician-class exam. The question is, where do we get started?
There are two books you will want to get before you do anything else. The first is the ARRL Handbook for Radio Communications (as mentioned in the previous article by Tom C). This is a book that will be on your shelf for many years to come, as it contains reference material and information useful to ham operators of every class. Think of it as your “Ham Bible” – if you’re looking for answers or inspiration, you’ll find it in here. This book is available from the ARRL at www.arrl.org.
The second book you will need is “Technician Class 2010-2014,” by Gordon West. West’s book provides the entire question pool for the Technician Class exam, all 394 of them (Don’t panic! Only 35 questions will be on the actual exam). Rather than just providing a list of questions and multiple-choice answers, West’s book organizes the pool into blocks of related questions, and provides the background information for each question. This book is invaluable in exam preparation in that it not only provides the entire question pool, but helps you to understand the rationale behind the answers. Where the ARRL book can be considered your Ham Bible, consider this book to be your Technician Class Textbook. You can find West’s book at Amazon or other retailers.
Finally, you’ll want to take some practice tests – nobody wants to go in cold, right? There are a couple ways to do this. Many sites offer online practice exams, but the best that I’ve found was the AA9PW site at aa9pw.com/radio/. There is a link on the main page there that will generate a practice test for any of the three exam classes, using questions randomized from the question pool. A practice test only takes about 5 or ten minutes, and I found that doing this a couple times a day when I had a moment to spare was a great help when it came time to take the real thing.
Practice test apps are also available for portable devices. The one that I found most useful was Amateur Radio Exam Prep: Technician, by Patrick J. Maloney LLC. This is available for iOS devices such as iPhone and iPad, and is available in the iTunes store. Exam apps exist for other platforms such as Android, but as I haven’t used them I don’t feel qualified to recommend any specific one. A simple online search will show a lot of apps for whatever platform you prefer.
With these three items in your arsenal – the ARRL book, the West book and a means of taking practice exams – you’re ready to take on the Technician Class exam! Again, it’s challenging but not impossible. If you study the materials a bit and take the practice exams, you’ll have no trouble at all.
Like most of you, I’m just starting on my ham radio adventure myself. In future articles, assuming the interest is there to support it, I’d like to go over the nuts-and-bolts of taking the exam, the basic electronic theories and components you’ll need to know, and preparing to upgrade your license if you so choose. I’d also like to take you all along as I jump into ham radio: choosing a radio, choosing and constructing antennas, and actually getting on the air to talk to people. I hope you’ll join me, and I hope to hear you all on the airwaves!
(disclaimer: any books or materials I recommend are ones that I’ve used. I don’t receive any compensation, nor am I in any way affiliated with any of the producers or publishers. I’m only stating what’s worked for me personally. Thanks!)
Getting started in Ham Radio, part 2 – wavelengths and watts and whatnot
by M.D. Creekmore on November 21, 2012 • 7 comments
This guest post is by Raybiker73 and entry in our non-fiction writing contest .
You can also read part one here.
So you’ve already decided on getting an amateur radio license, and you find yourself with a few questions. One of the first questions you have is probably, “What is all this ‘wavelength’ and ‘meter band’ and ‘HF’ stuff?” Or, maybe you wonder what that guy was talking about when he invited you to “check in to our prepper net down on 80, we’re at 3850.” Like most pursuits, ham radio uses some specialized jargon. Let’s try to clear up a few of the basics.
“What is all this crap?”
SURFING THE WAVELENGTHS
Ham radio operates on certain segments of radio frequencies, or bands. Just like AM radio is found between 540 and 1710 kHz, and FM radio is found between 87 and 108 MHz, ham radio has its own sections of bandwidth to occupy. These bands are generally referred to using the approximate physical wavelength of the radio waves. For instance, the “80-meter band” runs from 3.500 MHz to 4.000 MHz (3500 to 4000 kHz), as 80 meters is the approximate physical wavelength of a radio wave at those frequencies. Likewise, anything from 28.000 MHz to 29.700 MHz is considered the “10-meter band,” and so on. Remember, these are approximations, as wavelengths change with every change in frequency. The “band plan” designations just make it easier to group them together.
If you know the frequency and want to calculate the approximate wavelength, there’s an easy formula to get a fast-and-dirty result. Just take 300 divided by the frequency in MHz. For example, using this formula with 146.5 MHz, we come up with a result of 300/146.5 = 2.047. Correspondingly, 146.5 MHz is found in the 2-meter band. Another one, 14.150 MHz, would be 300/14.150 = 21.20. That means that 14.150 falls in the 20-meter band.
Frequencies in ham radio are referred to in either megahertz (MHz) or kilohertz (kHz). 1000 kHz = 1 MHz. You might hear somebody referring to a contact they made on 40 meters at either “seven point two” or at “seventy-two hundred.” That’s just two ways of saying the same thing. 7.2 MHz = 7200 kHz. Using our previous formula, 300/7.2 = 41.66, so that frequency is in the 40 meter band.
So, when that guy earlier asked you to join a discussion net “down on 80 at 3850,” you now know that if you tune in to 3.850 MHz on the 80-meter band, that’s where you’ll find him. Pretty easy!
“Basic list of frequencies”
WHAT’S THE FREQUENCY, KENNETH?
For those of you who are old enough, do you remember your old TV set that had separate dials for VHF and UHF? Those terms stand for Very High Frequency and Ultra High Frequency, and while your TV shows now come via cable or satellite, VHF and UHF, along with HF (High Frequency), are still terms you encounter every day in ham radio.
Although there are frequencies both above and below, the three most common in ham radio are HF, VHF and UHF. Ham radio HF starts at 1.8 MHz (just above AM broadcast frequencies) and goes the whole way up to 30 MHz, and includes the 160-, 80-, 60-, 40-, 30-, 20-, 17-, 15-, 12- and 10-meter bands. This is the frequency range that you’ll sometimes hear referred to as “shortwave.” Ham radio VHF starts at 50 MHz and goes up through 300 MHz, and includes the 6-, 2- and 1.25-meter bands. FM broadcast radio (87 MHz-108 MHz) falls in the middle of this segment. Ham radio UHF frequencies start at 300 MHz and run the whole way up to 3000 MHz, and you’ll find most users on the 70-cm and 33-cm bands. Great, so… what’s the difference?
The short answer to that question is “distance.” The HF bands are generally more geared towards long-distance communication, while the VHF and UHF bands are for more local communication. For example, in an SHTF situation, most of your communication with the outside world would be on the HF frequencies, and for local operations the hams in your group would likely be using handheld or mobile VHF radios to communicate with each other. Those rules aren’t written in stone – you can talk to someone just a few miles away on HF, and if conditions are right you can get out pretty far on VHF, but generally, lower frequencies = longer potential communication distance. For a person holding a technician license, most of your operating will be on VHF and UHF, where you have full privileges. Technicians have some very limited voice privileges on 10-meter HF, but other than that, if you’re a Technician who wants to use HF, you’re mostly limited to morse code. But, if you have your Tech license and you’ve read this far, you’re probably already chomping at the bit to upgrade to General and then Extra Class, which will open up the whole world of HF frequencies for you!
“Electronics formulas you need to know”
POWER TO THE PEOPLE!
One of the hardest thing for an aspiring ham to learn, particularly one without any electronics experience, is Ohm’s Law. While it might make your eyes glaze over just like high school algebra, it’s actually a very simple formula that you’ll need to understand whenever you’re building or troubleshooting something. It’s also required reading for taking your amateur radio test! There are many formulas that are part of Ohm’s Law, but these are the basics you’ll need to know to get started.
Any beginner’s electronics text will tell you that volts are electric potential, amperes are current, ohms are resistance and watts are power, but what does that really mean? As a kid, I was taught to think of it like plumbing: Volts are the water in the pipe, amperes are the water flow, ohms are the size of the pipe and watts are how much water you get out of the spigot. Lots of water, high flow rate and a large pipe will give you a lot of water in your bucket, while less water, low flow and a small pipe will give you a lot less.
Electricity works in much the same way (just don’t mix the two together!). Put more volts or current in the wire (more water or higher flow in the pipe), and you’ll get more out of the other end. Higher resistance (a smaller pipe) will let through less power than lower resistance. The chart above shows the easy way to calculate these figures.
For example, let’s say you have a 12 volt power source, and you want to generate 2 amps of power. How much resistance will you need in your circuit? As the chart shows, resistance = volts / amps. 12 / 2 = 6, so you’ll need 6 ohms of resistance in your circuit. So, you’ve got your 12 volts at 2 amps, but how many watts of power is that giving you. Power = volts x amps, so 12 volts x 2 amps = 24 watts. Easy! These two basic charts will get you started with most of what you need to know in your ham radio projects.
If you haven’t gotten your Technician license yet, now’s the time to get started. If you have, well, now’s the time to upgrade to General and then to Extra Class! The same resources available for Technician study are also available for General and Extra, so with a little bit of effort, you’ll have no problem at all. In my first entry we talked about licensing, and this time we went over some basics, so next time, let’s start getting some equipment together and then we can get radio active!
www.thesurvivalistblog.net/primer-for-ham-radio-part-one/
Primer for Ham radio part one
by Guest Blogger on October 16, 2012 • 8 comments
This guest post is by Michael C and entry in our non-fiction writing contest .
(This is part one of a four-part series - intro, history, AM, Carrier)
There are less than 4 million active ham radio operators in the USA – about 1% of the population. I use my ham radio mainly to contact a friend about ten miles away. I don’t get involved with the contests or DXpeditions - just wanted a better radio then the CB radio. Ham radio is about contact between two people at a distance – sometimes great distance like around the world. I am going to try to explain Ham radio above the “refer to a book” level for those considering ham radio as a means of communication. A slight history of Radio is in order to bring those who don’t know much about “radio” up to speed.
A man by the name of Hertz discovered electromagnetic waves could move through the air and effect a similar shaped “receiver”. The first real radio was made by someone named Marconi. Radio was born but not before a man by the name of Tesla figured out that tuning different frequencies were possible. Amateur radio operators were some of the first people to take advantage of the “wide open airwaves” with the first radios built.
The radios were cheap to create – a crystal set only required finding a good crystal, a coil of wire and an earphone. The Edison light lead the way for the radio tube which allowed the “amplification” of any signal. The incoming signal from the antenna is amplified and then the audio signal is amplified. A small tube receiver can amplify signals hundreds of times – allowing weak/far away radio to be heard. So, for a few bucks more you could have a pretty good radio that played through a speaker. The transistor was capable of amplifying the signal thousands of times and saving some battery power.
Even though Morse code is the easiest signal to transmit, it is not vocal and I will confine my article to verbal transmission. Audio signals are the “real time” type of communication needing constant update. AM, SSB & FM transmission modes were developed for audio. It would be criminal to not mention ARRL (Amateur Radio Relay League) an organization that has supported ham radio operators almost since the beginning. For those who have never operated a radio – just press the key on the microphone and talk, then release the key and listen for a response.
AM
The first and easiest radio mode is the AM (Amplitude Modulation) radio. CB radio is AM radio transmission based. The concept is simple – put a sound wave inside (or outside) of a “carrier” wave. The sound wave is audio frequency, for the early microphones about 300 to 2000 Hertz. The carrier wave is a mirrored sine wave that cycles at the “air wave” frequency. The sound wave is simply “fitted” into a carrier wave shape.
Although the sound wave “edges” the carrier, if there were no sound – the carrier would still be created and transmitted. This was called an empty carrier or in CB slang a “dead key”. This is used to “drown” out other CB’ers. I mention mirrored sine wave – the “electromagnetic” field created (by the antenna) has a north pole and a south pole. Both of these poles (amplified signal) must be beamed out by the antenna. The frequency of “AM Radio” is around 525 to 1710 (1.71 MHz) Kilo cycles and if we care about ham radio frequencies then the first ham frequency begins at 2 MHz (2000 Kilo cycles) and extends to 4 MHz. AM dominates the HF (High Frequency) spectrum up to about 29.0 MHz where FM is finally available. It is the age-old problem for FM – not enough band width to support the mode.
Primer for Ham radio part two
by Guest Blogger on October 17, 2012 • 10 comments
This guest post is by Michael C and entry in our non-fiction writing contest .
Single Side Band (SSB) transmission is available on higher end CB radios and of course, in ham radios that support the mode. Think of the “mirrored sine wave” cut in half. That half of the signal uses less than half as much power. Also, lets get rid of the carrier so that if there is no sound, even though you are keyed up, there is no signal. All CB radios transmit at 4 Watts of power (per FCC regulation) but on side band that amounts to 12 Watts since the “average” of the sine wave (for a half height signal) is used. Radios that have SSB have a choice of USB or LSB (Upper/Lower Side Band) which does allow for double the number of channels for CB’s. Ham radios don’t have near as much of a channel crunch with thousands of options.
SSB is really a “person to person” mode because both operators must “fine tune” their radio to each other. It goes something like this; first radio operator gives a count of ten and the second operator twists the fine tune knob until the first operator does not sound like a chip monk and not like “Jabba the hut” either. The second operator then gives a count of ten while the first operator tunes in. A third operator cannot participate since he can only tune in to one or the other operator, then the other operator sounds like a chip monk or “Jabba the hut”. The third operator also sounds odd to BOTH of the first operators since neither is tuned in to him/her.
FM
The circuits that made radios better, more reliable, also allowed higher frequencies to be used. Electronics allowed the signals to be manipulated in ways not done before. The FM (Frequency Modulation) transmission mode varies the “frequency” of the wave with change in sound.
I’ll use FM stereo radio (88-108 MHz) as an example. It works like this – start with a base line frequency like 100.1 FM then add the audio count (20-20,000 Hertz) to the base (100.1+20,000=100.12) to get a transmit frequency.
The right channel (radios are south paws) of the stereo signal is subtracted from the base and transmitted separately. There is no stereo mode for ham radio. FM broadcasts have very high fidelity compared to AM broadcasts. Lightning does not make FM crackle like it does AM. This is because lightning cannot affect the frequency, only the amplitude or power.
An early problem was FM drift in which the FM signal “drifted” out of frequency – PLL (Phase Locked Loop) circuits corrected this. In fact most ham radios have digital tuning. FM transmission is the dominant method for frequencies above 29 MHz. You’ll also notice something nice about the FM signal – it’s constant strength. The power (amplitude) does not change like AM does. AM transmissions are low frequency which means big waves and big antennas.
The big waves can travel a long distance as “ground waves”. The AM waves can “circle the globe” by reflection off the ionosphere which occurs mainly at night. Sky wave bouncing is an interesting subject in itself but since most people are going to start as a tech – all of the bands that you will be allowed on are “line of sight” bands. You would have to become a General (ham license) to operate on HF bands then you would already know about bouncing your signal.
Primer for Ham radio part three
by M.D. Creekmore on October 18, 2012 • 12 comments
This guest post is by Michael C and entry in our non-fiction writing contest .
Frequencies
Since the start of radio, frequencies have been allocated for different purposes. There are over 10 thousand different frequencies for ham radio, starting with HF (high Frequency) and going into VHF (Very High Freq.) and UHF (Ultra High Frequency). Even higher bands in the gigi-Hertz range are open for use by ham operators.
The most common band is 2 meter (144-148 MHz), it is recognized around the world as a common band and radios can be bought for less than $100 (USD). The second most common band is 440 (70 cm) band, a little smaller then 1 meter. It is also common around the world. If you hear of “dual band” the radios will most likely have 2 meter/440 band reception. I should note here the difference of dual band and dual receive.
Dual receivers pick up 2 signals at once (you will have 2 volume controls) and you can transmit on either band, you can only listen to one band, at a time, on a dual band radio. Between just those 2 bands you have over 500 frequencies to transmit on – enough to give you frequency anxiety. Compare that to the 40 channel CB and you have a major incentive to “move up” to ham radio.
At one time the FCC was petitioned to open the 11 meter (CB band) to a hundred channels or more (not including the current 27) but figured that would wipe out ham radio – not very many people are trying get a ham license as it is now. That problem is mitigated (slightly) now by eliminating the Morse code requirement for a ham license.
The other problem is that people have to be responsible for their actions – you will have a call sign and declare it every time you connect with someone. Other ham operators will not tolerate CB’er like talk (or antics) and their calls to the FCC get action.
The FCC takes equipment away from power running CB’ers - they jail someone bothering ham radio operators. Also remember that you represent America – having a general license allows you to “call the world” on your radio – the FCC will be listening (and other ham’ers) so talk nice.
There are levels of class of ham radio operator, right now Technician, General, advanced and Extra. Most people start at Technician but passing the general, advanced and extra tests at the same sitting would get you an Extra license right out the door at day one.
The main difference between the ham classes are the frequencies that you are allowed to transmit. Anyone can buy a ham radio (or scanner) and listen to any frequency, even military or police frequencies. Transmission however is a different matter – you are only allowed to transmit on the frequencies that you are certified.
If military or police are transmitting (during a disaster they may “borrow” civilian equipment) on ham frequencies – they have the “right of way” and you have to find another frequency. Although, if you want to get help, using ham radio will give you an edge over other “needies” since you can talk to the aforementioned folks.
Tech – privileges start at 6 meter and go up to 1.24 gigahertz. There are frequencies above 1.24 GHz available but there are so few operators using or radios made that I won’t bother you with them. I won’t bore you with all the frequency numbers as I provided a chart (old) with a graphic view of each band including numbers. I will point out that there are different uses – even within each band – specified for ham operators. For instance, the 2 meter band has SSB (“no FM”) set aside on some frequencies.
Now, all those counting the 2 meter freq. count are going to say, “there is only about a hundred frequencies available for FM voice”, and I say (FCC agrees) if a frequency is not being used – it is available for use. Very few people are using digital modes so you could use one of those frequencies to talk to someone. Although, there are enough frequencies to go around for the few ham radio operators out there.
General – get all the bands that are available to Tech operators (VHF/UHF) and a lot of HF bands too. In fact going from Tech to General gets you the most bands of any class upgrade. The HF bands can be a door to the world. There are HF only rigs that cost hundreds just for talking to someone in another country. Consider yourself a true ham radio operator if you get your General license.
Advanced – gives you a “few” more HF band spots with the license. If you wanted to talk to your friend (in another state or country) and you both had advanced privileges you could find an almost never used frequency. There are a lot of advanced operators out there, when the code requirement was cut many Generals took Advanced tests and passed. At this class you can transmit on 95% of the ham spectrum.
Extra – anyone having an Extra license is an over achiever. This class is the end of the line, top of the heap, all bands open license. Of course, if you think that Extra’s are hanging around the 5% of the airwaves – they are talking to our neighbors around the globe on every band.
Primer for Ham radio part four
by Guest Blogger on October 19, 2012 • 19 comments
Gear.
This guest post is by Michael C and entry in our non-fiction writing contest .
Ham radio operators have the unique ability to build their own radio. No other class of radio operator (commercial broadcaster, military operator) is able to do that. You could put together a bunch of recycled/junk parts and “talk” out of it – without FCC part 15 certification. Most ham operators buy their radios since the commercial offering has become so advanced. Modern DSP chips make HF radio more pleasant to listen to, digital tuning, preset bands, lots of buttons and back-lit dials. The big rigs that have more than 30 buttons can go for $10,000 (yes, Ten Thousand USD) and are aimed at the over achieving Extra who wants to win DX contests and soon to be divorced.
Ham radio operators have the ability to run their equipment at any power level. A CB radio can only transmit at 4 Watts of power, ham operators can run 2000 Watts if need be. Although ham operators are supposed to use only what they need to communicate effectively. Ham radios normally have 5, 10 and 50 Watt settings, the big “all band” radios have “dial a Watt” knobs to specify how much in single Watt increments but the top is about 100W. Need more power – buy a linear amplifier for lots of money, of course.
Ham radio operators have the ability to transmit in various modes. Did you learn Morse code as a young scout or have a computer? Not only can you transmit in Morse code but there are computer modes (PSK) as well. You are not limited to AM or FM (which includes SSB and narrow band FM) voice modes because there is also digital voice encoding. For TV watchers there is SSTV (Slow Scan TV) mode.
Ham radio operators have the ability to run remote (remotely operated) radio equipment. You may have heard of ham operators talking through “repeaters”. This is a dual band radio that takes a signal and re-transmits it on another frequency. The high frequency signal is just above the low frequency signal but far enough so there is no “cross talk”. The repeater can receive and transmit on both frequencies but not at the same time. Ham radios can usually catch the whole conversation because they have pre-programmed band usage. The ham radio knows the frequency it is on is a repeater only frequency. Repeaters are used mostly to contact other ham operators from farther away. I mentioned that all VHF/UHF bands travel in a straight line – that means if your behind a hill you can’t hear anyone. If it is your hill you could put your own private repeater on top and hear everyone. Most repeaters are put up by ham clubs which share the cost but allow all hams to use. Special goodies like radio to phone line hookup (making a phone call through your ham radio) are reserved for club members. It’s not too hard to join a club – you are already a ham operator, donations may be accepted. If you use a certain repeater a lot you may want to support them.
Ham radio operators have the ability to build their own antenna. This is also unique to ham operators. This is something that you really could do (unlike building a fancy radio) with some copper wire or an old box-spring. A whole book could be written about this (oh yeah ARRL did) subject but I will cover one aspect. There are “directional” antennas that will beam your signal in one direction. You can limit your broadcasts so that you are not heard in other directions.
Last thoughts
After you get your license – you are going to want to get a radio. Your choices here are so unlimited that I just have to say, “keep your original objective in mind”. Did you want to talk to your prepping friends or talk to the folks in Denmark? Both ends are achievable with an all mode/all band radio. Talking to your friends on 2 meter in AM (SSB) would restrict reception to only radios that can listen to AM-SSB signals on 2 meter. Talking to Denmark requires HF bands (and a General license) and AM mode. Be careful not to start “band collecting” just because you can transmit (legally) on that band. Then comes the “gotta sell some of these radios to get the radio that I really want” day. The smallest ham radio is a hand held or handy-talky some of which are smaller then a pack of cigarettes, the largest radio will make you feel like the captain of a star ship (what’s this “satellite” button).
For greatest OP-SEC try for a little used band, 1.2 GHz is little used because the radios are 700 to 1000 (USD) new. The UHF bands 222 and 900 MHz are little used because they are not internationally recognized and the 900 MHz is torn by garage door openers, walky-talkies, old cordless phones, etc. Use a computer program (PSK) to have the shortest transmission time possible. Use the AM mode if available – FM band scanners do not recognize AM signals. Use the least power for transmission – works good with solar power. Use a directional antenna, you can also reduce the power some more.
HAM RADIO EXPLAINED – sort of
by Guest Blogger on October 30, 2012 • 21 comments
This guest post is by Dave L and entry in our non-fiction writing contest .
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.)
Getting started in Ham Radio
by Guest Blogger on October 4, 2012 • 73 comments
This guest post is by Raybiker73 and entry in our non-fiction writing contest .
Not long ago, I read an excellent guest post on this site by Tom C titled “Understanding the Fundamentals of Radio Communication: Is Anybody Out There?” Tom pointed out the importance of understanding radio fundamentals, and provided some great starting points for anyone who wishes to obtain their amateur radio license.
As a recently-licensed ham, I understand how intimidating the idea of testing can be. I wanted to obtain a license for many years, but the test just seemed to be a bit too daunting. This past spring, I decided to finally jump in and give it a try… and I did it! Not only was I able to pass the entry-level Technician Class test, but I passed the mid-level General Class test as well. It took a bit of study, and it wasn’t easy, but it wasn’t impossible, either.
The other thing that I found intimidating was the Morse code requirement. Previously, each license level required an increasingly hard Morse code test in addition to the standard multiple choice test. However, the Morse code requirement is no longer part of the testing, which means getting your license is easier than ever before.
The hard part began after I passed the test. What radio should I get? Handheld or base station or portable? Should I build a dipole antenna or a beam antenna? Where do I get all this stuff, how do I put it together, and how do I get started actually USING it?
I’m sure I’m not the only one out there with questions, but I’m learning, and I’d like to share my experiences with those of you who want to learn as well. It’s not something we can complete overnight, but if we work together, I think we can figure it out. I’ll start with the first step in the process: preparing for the Technician-Class examination.
There are three levels of amateur radio license: Technician, General and Extra Class. The primary practical difference between the various license classes is access to frequencies. The FCC has established a series of amateur radio “bands,” or blocks of radio frequency to which amateurs have access. Technicians have limited access to some of these bands, Generals a bit more access, and Extras have full access to all bands.
So, you’ve decided that it’s worth a try, and you want to prepare for the Technician-class exam. The question is, where do we get started?
There are two books you will want to get before you do anything else. The first is the ARRL Handbook for Radio Communications (as mentioned in the previous article by Tom C). This is a book that will be on your shelf for many years to come, as it contains reference material and information useful to ham operators of every class. Think of it as your “Ham Bible” – if you’re looking for answers or inspiration, you’ll find it in here. This book is available from the ARRL at www.arrl.org.
The second book you will need is “Technician Class 2010-2014,” by Gordon West. West’s book provides the entire question pool for the Technician Class exam, all 394 of them (Don’t panic! Only 35 questions will be on the actual exam). Rather than just providing a list of questions and multiple-choice answers, West’s book organizes the pool into blocks of related questions, and provides the background information for each question. This book is invaluable in exam preparation in that it not only provides the entire question pool, but helps you to understand the rationale behind the answers. Where the ARRL book can be considered your Ham Bible, consider this book to be your Technician Class Textbook. You can find West’s book at Amazon or other retailers.
Finally, you’ll want to take some practice tests – nobody wants to go in cold, right? There are a couple ways to do this. Many sites offer online practice exams, but the best that I’ve found was the AA9PW site at aa9pw.com/radio/. There is a link on the main page there that will generate a practice test for any of the three exam classes, using questions randomized from the question pool. A practice test only takes about 5 or ten minutes, and I found that doing this a couple times a day when I had a moment to spare was a great help when it came time to take the real thing.
Practice test apps are also available for portable devices. The one that I found most useful was Amateur Radio Exam Prep: Technician, by Patrick J. Maloney LLC. This is available for iOS devices such as iPhone and iPad, and is available in the iTunes store. Exam apps exist for other platforms such as Android, but as I haven’t used them I don’t feel qualified to recommend any specific one. A simple online search will show a lot of apps for whatever platform you prefer.
With these three items in your arsenal – the ARRL book, the West book and a means of taking practice exams – you’re ready to take on the Technician Class exam! Again, it’s challenging but not impossible. If you study the materials a bit and take the practice exams, you’ll have no trouble at all.
Like most of you, I’m just starting on my ham radio adventure myself. In future articles, assuming the interest is there to support it, I’d like to go over the nuts-and-bolts of taking the exam, the basic electronic theories and components you’ll need to know, and preparing to upgrade your license if you so choose. I’d also like to take you all along as I jump into ham radio: choosing a radio, choosing and constructing antennas, and actually getting on the air to talk to people. I hope you’ll join me, and I hope to hear you all on the airwaves!
(disclaimer: any books or materials I recommend are ones that I’ve used. I don’t receive any compensation, nor am I in any way affiliated with any of the producers or publishers. I’m only stating what’s worked for me personally. Thanks!)
Getting started in Ham Radio, part 2 – wavelengths and watts and whatnot
by M.D. Creekmore on November 21, 2012 • 7 comments
This guest post is by Raybiker73 and entry in our non-fiction writing contest .
You can also read part one here.
So you’ve already decided on getting an amateur radio license, and you find yourself with a few questions. One of the first questions you have is probably, “What is all this ‘wavelength’ and ‘meter band’ and ‘HF’ stuff?” Or, maybe you wonder what that guy was talking about when he invited you to “check in to our prepper net down on 80, we’re at 3850.” Like most pursuits, ham radio uses some specialized jargon. Let’s try to clear up a few of the basics.
“What is all this crap?”
SURFING THE WAVELENGTHS
Ham radio operates on certain segments of radio frequencies, or bands. Just like AM radio is found between 540 and 1710 kHz, and FM radio is found between 87 and 108 MHz, ham radio has its own sections of bandwidth to occupy. These bands are generally referred to using the approximate physical wavelength of the radio waves. For instance, the “80-meter band” runs from 3.500 MHz to 4.000 MHz (3500 to 4000 kHz), as 80 meters is the approximate physical wavelength of a radio wave at those frequencies. Likewise, anything from 28.000 MHz to 29.700 MHz is considered the “10-meter band,” and so on. Remember, these are approximations, as wavelengths change with every change in frequency. The “band plan” designations just make it easier to group them together.
If you know the frequency and want to calculate the approximate wavelength, there’s an easy formula to get a fast-and-dirty result. Just take 300 divided by the frequency in MHz. For example, using this formula with 146.5 MHz, we come up with a result of 300/146.5 = 2.047. Correspondingly, 146.5 MHz is found in the 2-meter band. Another one, 14.150 MHz, would be 300/14.150 = 21.20. That means that 14.150 falls in the 20-meter band.
Frequencies in ham radio are referred to in either megahertz (MHz) or kilohertz (kHz). 1000 kHz = 1 MHz. You might hear somebody referring to a contact they made on 40 meters at either “seven point two” or at “seventy-two hundred.” That’s just two ways of saying the same thing. 7.2 MHz = 7200 kHz. Using our previous formula, 300/7.2 = 41.66, so that frequency is in the 40 meter band.
So, when that guy earlier asked you to join a discussion net “down on 80 at 3850,” you now know that if you tune in to 3.850 MHz on the 80-meter band, that’s where you’ll find him. Pretty easy!
“Basic list of frequencies”
WHAT’S THE FREQUENCY, KENNETH?
For those of you who are old enough, do you remember your old TV set that had separate dials for VHF and UHF? Those terms stand for Very High Frequency and Ultra High Frequency, and while your TV shows now come via cable or satellite, VHF and UHF, along with HF (High Frequency), are still terms you encounter every day in ham radio.
Although there are frequencies both above and below, the three most common in ham radio are HF, VHF and UHF. Ham radio HF starts at 1.8 MHz (just above AM broadcast frequencies) and goes the whole way up to 30 MHz, and includes the 160-, 80-, 60-, 40-, 30-, 20-, 17-, 15-, 12- and 10-meter bands. This is the frequency range that you’ll sometimes hear referred to as “shortwave.” Ham radio VHF starts at 50 MHz and goes up through 300 MHz, and includes the 6-, 2- and 1.25-meter bands. FM broadcast radio (87 MHz-108 MHz) falls in the middle of this segment. Ham radio UHF frequencies start at 300 MHz and run the whole way up to 3000 MHz, and you’ll find most users on the 70-cm and 33-cm bands. Great, so… what’s the difference?
The short answer to that question is “distance.” The HF bands are generally more geared towards long-distance communication, while the VHF and UHF bands are for more local communication. For example, in an SHTF situation, most of your communication with the outside world would be on the HF frequencies, and for local operations the hams in your group would likely be using handheld or mobile VHF radios to communicate with each other. Those rules aren’t written in stone – you can talk to someone just a few miles away on HF, and if conditions are right you can get out pretty far on VHF, but generally, lower frequencies = longer potential communication distance. For a person holding a technician license, most of your operating will be on VHF and UHF, where you have full privileges. Technicians have some very limited voice privileges on 10-meter HF, but other than that, if you’re a Technician who wants to use HF, you’re mostly limited to morse code. But, if you have your Tech license and you’ve read this far, you’re probably already chomping at the bit to upgrade to General and then Extra Class, which will open up the whole world of HF frequencies for you!
“Electronics formulas you need to know”
POWER TO THE PEOPLE!
One of the hardest thing for an aspiring ham to learn, particularly one without any electronics experience, is Ohm’s Law. While it might make your eyes glaze over just like high school algebra, it’s actually a very simple formula that you’ll need to understand whenever you’re building or troubleshooting something. It’s also required reading for taking your amateur radio test! There are many formulas that are part of Ohm’s Law, but these are the basics you’ll need to know to get started.
Any beginner’s electronics text will tell you that volts are electric potential, amperes are current, ohms are resistance and watts are power, but what does that really mean? As a kid, I was taught to think of it like plumbing: Volts are the water in the pipe, amperes are the water flow, ohms are the size of the pipe and watts are how much water you get out of the spigot. Lots of water, high flow rate and a large pipe will give you a lot of water in your bucket, while less water, low flow and a small pipe will give you a lot less.
Electricity works in much the same way (just don’t mix the two together!). Put more volts or current in the wire (more water or higher flow in the pipe), and you’ll get more out of the other end. Higher resistance (a smaller pipe) will let through less power than lower resistance. The chart above shows the easy way to calculate these figures.
For example, let’s say you have a 12 volt power source, and you want to generate 2 amps of power. How much resistance will you need in your circuit? As the chart shows, resistance = volts / amps. 12 / 2 = 6, so you’ll need 6 ohms of resistance in your circuit. So, you’ve got your 12 volts at 2 amps, but how many watts of power is that giving you. Power = volts x amps, so 12 volts x 2 amps = 24 watts. Easy! These two basic charts will get you started with most of what you need to know in your ham radio projects.
If you haven’t gotten your Technician license yet, now’s the time to get started. If you have, well, now’s the time to upgrade to General and then to Extra Class! The same resources available for Technician study are also available for General and Extra, so with a little bit of effort, you’ll have no problem at all. In my first entry we talked about licensing, and this time we went over some basics, so next time, let’s start getting some equipment together and then we can get radio active!
www.thesurvivalistblog.net/primer-for-ham-radio-part-one/