A QRP (Low Power) Primer

Welcome to the first of what I hope will become an annual QRP issue of CQ magazine! This month we are going to explore one of the most challenging, technically enticing, fastest growing, and definitely the most fun aspects of the ham radio hobby: low-power communications, more commonly called .”I know the magazine has a Guy”in the person of Cam Hartford, N6GA, so what am I doing writing about QRP? Well, it seems that Cam convinced our fearless leader Rich Moseson, W2VU, that it would be a stellar idea for me to do a primer on QRP for this issue! Thanks, Cam. Yours is coming, pal. Just wait!

Seriously, I have been playing the QRP game since 1965, when I first joined the QRP Amateur Radio Club International (QRP ARCI: ), the largest QRP club in the world. It wasnback then, of course, as the ideas presented by its founder, Harry Bloomquist, K6JSS, were pretty radical at the time. The club was formed to promote the intelligent use of RF power, specifying that members use only enough power to make and maintain contact (in keeping with the FCC rules of the day, which are still in force today). Initially, members promised not to use more than 100 watts of RF input power when they operated. It wasnuntil the latter part of 1979 into 1980 that the club membership voted to limit RF output power to no more than five watts, falling in line with other international QRP organizations such as the G-QRP Club in England and the VK-QRP Club in Australia. I am happy to report that in 2011 the QRP ARCI celebrated its 50th anniversary and continues to serve the QRP community and QRPers the world over.

A QRP (Low Power) PrimerWhat exactly is QRP? Glad you asked! The three letters, Q-R-P, originally were used on CW to tell another station to reduce your power,”or as an interrogative, I reduce power?”Somewhere back in the day, QRP became the abbreviation for low-power communications utilizing five watts output or less. So when you hear a ham talking about QRP, he/she is talking about full-blown ham radio done at or below the five-watt level!

OK, I know what youthinking: can anyone use only five watts and effectively communicate?”Fair question, so letclarify things a bit.

First of all, the FCC mandates that all CB transceivers use no more than four watts of RF output power in order to be legal in the U.S. If you can skip”(work stations well outside the normal 10-15-mile CB coverage area) with a CB set, you can also do it with five watts using a CW/SSB QRP ham transceiver.

To satisfy all you math geeks out there, follow this exercise: When working with RF power measurements, it is handy to work in decibels, or dB. Three decibels (3 dB) equals an increase or decrease of a factor of two. In other words, if you have a 10-watt transmitter and increase the output by 3 dB, your power output will be equal to 20 watts. Conversely, if you lower your RF power output from 100 watts down to 50 watts, you have experienced a 3 dB decrease in output power.

Now a word from our S-meter! Each S-unit on the meter is supposed to equal a change in signal strength of 6 dB or a factor of four (4 ... x2 for each 3-dB change). Therefore, if we assign S-9 as an indication of the strength of a received 100-watt signal and that signal drops one S-unit (from S-9 to S-8), you will have a decrease in power from 100 to 25 watts! Dontake my word for it. Use the dB formula:

dB = 10 log (P1/P2) or 10 log (100/25) = 10 log (4) = 10 (0.6) = 6 dB

Extrapolating further, we can then determine that a 12 dB drop in power (two S-units) will equal 1/16 the power of a 100-watt signal! Are things becoming clear now? I hope so, because what we have just gone over is at the heart of how and why QRP works.

Now back to our 100-watt transmitter/transceiver. Letassume that your 100-watt signal arrives at my receiver with a signal strength value of S-9. If you decrease the power by a factor of one S-unit (6 dB), your RF output power is now at 25 watts. Dropping the output to S-7 will give you an RF output of 6 watts! We are now within range of QRP (5 watts). Using the aforementioned dB formula, we find that dropping the output from 100 down to 5 watts actually equals a loss of 13 dB, or slightly more than two S-units. If you cancopy a signal slightly less than S-7, you need to find another hobby!! This is and why”QRP works.

There are those hams out there in radioland who say too short for QRP.”These folks either do not fully understand the mechanics of QRP or they have rejected the idea based upon misinformation. There is possibly a third reason: They tried QRP once and had little or no success. To these folks, I simply say give it an honest try using proven techniques and re-evaluate your findings. One thing is certain: Sloppy operating habits and inefficient station design (including antennas and feed lines) woncut it at QRP power levels.

Admittedly, QRP operation is not for everyone. Although weshown that it is certainly possible to communicate effectively with five watts or less, there is also the matter of mindset. You have to get your mind around the idea that first, it is possible for people to communicate at these power levels, and second, you can be one of them! This is where faith in your operating skills and your gear enters the picture.

QRP Operating Modes

While CW is the QRPermainstay operating mode, SSB and data modes such as PSK31, JT-65, Radio Teletype (RTTY), and Olivia can also yield many QRP QSOs.

Why is CW generally preferred? There are several reasons. Among them is the fact that CW is very easy to generate. After all, what you really are doing is just turning the transmitter on and off using a key, right? Another fact is that CW is roughly seven times more effective than single sideband (SSB) under similar band conditions. Essentially what this means is that your CW signals are seven times more likely to be heard than a similar SSB signal with identical band conditions.

While many of us prefer CW, we donreally burn up the airwaves with highspeed Morse. Quite the contrary: Most of the CW QSOs done at QRP levels are done around 15-18 words per minute (wpm), which is not all that fast, and plenty of folks go more slowly as well. With just a little effort you can learn the Morse code and be up to a reasonable level of proficiency in a few weeks. No, really . . . you can. There are programs on the internet, many of them freeware, that can teach you the International Morse code, and all you have to do is devote a couple of 30-45-minute practice sessions to the project each day.

Hardware for QRP

Now that we have covered the bare essentials regarding how/why QRP works and the modes of operation, lettake a look at the hardware used to generate our low-power signals.

QRP CW rigs are extremely easy to construct. Oh . . . one thing I need to ensure you realize is that QRP and building your own gear go hand-in-hand. As a matter of fact, one of the main motivators for people flocking to QRP is the massive number of kits available to QRPers. QRPers want to build things. While Heathkit shut its doors in the mid 1990s, others have stepped up to provide us with many innovative kits to keep us busy. QRP life is good!

On the other hand, you donneed to build your own rig to have fun with QRP. You doneven need to buy a dedicated QRP rig. You can throttle back your current HF transceiver or use an RF attenuator to drop your rigoutput down to QRP levels and not spend a dime! Neat, huh?

As an alternative, you can lurk on the various internet auction sites and find a used commercial transceiver auch as the Ten-Tec Argonauts or the Heathkit HW-8 or 9 transceivers for a decent price. There are also several excellent commercially built QRP rigs on the market at reasonable prices. Or, you can really be daring and buy a QRP radio kit, assemble it, and use it on the air. What better way to partake of the QRP experience than by using homebrew gear? Talk about pride in accomplishment! Also, letnot forget the factor.”What could be more fun than chasing DX or contesting and busting some pileups with a station youassembled yourself! Heady stuff, that!

As for a source of QRP kits, just Google the internet and stand back! Some of my favorite kit producers are, in no particular order: Elecraft (http://www.elecraft.com/), American QRP Club (http://www.amqrp.org/kitskits. html), W1 REXQRPME (http://www.qrpme.com/), Kanga US (http://www. kangaus.com/), Oak Hills Research (http://www.ohr.com/), KD1JV Designs (http://kd1jv.qrpradio.com/), Wilderness Radio (http://www.fix.net/~jparker/wild.html), and Hendricks QRP Kits (http://qrpkits.com/index.html), just to name a few. The kits sold by these manufacturers are designed to easily be built and their customer support is great.

All youneed to build most of these kits are the basic tools for a well-stocked electronics workbench, including: soldering iron/station, solder, solder wick or de-soldering tool, wire strippers, small wire cutters and needle-nose pliers, screwdriver set, hobby knife, nut-driver set, and high-intensity lamp. Kits are not hard to build, especially those from the manufacturers outlined in the previous paragraph whose manuals and instruction sheets are extremely well done. The key to building any kit is to take your time, read and then re-read the instructions/manual, and solder properly. More kit problems are traced to poor soldering technique than anything else.

If you need help or advice, there are many user internet groups that are QRP radio specific. Log onto Yahoo and do a search on QRP radios and/or a specific radio model and you are sure to find a group that will provide a treasure trove of information for the budding QRP kit-builder.

A QRP (Low Power) PrimerQRP Operating Techniques

So far wecovered and why”QRP works, and webriefly discussed the modes and hardware needed to get our collective feet wet in QRP. Now letlook at some operating practices that will definitely increase your chances of success.

To ”or not ,”that is the question (with apologies to William Shakespeare). Ita fair question. My advice is to call stations with fairly strong signals that are calling ”already, and leave your own ”for a time when you are more comfortable as a QRP operator. The reason is simple: The station that is calling ”will be listening for a return call. In addition, he/she immediately will recognize his/her own callsign, so the chances of your slightly weaker signals being heard are much better than if you are pumping away sending ”and getting no response.

Also be sure to pick a station that is transmitting at a CW speed that you are comfortable copying. When using phone (SSB), pick a nice strong signal not affected by atmospherics such as fading (QSB) or interference (QRN). Italso a good idea to pick a station in the non-crowded portion of the band (low QRM) to further enhance your chances of getting into the other guylog. In addition, there are frequencies around which QRPers tend to gather (see Table II), giving you a better chance of meeting a kindred spirit.

By picking and choosing your contacts, your successful QSO rate will skyrocket!

If you are using CW, do your best to send flawless code. Remember the FISTS motto: transcends speed.”Live by it! There is no excuse for sending sloppy CW, not with all the digital technology that is currently available. Learn your craft.

On phone, use standard phonetics for your call. Seven Sticky Zipper”is cute, but Seven Sierra Zulu”is not only better, itstandard. It can be ”by most of the non-English speaking world that inhabits the ham bands. Remember, DX operators are a diverse group and English is not always their primary, or possibly even their secondary, language. Standard phonetics will go a long way toward successful QRP operation.

While webeen spending a lot of time discussing CW and phone tactics, donforget the digital side of the hobby. PSK31, JT-65, and RTTY, along with other digital modes, are made for QRP operation. It takes very little RF energy to engage in a PSK31 contact. With advances in computer sound cards over the last several years, combined with the explosion of digital communications software that will run on laptops, assembling a QRP digital station is ultra-simple. The SDR Cube, a standalone digital station, is a great solution for the digital QRPer who wants a small station footprint and a rig to take on the road. The SDR Cube is the brainchild of George Heron, N2APB, who regularly thinks outside the box. The ”is approximately four inches on a side and contains the hardware/firmware which when combined with a Softrock RF deck yields a very compact, ultra-portable digital QRP station.

Software Defined Radios (SDRs) have allowed QRPers to push the envelope when it comes to adding operating features that were unavailable for low-end radios until only recently. Among the most prominent in the SDR group is the SDR Cube, the Flex Radio Systems 1500 SDR transceiver, and the Elecraft K3. Do your homework and find a SDR that fills your requirements at a price you can comfortably afford. Technology can sometimes be very expensive, so before you plunk down the plastic, talk to members of your local ham club and find out their preferences and the pros and cons of various SDR rigs. Also donforget to read the product reviews in CQ, QST, and on internet sites such as eham.net. The more information you amass before buying, the more likely you will end up with a radio set that you can live with and enjoy for a long time. The one thing SDR technology has done is make obsolete planned obsolescence! Simply upgrading the software in your SDR gives you a whole new radio. Aintechnology wonderful?

The QRP Bookshelf

One way to improve your operating abilities is to read. Thatright —read. The ARRL publishes several titles that should be the first books you reach for when you need information on ham radio in general and QRP in particular.

The ARRLLow Power Communications, the Art and Science of QRP, written by some guy named Arland, is now out in its fourth edition. All self-aggrandizing aside, this is currently the only book published in the U.S. that deals exclusively with QRP. I have been extremely blessed (not to mention lucky) to have authored all four editions. Feedback from the readership goes into the next edition because that is the only way to stay abreast of the changing face of QRP. The ARRL also offers several other excellent titles: The ARRL Handbook, the ARRL Antenna Book, and the ARRL Operating Manual are three books that absolutely need to be on your shelf. While these are not totally QRP-related, they are to”volumes you will repeatedly use in your pursuit of amateur radio.

Bob Locher, W9KNIexcellent book The Complete DXer, and his equally popular Year of DX," are also must-have volumes for your QRP bookshelf. Both of these books place you at Bobelbow when he is trolling the bands working DX. While I understand that not everyone wants to become a DXer, Boboperating style can be directly translated to the QRP side of the hobby. Learning how to read the bands, use propagation information, and select the best antenna all have a place in the QRPertoolkit. Bob shares all this information in his books and they are tremendous reads. Do yourself a favor and pick up one or both at the next ham-fest. You wonbe disappointed.

Various QRP clubs offer books and primers all designed to help the QRP newbie get comfortable in the hobby.

Alas, weout of room for this monthcolumn, yet we have barely scratched the surface of low-power communications, and specifically QRP. Speaking from personal experience, I have devoted most of my amateur radio career to QRP, and, contrary to popular belief, I donknow it all! Every time, every time, I get on the air I learn something new. Thatwhat keeps me involved with the QRP facet of our radio hobby. I hope that this primer has whetted your appetite to try under-five-watts ham radio. Remember, itthe operator, not the equipment, that makes the difference, especially in QRP.

One of my favorite quotes comes from Howard S. Pyle, W70E (SK): is no substitute for skill!”Now those are words to live by.

Specially for those who constantly makes any calculations, being in traveling, we suggest to use spetsmalny online the calculator which will appear the irreplaceable assistant the necessary minute. To use the calculator rather simply - it is not more difficult usual. Be convinced of it!

 

Share This Post

Recent Articles

Leave a Reply

You must be Logged in to post comment.

Powered by Remotesupport.com