• Number 1 on yourFndbKken Welcome, Newcomers! WHAT IS QRP? Amateur radio lingo is full of abbreviatio ns and code words. which evolved in the days of CW (Morse Codej-only communications. Many common statements and questions, such as " 00 you copy?", " My location is ...", "Please send more slowly" , etc.. have been reduced to three-letter statementsJ questions beginning with " Q." This gave CW communications-a much slower mode than spoken (vvoice"] communicauons-, greater efficiency. QRP means " reduce your power." Hams who enjoy low-power operation became known as Q RPers. The unofficial maximum power level for QRP operation is 10 Wall s. One Watt or less of transmitted power is called Q RP operation. AI first , many hams ask , . ' What's the point in QRP operation? " Mayhem often reigns on the bands during periods of good propa~a· tlcn. with some hams ru nning a full gallonplus battling it out. " How can the little gun hope to compete?" " W hy would anyone want to be a little gun? " To be sure , the re are reluctant ORPershams who make do with the equipment they have until they save up enough to run out and buy a 100 Wall output ri~ andlor a linear amp. ORP has a large devoted following, however. There's obviously much more to ORP than first meets the ea r, as this issue will auempr to show. The Elegance ofQRP A ORP statio n can be very small-the re arc QRP transceivers that can fit in the palm of you r han d! O RP rigs a rc muc h si mple r devices than their high -powered brothers, since there arc fewer stages of circuitry in the rig to step up the power of the sig nal and ensure signal linearit~ and purity. Ore- or two-afternoon O RP transceiver projects abound-Mike Bryce' s Q RP column is full of 'em. For hams who actually want to apply the electronic theory they lea rned (or memorized ) for their ex am, building a ORP rig is a great place to stan -very little ca n match the thrill of making a OX co ntact on a piece of equipment that you've built yoursel f! C raft Iru..lead of Kilowatts Let's say you ' ve built your pocket-sized 5 Watt rig on Friday night and Saturday, and hanker to get on the air on Sunday. You know, however, that when propagation is good. the bands are o ften wall-to-wall booming sig nals. What to do? QRPen; have to be a tenac ious breed, hut they soon learn that power is not the on ly factor in making a contact . They bag many of their contacts whe n a pa rticular band just opens up, before most othe r hams become aware of it. This doesn't mean that ORPers sit by their rigs 24 hours a day-many band openings are predictable . A Q RPer soon be- 4 73AmaleurRadio . June, 1989 comes skilled in the science of propagation . The science is far from exact . There are unpredictahle bands, Ten meters is often closed, especially during low sunspot activity, but it can open up very suddenly at different times of the day . This band needs more monitoring, but then the chances are better that fewer people will become aware of its opening, and the QRPer has a longer opportunity to work OX . When propagation is good, you r signal ca.n be milli watts and still get a good report from a OX station. A Little Antenna Math A QRPer' s best edge is a high -gain antenna system. Improvements here pay dividends at both ends of the path-receiving (vhearlng") and transmitting (vtalking"). What docs gain mean? Gain is simply a reio , usually expressed in decibels (dB). When you talk about an antenna having a certain ga in, you must specify gain over a reference anrcnna. Logically , gain relates not only to the errecttve radiated powers (ERPs) of a pair ofantenna systems, but also to the received signal gains of the same system pair . An antenna's ERP increases logarithmical Iy with its gai n. Here's a handy rule of !humb: every 3 d B gain increase doubles the ERP. For example, a 3 dB antenna has twice the ERP over a given reference; a 6 dB antenna has four times the ERP over tbat reference . A 9 dB antenna?-eight times the ERP! What's a good reference antenna? One o f the most common ham antennas is the If.z . wave dipole. To note it as the reference, we tack a "d" on the end of "dB." Ten dBd gain is a reasonable figure for a typical directional beam antenna that you can bu y for a few hundred dollars, or build for less . By the above logarithmic scale, you can GLOSSARY OX- Abbreviation for long Distance. DX for the HF bands is typically tra nscontine ntal. ERP- The power measure of the wave energy that radiates from an antenna that is the product of the input powe r into the antenna system and the net gain of the antenna system. Full.gallon-Ha m jargon lor a kilowatt of output power. HF- High Frequency. Refers to the 80-10 meter (3-30 MHz) bands . 160 meters (1.8-2.0 MHz) is US Amateur Radio's only Medium Frequency (MF) band. linear Amp-Short lor linear amplifier. This device takes an input signal and increases its power without (ideally) changing any of its other characteristics. linearity-An expression of the resemblance between the input and output signals ot a circuit. The better the linearity 01 a circuit, the ese it distorts a s ignal. Open up-Ham jargon meaning " provide good propagation ." intuit that 10 dB is about 10 times the ERP gain. This means that the operator feeding IO Walts into a IO dBd beam has the same chances of making himself heard to that OX station as the op putting 100 Watts into his dipole! Can IO Watts into a to dBd gain antenna really compete with the rest of hamdom? You bet! Most hams live in areas that restrict antenna systems. A city lot may not provide room for more than a dipole or a vert ical antenna. (A venical has similar gain to a dipole). Most hams don 't run more than 100 Watts into an antenna system since that is the typical limit for an unassisted transceiver, and linear amps are too pricey. Clearly, a QRPer with a good antenna system is really in the running! Hats OfT to QRPers The finest point of QRP operation is that it forces the ham to think . He has toexperiment with his equipment- installing narrow Illters. improving the ga in of his antenna system, etc.-and learn ahout propagation. The QRPer avoids the all-too-easy solution of cranking up the power to get through the crowds, which very easily leads to crowd ing out others. He shows courtesy to his fellow hams by almost never running more power out than necessa ry to conduct a contact (which is, incidentally, an FCC rule!). This is what separates the QRPers, who practice two critical mandates of the hobby-advancing the state of the art and frate rnal goodwillfrom the emerging throng of appliance ope rators who treat the linear amp as a cure-all . This issu e has a host of simple QRP transceiver construction projects to get you act ive o n most o f the HF bands . Happy home-brewing , and let us hear from you!1iII ...de NSIB Propagation- The transfer of energy (in this case, e lectromagnetic energy) through a medium, such as the atmosphe re or space. Purity- Most often an expression relating the power of the fundame ntal frequency of a signal and the power of its non-Iundamentallrequencies, such as harmonics. The purer a signal, the more pronounced its fundamental relative to its non-fundamentals. Rig - Ham ja rgon for transceiver. Transce iver- A radio set that contains a receive r and a transmitter in the same chassis.
QRM EdlfOflal Officft woe Centll' Hancock NH 03449 pl>ooe: 803-52$.4201 Adveftlalng orr~ WGEc.nl.. Hanc:odI NH 034
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