IK5 PWO Mauro
Why QRP? Low-power operation is more popular than ever before. Why not join in the fun?I Why would anyone except a masochist want to operate with less than 5 W output? What possible attraction could there be? Perhaps it's for the same reason anyone would operate an amateur station in this age of global telephone systems and satellite TV. Maybe it's for the challenge of doing something a little different. Maybe it's for the thrill. But I can tell you, there's nothing quite like having a QSO with a Japanese, Russian, or rare DX station while running less power than a kid's nightlight! The QRP Q signal was created to mean "Shall I reduce power?" but has since been adopted by the enthusiasts of low-power operation as their banner. QRP has come to mean 5 W or less output for CW, or 10 W PEP output or less for SSB. Most amateur organizations and contests embrace these as the official QRP limits. Many of the same amateur activities that take place in the rest of Amateur Radio's domain are alive and well within the QRP community. These activities include constructing home-brew equipment, operating QRP stations, experimenting, DX chasing, and contesting.
You Can Build It The QRP arena is one of the few places where the average home-brewer still can make a decent showing. In this age of multistage, integrated circuit, super-sophisticated all-mode transceivers, QRP operation stands out as a home-brewer's dream. How many hams can hope to duplicate the operation of the latest HF transceiver on their workbench? Probably none. If, however, we change the rules by restricting the power output, it is certainly possible for nearly anyone with the ability to obtain a ham license to build a 5W transmitter. QRP transmitting equipment is simple and physically small. The same can't always be said for the receiver, however. A QRP receiver must do the same job as any other receiver, while usually in a smaller box. It is certainly possible to build an adequate QRP receiver by using minimal circuitry and integrated circuits-but it's not easy to duplicate a top-of-the-line commercial receiver in a matchbox. If you are interested in home-brewing, but haven't actually done much, I would suggest the QRP transmitters as a good first project. QRP transmitters usually consist of a few transistors, and for HF work, the layout is not particularly critical. Probably the toughest part is finding or building the coils and chokes. Even the coils are not a big deal once you've wound a few. Schematics and kits are readily available. They make it easy to get started. After you've put together a kit or two, it'll be a piece of cake to move on to "bigger and better" projects. If you do start with a QRP transmitter, you can simplify the circuit even further by opting for crystal control. It may not be as restrictive as you think. A fair amount of QRP operation takes place on dedicated QRP frequencies-making it easy to pick the crystal you need. By adding a trimmer capacitor across the crystal you can "pull" the resonant frequency slightly to the lower side of the crystal frequency (This is, in effect, a simple VXO circuit.) The crystal can be pulled from about 3 kHz on 80 meters to 10 kHz on 15 meters, depending on the crystal type and other factors.
Antennas Once you have a working transmitter, you'll need a suitable antenna. Which brings us to the question: What kind of antennas do QRP stations use? You may think that following the lead of low-power, simple transmitter and receivers, QRP antennas should be small and simple. This is definitely not the case. A QRP antenna system should be as efficient as possible. Many transmission lines attentuate the signal considerably before it reaches the antenna. If you have 5 W of RF output and a poor feed line, you could end up with only a couple of watts at the antenna! You should approach your QRP feed line as if it were being used for UHF or satellite work. You want to get as much power to the antenna as possible. Using a lossy feed line at kW power levels is tolerable; at QRP levels, however, the loss of every milliwatt becomes more critical. The antenna itself is also important. For best results you need the best antenna you can put up -- it's as simple as that -- a high-gain Yagi if possible, up high and clear. It's just as though you were chasing the farthest DX. My antenna is an EFHW 10/40 m, which is probably one of the best choices. But it's the best I can do considering aesthetics, ordinances, and neighborly relations. Even with my EFHW I've worked Japan and many other stations using only 5 W output.
Operating Skills Required If you want to hone your operating skills, QRP is for you. With only a few watts of signal to work with, it becomes mandatory to perfect your operating technique if you are going to work through that DX pileup. QRP is the radio equivalent of brain over brawn. But isn't a 1-W signal lost in the shuffle of more powerful stations? It's not as lost as you may think. A 1-W signal is only a little more than three S-units weaker than a 100-W signal. So, if your 100-W signal is S-9, your 1-W signal will be about S-6. And that's plenty of signal! For QRP operation, you must be able to find DX stations, be aware of when and for how long bands will be open and have a crisp and clear setup on both CW and SSB. You must be able to quickly assimilate a DX operator's technique. One of the primary skills QRP operation strengthens is patience. With QRP power levels you have to wait for the right moment and make your move. This means you must be alert and listening rather than transmitting. You have to be familiar with the bands, operating procedures of DX stations and other QRP operators. All this takes a bit of patience, practice and listening.
How Do I Do It? Okay, let's say you just want to operate QRP without building any special equipment. That's easy, just turn the power down on your 100-W transceiver. This requires a power meter or some other method of determining your output power. This adjustment is dependent on your rig, and may be as simple as reducing the RF output control or as complicated as retuning the transmitter for reduced output. Here's a neat experiment that will introduce you to the realm of QRP operation in a gradual fashion: cut your maximum output in half and operate at that power level for a week or so, then cut it in half again. Continue cutting power until you're down to 5 W. I'm sure you'll be surprised, as I was, at how well you can communicate with reduced power. In many cases, the operator on the other end can't tell the difference.
A Few More Advantages There are a couple of other advantages of QRP operations that aren't so obvious. Because you are operating with a minimal power output, your transmitter will probably last "forever." Your electric bill will be less -- especially if you stop using your 2-kW space heater. The other non-obvious advantage is that you won't overload the front end of your neighbor's television. It's a pretty rare occasion when operating with 5 W causes interference.
Contests and Awards The bonus multipliers and points for QRP contest operation have gotten many hams hooked on QRP. Operating "QRP battery power" for Field Day gives a multiplier of five. You only have to make one contact for every five QRO QSOs.
What's Left What do you do once you've completed QRP DXCC? How about milliwatting? Milliwatting is operating at less than 1 W output. Once you've perfected your QRP skills and equipment, this is the next challenge.
73's de GØBUS