QRP - When Less is More

by

Marshall G. Emm N1FN/VK5FN [First published in "73 Amateur Radio" Issue #474, May 2000]





About twenty years ago, when I first became interested in Amateur Radio I was Elmered by some old-timers who delighted in telling me stories of what the hobby was like "back in the old days." Not only did they have to walk ten miles to school everyday carrying their little brother and sister on their back, they had to pass a "real" examination, drawing the schematic for a triple-conversion radio from memory, designing a linear amplifier based on beer bottles, and send the entire text of the US Declaration of Independence at 30 wpm with no mistakes. They had to cut the firewood to make the fire to make the steam to generate the electricity to run their radios, which of course they had made themselves from a handful of paperclips, rocks, and spit. Twenty years farther down the coax and I'm the old timer, entertaining the current crop of newbies with tales from the Golden Age of Ham Radio. I'm sure they think my stories are just as far-fetched, but I have a big advantage because I can literally recreate that world for them, through the wonders of modern QRP.

By definition, QRP is simply low power operation, specifically with 5W of RF output or less. In practice it is a large and growing Movement within the ranks of Amateur Radio, a genuine Avocation for most, and a Way of Life for many. At a time when the ham population as a whole has been declining, the QRP fraternity has been growing exponentially, QRP clubs are thriving, and the support industries like kit manufacturers have gone from strength to strength. Believe it or not, a few years from now it will be apparent that in a scant two decades, QRP has grown from being a special interest to become the life-blood and mainstream of the entire hobby.

How can this be? Isn't working with QRP power levels a handicap? Not at all. It's a somewhat arbitrary restriction of the one technical aspect of radio that has consistently worked against the interests of the hobby. Take away power, and you are left with skill, inventiveness, challenge, and enthusiasm that are very similar to the attractions of the hobby in its earliest days. It all adds up to Fun with a capital F, and at very low cost.

QRP isn't much of a handicap.

The effectiveness of QRP communication, and the quality of QRP equipment, can be explained very easily with a little math. I hear you groaning, but it is very simple math and in fact you had to learn it to pass the Novice test. It's called the Power Ratio. Forget about logarithms and focus on the business end of the equation, the received signal. Signal strength is measured in S-points, which you can usually read directly from a meter on your radio. Your concern when transmitting is how many S-points you are generating at the receiving station. The more, the better, right? Wrong. In the first place, if your signal is perfectly copiable at S-7, increasing the strength to S-9 achieves absolutely nothing, except perhaps additional pollution of the airways. And this one is actually engraved in stone, more or less, in Section 313a of Part 97 (the FCC's rules for those who have forgotten): "An amateur station must use the minimum transmitter power necessary to carry out the desired communications." That says two things. First, if you have a perfectly good QSO going with an S-7 signal, you are breaking the law if you increase your power! Second, if all amateurs complied with the regulation, then most amateur QSO's would be conducted at QRP power levels!

Don't believe me? Ok, let's look at the power ratio in action. Say you are transmitting with 5 watts and a station gives you a report of S-5. Now double your power to 10W and what happens? Your power output has increased by 3dB and the received signal has increased by the same 3dB, which is... wait for it.... one half of one S point. Double your power again, to 20W, and the received signal is now one whole S-point stronger. Double it again, to 40W and we are at 1.5 S points. Again, to 80W and we are at 2 S points improvement on our original 5 W signal. 80W is near enough to what your typical "100W" transmitter puts out, and by now you should see what little difference an additional 20W would make. In summary by going from 5W to 80W we have increased the received signal strength by all of two S points. The reverse is true-- if you are copying an 80W station at S9 and he reduces power to 5W, you will still be copying him at S7.

But let's not leave it there. Start at 100W and add 3 dB at a time by doubling power- you go to 200, 400, 800, then an illegal 1.6Kw (that's section 313(b) if you're counting). We doubled power 4 times, picking up 12 dB or.... wait for it.... 2 S points. Talk about diminishing returns!

But don't take my word for it- try it on air sometime and see what happens. The only caveat is that the S-meters on most radios, if they are calibrated at all, are set for the standard S9 at 50uV input- at any other input, larger or smaller, they are notoriously inaccurate. Personally I think there's a lot to be said for honest reporting the old-fashioned way- in terms of perceived strength relative to other signals on the band- but that's another story for another time.

Money talks, and power walks

It is a generally accepted belief that adding power is simply the least effective thing you can do to improve your signal, and that's supported by the math as we've just seen. But power also equals money, and when you start talking Kilowatts you are talking big dollars. Not just for the linear amp, but the antenna, transmission line, and tuner also have to be able to handle the juice. Priced a 1KW antenna tuner lately?

It's probably fair to say that most hams realize how little benefit, relatively speaking, they will gain from investing in a 1.5KW setup. But at the same time, they have trouble coming to grips with the relative performance of their garden variety 100W transceiver as compared with, say, a 5W QRP transceiver.

The entry price for a 100W all band HF radio is real close to $1000 now. You can buy or build a good QRP transceiver for around $100. That, I suspect, is a major factor in new hams opting to go the QRP route.

Click to view in full size. Under the hood of a modern 5W single band CW QRP transceiver, the Oak Hills Research 100A, built from a kit.



Proof of the Pudding

It's not in the eating, with QRP, it's in the achievements. Last weekend a friend of mine cranked his "full gallon" 5W transceiver down to QRPp levels- 250mW output. He worked a station in PA, a distance of around 1500 miles from Denver, with one quarter of one watt output. That works out to 4000 miles per watt, and again it works both ways- all else being equal, yes he could indeed have worked a station in Eastern Europe, 12,000 miles away, with one watt. We do it all the time!

Another friend has worked DXCC at QRP power levels, and has already by mid-April 2000, put in the paperwork for DXCC2000. QRP Worked All States is a piece of cake, and I would bet a higher percentage of serious QRPers has done it than the HF crowd as a whole.

Also on the local scene, the Colorado QRP Club stages two separate operations for Field Day. One of them, the "Aloha site," is very laid back and casual, affording new members and other interested parties an opportunity to get on the air, try out their own radios, and generally have fun with no pressure. The other Field Day operation is about as serious as you can get, with towers, wire beams, a high altitude site, and the best operators we can find. The result last year was first place in 2-A, the largest category in Field Day. Not only that, we placed seventh overall. Only six out of the thousands of Field Day stations did better- and we did it with 5W.

Click to view in full size. The Novice/Tech station at CQC’s 1999 Field Day made a big contribution to the club’s success, racking up over 150 QSOs– all QRP.

My own introduction to QRP, within the first 6 months of my ham career, came when a visiting ham suggested I turn down the wick on my FT101E and "really put my antenna to the test." I succeeded in working a station in the US, from Australia, with half a watt.

All the good gear

QRP equipment can be very simple, but the fact that we are working with lower power circuits means that experimentation and inventiveness are possible for all of us. The QRP equipment industry is thriving, with several kit and accessory manufacturers enthusiastically supported by the market and new gear coming out constantly.

Quality? Can't beat it. Put your $100 home-built radio next to a $3000 Ginzu box and the QRP rig will clearly win more often than not. Surprises hell out of guys who have just mortgaged their XYL to buy the latest all-singing-and-dancing bells and whistles transceiver. But it shouldn't be a surprise, because the biggest part of what you are paying for in the "big rigs" is circuitry to make up for a front end like a barn door. Your typical QRP transceiver is thoroughly optimized for operation on a single band (or a few bands), CW only, and with very efficient signal processing from front-end to headphones. A good rule of thumb, which is proven by QRPers every day, is "if you can hear him you can work him." And we have better "ears" than many of those guys who can boil water on their linears.

I said CW only, there, didn't I? That's because CW is at the heart of QRP- it's what makes QRP possible as a hobby, and QRP becomes a very good justification for CW. The reason goes back to the math, but perhaps not quite as directly. Let me state this as a fact- all else being equal (operator skill included), CW has an 18dB advantage over SSB. If you read the power ratio stuff earlier, you can see that 18dB is a HUGE difference. That's about the best I can do in terms of math, because ultimately you are comparing apples with oranges, but perhaps I can at least explain the sense of it. A CW signal is either there or it is not, and that's something the ear and brain can detect and work with very easily. SSB transmits the human voice, which consists of a wide range of frequencies and a wide range of amplitude or volume. The result is that the power used to transmit SSB is spread out over a "bandwidth" of a couple KHz. All of the power in a CW signal is concentrated in a couple of Hertz. And in SSB, the peak power is used only on voice peaks, which are a very small percentage of the transmitted signal. So the 18dB figure is justifiable, if not exactly measurable (others will quote higher or lower figures, but it's all relative). In practice, especially when conditions are marginal, a 5W CW signal will work better than a 100W SSB signal. And again, you don't have to take my word for it. If you've worked much DX you know that often CW QSO's are possible long before SSB "comes in" and sometimes SSB never quite makes it. Even if you are not a DXer, you should be able to prove this to yourself very easily in half an hour on the air. If you are a real Doubting Thomas, do a real test. Get on the air with a buddy using SSB and reduce power until you can no longer copy each other. Switch to CW at the same power level, and amaze yourself at how much farther you can reduce your output and still communicate.

As you might suspect, there is not a lot of SSB QRP activity, but there is some, especially since we are experiencing good propagation on 10 and 15M, where there is next to no noise and less power is needed. In fact, a large number of long-time QRP CW operators are turning to QRP SSB as the "next challenge."

There are two other important things about QRP equipment.

First, it tends to be small in size, light, and capable of operation from a small battery. This means it is a natural for portable operation, backpacking, and even bicycle mobile. Many of us take a complete HF radio station with us when we travel. Including a simple light-weight antenna, the whole kit and kaboodle will fit in a briefcase with room for a change of underwear.









Click to view in full size. The Colorado QRP Club’s annual picnic features a “Run for the Trees,” where members take off from the pavilion and race to get a station on the air. The balloon-lift antenna worked.

Second, and finally, QRP transmitters are very clean. Again because we are dealing with low power components, we have very effective filtration of harmonics and other spurious emissions. The result is that a QRP transmitter is far less likely to cause interference to nearby TVs, stereos, and telephones. QRPers are right at the bleeding edge of "stealth radio," many of us living under restrictive ordinances and covenants that might cause someone less dedicated to just give up on ham radio.

The QRP Culture

A major factor in the continued growth and success of QRP is the cohesiveness of the QRP community. It is a community in all senses of the word, from local clubs to national organizations, special on air events, and above all an enthusiasm for communicating with each other that hasn't been seen in any other aspect of ham radio for half a century.

General radio clubs are dropping like flies, but QRP clubs are cropping up like mushrooms. There are several organizations with national and international membership, and local QRP clubs in almost every part of the country.

A year or two ago I went to a meeting of a "major" old fashioned metropolitan radio club, one that has been in existence since the 1930s. They now have a total of 120 members, of which 9 attended the meeting. The program was on "laser printers." The last meeting of the Colorado QRP Club was attended by 50 members. We had a station on the air, and a program related to actual ham radio.

The Internet has been very important to the growth of QRP. Just to give you an indication of how much is available on the I-way, a search for "QRP" on Alta Vista turned up 23,745 page matches.

There is an Internet "Reflector" called QRP-L which has become the main universal communications channel for QRPers. It's like a mailing list, where a subscriber submits a message which is "reflected" to all other subscribers. At the moment there are something like 3000 of them, from all over the world. QRP-L is a very good way to get "into" QRP. To subscribe, address an e-mail message to listserv@lehigh.edu. The subject doesn't matter. The text of the message should be SUBSCRIBE QRP-L your_name your_call.

Another good resource on the Internet is the Colorado QRP Club's web site, which you will find at www.cqc.org. You might even think about joining- to quote their pamphlet, CQC is "A Colorado Club with Global Membership." Their bi-monthly magazine "The Low Down" is worth the subscription cost, and if fact you will often see it quoted in 73.

If you are a reader, you will find QRP columns in the major magazines, and a number of books are available from the usual sources.

Did I say we are a weird bunch? If I did, I meant inventive and playful. A few years ago a well-known QRPer Chuck Adams K7QO (then K5FO,) decided that QRP-L members should get away from their computers and onto 40M once in awhile, so he invented the "QRP-L Fox Hunt." A single station is "the Fox" for two hours, and everybody else tries to work him, or "bag a fox pelt." The Fox Hunt has become an annual event, with Fox operations twice a week through the winter. I had the honor to be a Fox a few weeks ago, and believe me, you haven't worked a pile-up until you have had 150 or more stations calling you within the space of two or three KHz. They are all QRP, but many of them have signals of S-9 or better, and the "baying of the hounds" is just amazing. Sustained CW QSO rates of better than one per minute are quite common, and in my two hour stint I worked stations in 42 States.

A few weeks ago someone on QRP-L commented on the "elitism" of the First Class Operators Club, and the immediate result was the formation of the Second Class Operators Club, complete with motto "AGN?," member numbers, and a contest last weekend.

My point is that QRPers, while very skilled, dedicated, and inventive, are always mindful that the hobby should be fun. They do a darn good job of keeping it that way.

It's difficult to do a general article on QRP because the topic is so broad. In "traditional" ham radio we have special interest categories for antennas, construction, design, contesting, DX, awards, emergency communications, and so on. You can put QRP in front of every one of those topics, and it's only a slight reduction in scope, if any. I've written nearly as much as a Wayne Green editorial here, and kept pretty much on the single track of "QRP," yet I've barely scratched the surface. And at the best of times words can only convey so much, so why don't you try turning down the wick and seeing what you can do with QRP.... and what QRP can do for you. It will be like discovering Amateur Radio all over again.

Click to view in full size. A complete QRP station, capable of working the world, will fit in a briefcase.



