By Dave Finley, N1IRZ
Appeared in the Socorro (NM) Amateur Radio Association Newsletter, April, 2000
For a few years now, you've been hearing about the joys of QRP, or low-power operating, on HF. If you've been wondering what this is all about, or how you might try it out, it's now easier than ever, and not expensive at all.
Recently, I've been playing with a delightful new QRP toy that has shown me, once again, that you really don't need much power to work the world. With a mere three watts and a random-wire (read zero gain!) antenna, I've worked stations in Europe, South America and the South Pacific, including a DXpedition on Socorro Island in Mexico's Revilla Gigedo group -- a Socorro-to-Socorro contact covering 1,100 miles!
I did this with MFJ's latest QRP rig, called the QRP Cub, a kit available in versions for 80, 40, 30, 20, 17 or 15 meters. The Cub comes either as a kit or wired-and-tested, but I strongly urge anyone to try the kit version, even if you've never built a kit before. The completed CW transceiver fits in the palm of your hand and weighs only eight ounces.
This rig uses numerous tiny surface-mount components, but the kit version comes with those already installed on the circuit board. To complete the assembly, you simply install the conventional components that go through holes in the board, as well as the pots, jacks, etc. The result is that you get the benefit of all that surface-mount technology without having to strain your eyes and file down your fingers to work with it!
The kit comes with a Heathkit-style construction manual, with a box for checking off each step of the construction. As with any new product, the manual has a couple of glitches, but if you can't figure them out, check out the postings to the User's Group (see below) for the details. Assembly took me a bit under four hours, but some hams have reported finishing in as little as two hours. The only real skill required is soldering, and this kit definitely can be successfully built by beginners.
Alignment requires an RF power meter (an SWR meter with forward-power setting will work fine), a non-metallic alignment tool for the coil slugs, and at least one functional ear. I did not find the alignment critical at all, and heard signals when I first powered up, even before the alignment was complete.
On the air, the Cub is quite straightforward to operate. There's a power switch, a volume control and a tuning knob. Once you hear someone, the only thing to do is call them and work them! The receiver is quite sensitive, but generates little noise on its own, so the hiss level is pleasantly low. My 20-meter version covers 55-60 KHz of the band, and this "coverage window" can be changed to suit your preferences. The 80, 40, or 15-meter versions, for example, could be set up to cover the Novice/Tech CW portions of those bands.
The rig produces plenty of audio for headphones and will drive a small speaker quite nicely. The audio jack requires a stereo plug, or else you'll hear nothing, so you may have to replace the plug on your speaker. The Cub features fast, solid-state break-in, or QSK. The receiver is somewhat muted (by the AGC) during transmit, but you can hear even moderately strong signals "through your sending."
With its small size and very light weight, this is the kind of travel rig I've wanted for some time. An 8-cell AA battery holder will power it, and a monoband dipole can be cut and tuned to pack with the rig. Add a key and you have an HF station in only a couple of pounds or so! The whole affair will fit easily in a briefcase, carry-on bag, or backpack.
The QRP Cub kit is available from MFJ for $99.95 (the wired-and-tested version is $149.95). However, the QRP Amateur Radio Club International (QRP-ARCI) has made the Cub a group project, and you can buy the kit through them at the discount price of $85. In addition, ARCI is sponsoring a Cub Users Group. The Users Group is a great way to trade notes with other Cub builders, and get advice, including help from Rick Littlefield, K1BQT, the rig's designer, who is a frequent contributor to the mailing list.
If you haven't yet tried QRP, you just don't know how much fun you're missing. The QRP Cub is a great, and inexpensive, way to join this fascinating part of ham radio. Oh -- you say your Morse Code skills aren't what you'd like for working CW? Hey, talk to me -- I've got just the book for you!