At $49 plus postage, the little single-band QCX transceiver from QRP Labs may be the best bargain in amateur radio today.[i] It not only works - it is a pleasure to use.
The compact rig (4 x 3 1/4”) has been thoughtfully designed by Hans Summers (G0UPL) with an awesome array of features including RIT, cw decoder, internal keyer, dual VFOs, even enough memory for several pre-recorded messages. All items are easily accessible and intuitive, with parameters set in the menu. For example, to change keyer speed, you simply push the left button and the current speed reads out, changed by turning the encoder dial. It even has built-in test instrument functions: signal generator, voltmeter, RF power meter and frequency counter. Beacon mode and GPS interface are also possible.
The audio filter is built around my favorite Hi-Per-Mite SCAF design by David Cripe, NM0S, and provides a narrow 200 Hz cw filter without ringing.[ii]
There are only four controls: the volume control (no on/off switch), the multipurpose encoder, and two small buttons that are used to access features such as RIT and keyer speed, and to operate the menu. By pushing the encoder, four tuning rates are available.
Output may vary a bit depending on the components. My 40M version put out about 4 watts with 13.8v DC input. (Kits are available for individual bands from 80M to 17M.)
Construction is straightforward, with one caveat: the extensive on-line manual admits that the 4-winding toroid transformer (visible in photo below) can be a bit challenging, but detailed instructions are provided. I received my kit mid-week and, without working on it obsessively, had it on the air Saturday morning. Alignment is simple, requiring no external test equipment. Note that you may have to remove some windings from the toroid transformer to calibrate the bandpass filter, as suggested by the alignment procedures. Since there are a number of variables affecting the inductance, the instructions have you put on a few more turns than you may need.
The unit can be built as a self-contained unit, with all controls built on board, as I did. Putting it in a case that way can be a bit challenging since extensions will be needed to be added for the switches and controls, but there are excellent examples and ideas linked to their website. However, toward the end of the instructions, there is a page on how to mount the main controls off the board. In fact, the PCB has been designed with connections for that, making it simple to do. If you chose to move the LCD off board, though, be sure to use short or shielded connections or you may pick up some noise from the processor.
The assembly instructions are some of the best I’ve seen – right up there and perhaps surpassing Heathkit and Elecraft. There are separate pages for most components, making it a very long manual (I used my iPad rather than printing it out).
I decided it looked too cool that way to cover up the components with a case. Initially I was going to put it in a Plexiglasss sandwich, like some of the transceiver kits from China on eBay. However, I wanted to build in a small mini-paddle, and didn’t want to bother with extensions, so I took a different route, described below.
I mounted the board on the inside flat cover of a 6x4x2” plastic box (Radio Shack 270-1806, though it may not be available anymore). The box itself becomes a protective cover for transport and storage (just for fun, I added a handle. Photo below). A thin magnetic strip is glued to the bottom of the mini-paddle and another to the plastic case top. That way the paddle can be pulled forward for use and slid back when putting the cover on. (See photo.) The only challenge with this was that the space between the paddle jack and the paddle was pretty tight. I considered wiring the paddle directly but instead took apart a 1/8” stereo audio jack and soldered the wires on so that it just fit in the space.
I also added a folding leg to the bottom so that I could tilt the rig for use. The leg was something I had once bought on eBay to use on a laptop.
Although it isn’t really necessary, I used a small piece of Plexiglass as a protective cover for the most vulnerable parts. To do that, I cut out a rectangular hole for the LCD display. The cutout isn’t all that neat, and I may redo it, but it works.
I did substitute a slightly larger knob for the encoder and fabricated buttons to go on the tiny printed circuit pushbuttons.
I’m happy to report that, unlike the uBitx transceiver[iii] that I was working on at the time, I had no problem with BCI from a nearby AM station with the QCX.
I made lots of contacts with this little rig and had some very satisfying QSOs, including several QCX users.
At $50 bucks, you can’t go wrong with this rig.
(I wrote this some time ago for QRP Quarterly.)
[i] http://qrp-labs.com/qcx.html
[ii] The Hi-Per-Mite is a kit sold by Four Square QRP Group. http://www.4sqrp.com/hipermite.php See my article about installing one in the KX-1 in the January 2018 issue of QQ.
[iii] http://www.hfsignals.com
[iv] See QQ Fall 2014 for my description of a zero beat indicator.
[v] http://www.wb3aal.com/Pages/K6XX/K6XXCWIndicatorKit.htm
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