Friday, January 31. 2020Construction report QRP-Labs.com 50W PAIn June last year, when I talked to Hans, G0UPL, ordering his QCX kit at his booth at the Ham Radio fair in Friedrichshafen, he mentioned that there would be a 50 W PA kit coming out soon, and that stuck with me. Meanwhile, I noticed indeed that QRP is just no fun when no one is answering your calls—sorry for having to say this. I like to think of this as a kind of “Law of the Conservation of Effort”: If a DX contact is established, and one of the stations is QRP, then the other one is doing all the work and effort (in terms of operating a respectable receiving antenna and/or “having to crawl into the speaker”). Well, thinking of my main goals that led me to the QCX, which were
wouldn’t there be a better follow-up step than
So, I kept close eyes on the QRP Labs site in the recent months for signs about that PA, and finally, at the beginning of December, Hans announced that PA on the mailing list, and only about one hour later my order was through. I was one of the lucky ones that could include his enclosure kit before it went out of stock. QCX modsWhile I waited for the kit to arrive, I had time for preparation: The QCX needed a PTT mod to be able to provide a PTT signal to the PA; this is achieved by patching a stereo jack into the circuits (plus creating an outlet in the QCX’s enclosure) and adding a pull-up resistor. I also flashed the latest firmware release using an Arduino Uno as programming device, which might be a topic for a different blog post. The harder question to answer was how to get a cheap but still qualitative 20 V 5 A power supply for the PA. Luckily, I already possessed the Lenovo UltraSlim 90 W (20 V 4.5 A) notebook travel power adapter, which even included the option to use a wall socket or a standard automobile 12 V plug. Therefore, I could even go from a standard 12 V lead-acid battery. I only needed a non-standard DC barrel adapter, which took some extra time to arrive. While I was at it, I purchased a 3S LiPo battery pack with nominal 11.1 V to power the QCX itself with something lightweight; note that I measured up to 13.1 V fully charged, so using a fresh 4S pack might fry the QCX. The PA kit arrived after Christmas, and I was again looking forward to the assembly process, which promised to be not as lengthy as that for the QCX. It took me about ten hours nonetheless, mainly due to assuming errors where there had been none. I will now go over some specialties that I had encountered during the assembly. Continue reading "Construction report QRP-Labs.com 50W PA"
Posted by Stephan Paukner
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Quelle: BMVIT Dieser Eintrag wurde automatisch erstellt. Angaben ohne Gewähr. Friday, September 27. 2019Construction report QRP-Labs.com QCX-40(This time in English, as there isn’t that much mechanical vocabulary involved that I was too lazy to look up in the dictionary, as was the case with my report about building the folding hex-beam. Considering my root motivations that made me involved with ham radio, there were three main points I wanted to fulfill:
So, walking down the aisles of the HAM RADIO fair in Friedrichshafen this June, besides fetching my shiny new Begali morse key, I was looking around for the CW TRX kits, designed to be soldered and assembled by their new owners themselves. The first one I saw (model name skipped here deliberately) was already promising, but it lost against the QCX: The QCX is younger, it has less SMD components (only two, and they are already soldered onto the PCB), and it was way(!) cheaper, despite comparable features. The only advantage of the expensive kit was that one could change the band by replacing a small band-specific module. On the other hand, although the QCX is a one-bander only, with a price tag of only EUR 44.00, one could simply build another QCX for that other desired band. I decided to go for the 40 m variant, having the coming winter season in mind. As a beginner, it was also important for me to be able to tune the finalized TRX without any troubleshooting that requires advanced electronics know-how, involving signal generators and oscilloscopes. The QCX fulfills this by offering a built-in signal generator and an initial tuning routine that YL/OM follows by adjusting some trimmers while watching an amplitude bar on the display. AssemblyWhen the kit arrived with all its component parts, I was really looking forward to the assembly process. And indeed, it was a lot of fun, boosting my soldering skills with each installed component and checking each step with a jeweller’s loupe. The whole assembly took me about 20 hours, spread accross several tinkering sessions:
Continue reading "Construction report QRP-Labs.com QCX-40"
Posted by Stephan Paukner
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Quelle: BMVIT Dieser Eintrag wurde automatisch erstellt. Angaben ohne Gewähr. Tuesday, June 4. 2019Baubericht FoldingAntennas.com Hex-BeamIch habe zwar angekündigt, den Baufortschritt zu dokumentieren, bin dann aber doch nicht so erpicht darauf gewesen. Eher kann ich also rückblickend und vom Fazit berichten, denn Berichte wie der von diesem OM z.B. sind weitaus detaillierter. Alles in allem lässt sich sagen, dass die Anleitung präzise auf alle Schritte eingeht; es ist hilfreich, alles ein- oder zweimal genau durchzulesen, bevor OM/YL mit dem ersten Arbeitsschritt beginnt. Anfangs musste ich auf die Definition von Begriffen achten, wie: Was ist ein Element (= 2 Strahlerhälften + 2 Abstandsseile + 1 Reflektor), ein Elementhalter (= „Dreizack“ auf den Spreizern), eine Universalklemme (= Verbindung von Drähten und Abstandseilen zu einem Element)? Sehr erfreulich war, dass das Tragrohr schon komplett fertig geliefert wurde, das hätte nochmal Zeit gekostet; das Tragrohr ist ein Koaxialfeeder, bestehend aus einem äußeren Rundrohr und einem inneren Vierkantrohr, die voneinander isoliert sind. Ein Ende aller Strahler ist elektrisch mit dem Außenrohr verbunden, das jeweils andere Ende symmetrisch dazu mit dem Innenrohr, und zwar anhand einer durchs Außenrohr durch führenden Schraube. Der Zusammenbau benötigt seine Zeit, hat aber Spaß gemacht und war ohne besondere Überraschungen. Ich habe dafür inkl. Feinabstimmung allerdings 19(!) Arbeitsstunden benötigt, aufgeteilt auf mehrere Bastelabende bzw. -wochenenden. So ging ich vor:
Entgegen der Anleitung wollte ich die Schrauben nicht mit dem Hammer in die Verbinder der Spreizer hineintreiben, weil ich hierfür zu viel Kraft aufwenden hätte müssen und um das Material gefürchtet habe; die Öffnung war einfach zu eng. Ich habe sie stattdessen anhand einer Sicherungsmutter auf der Gegenseite schraubend hineingezogen. Selbiges dann beim Anbringen der innersten Spreizersegmente am Tragrohr: Das beschriebene „Eindrücken“ der Schrauben war mir schlicht nicht möglich. Das Aufklipsen der Elementhalter auf die Fiberglasspreizer ging mit Hilfe einer Wasserpumpenzange ebenso ohne Kraftausdrücke, äh, -aufwand. Continue reading "Baubericht FoldingAntennas.com Hex-Beam" Thursday, May 2. 2019I'm learning CWSince I prepared to get licensed as a ham one year ago there was always this CW (morse telegraphy) topic coming back to me. My impression was and still is that CW is where the elite meets. It is one of the oldest modes of operation, so performing CW is also about the preservation of historical knowledge. (I also admire technicians who still know how to maintain, build and troubleshoot steam engines today, for instance.) Building a CW transmitter is way easier than one that modulates voice, because in the first case you just have to switch on and off a constant frequency carrier, while the latter needs higher bandwidth and a tremendous signal processing logic, be it analog or digital—so, CW looks like a good opportunity to get into more advanced home-brew electronics, which is one of the things at the root of ham radio. Another aspect that resonated well with me was: It is easier to do DX (contacts over large distances) in CW, because the human mind can decode weak CW signals easier than a weak voice in the noise, and the other way round: Using the same antenna and output power, you can reach farthest by operating in CW (ignoring advanced and “highly digital” weak signal modes like the current fad FT8 that have their roots in astro-telemetry). It resonated well with me, because I realized I won’t be one of those hams that have a permanent antenna installation on a lattice tower, I also won’t be one of those hams that operate a 2 kW PA. But CW, I noticed, is one thing I can enable myself and one “expert tag” I could tack onto myself. Even another aspect is: For doing CW, you have to master something. In contrast, you don’t have to master being a “shopping queen” (buying rigs and antenna towers—but probably you have to master aquiring the money for that, hi) or using your voice or a digital signal as information carrier (ignoring how you learnt to speak or operate a PC). Learning CW requires effort, endurance and conviction over weeks and months, just like learning a musical instrument, a foreign language or any new craft. Your path consists of 1,000 hours of practice, period—there is just no way around that. You cannot just go out and buy yourself CW knowledge! (This is also a motivation for me to ignore phenomena like FT8, where the mastering consists of handling a desktop software that constantly breaks backwards compatibility. In addition, in emergency events I’d be glad to not also having to deploy a PC for off-grid communications.) So, that topic was always in the back of my mind, deciding I’d give it a shot if I ever got note of a CW course in my surrounding. Since there wasn’t one, I decided to try my first steps on my own using LCWO.net. But even learning the first three or four letters, just using that site without any guidance of an experienced CW operator, turned out to be a bad idea: I was totally overwhelmed by the (imo) high default speed, and gave up soon. Luckily, last fall I finally heard of a local CW course and immediately registered for it. Meanwhile, I know that choosing the initial listening speed has to be considered carefully, including terms like Farnsworth spacing. Also, typing on a keyboard is heavily distracting the learning process (unless you are really fluent in the ten-finger system), because you’re training a new reflex—and there are numerous other considerations and advices for copying that only an experienced CW operator (or Elmer) can give. This is even more true for learning how to send CW. For instance, the first long learning path is to actually know all characters (letters, digits and some punctuation), recognize them in a sequence of “random character garbage”, write them down while you’re already hearing the next character, and find your way back into the flow if you were stumbling—a huge brain trainer. Adding a new character into your learning pool might be a “one step forward, two steps back” procedure. I was quite quick in learning all characters (that are relevant for the federal CW exam), what took me from November to February. (I use my daily train commute to listen with headphones and write down onto paper, using this Android app.) This means I’m a few months ahead of my fellows: I already practice listening with 18–20 words per minute (90–100 characters per minute) full-speed, that is, with zero Farnsworth-timing—and not just random garbage, also English words, which appear way faster due to CW’s Huffman coding. According to our time plan we’d reach this level (at 16 wpm!) in June, and—sadly!—only after that we’d get to start learning how to operate straight keys and paddles—a yet different and complementary learning phase. We’ll see if I’m allowed to take a short cut, because I’m greedy. (However, I won’t be able to practice this during my train commutes, unless I want to do so under weird looks.) Although I’m not there yet, I get already recognized by my fellow hams, what I enjoy, because, as stated above, I won’t ever get recognized as “the ham with the fat rig”. All in all, it seems to take about one year until we’re finally up to getting on the air. So, hopefully I can do so this fall or a bit earlier. A positive thing is that the federal CW exam is indeed a checkpoint in this course. I’d actually only need that if I’d intend to operate CW in some non-CEPT countries. (Since 2004, CW is no longer mandatory for taking the ham radio exam in OE.) But, it shows the corresponding federal ministry that there are still hams eager to take this exam and that this mode of operation is still alive.
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