标签: ham

You sure have had your own A-Ha moment. The Merriam-Webster dictionary defines it as "a moment of sudden realisation, inspiration, insight, recognition, or comprehension." But I'm taking it one step further— a-ha! with an exclamation point. This is a more dramatic realisation. It's the moment when you discover a great truth, when something that was complicated or unpredictable suddenly becomes clear. As engineers, I'm sure we've had many. One of my first a-ha!s came in grade school. I was a hobbyist, and I enjoyed creating things from the local Radio Shack, even though I didn't know why they worked. I had hoarded quite the collection of resistors, capacitors, tubes, and speakers. I could read the colour bands on a resistor to get its value, and I had rudimentary soldering skills, but I didn't know how to design anything. One day, my older brother, who had been a Navy technician, explained Ohm's Law to me. A lightning bolt ignited in my head. You mean, there's a relationship between voltage, current, and resistance? That makes a lot of sense. And the world became a little bit more understandable. Building a circuit was a little less about pleasing the electron gods and a little more like engineering. I've had several of these moments since then. Calculus was a key ingredient to many. Though I knew formulas from high school physics, calculus enabled me to derive the formulas. As a ham radio operator, I knew how to calculate the resonate frequency of an LC network.   But I didn't know why that was the resonant frequency. With calculus, I was able to derive it myself, and I discovered why it also explained the resonant frequency of a pendulum or a spring and mass. Calculus explained that the current through a capacitor was proportional to the first derivative of the voltage. Suddenly, first-order differential equations explained time-domain and frequency-domain phenomena. This was another a-ha! moment. I've had many since then. Boolean logic explained digital circuits to me—no longer a mystery. A more recent a-ha! moment came when I learned how WCDMA worked. In retrospect, all these things seem obvious, but I can recall the very day that each of these a-ha! moments came. Science and engineering aren't the only subjects that have created these moments. An Economist article about international trade led the reader through a simplified two-party, two-industry model, where one party had a productivity advantage for both industries, and the other party had inferior productivity for both. Much to my surprise, simple arithmetic in the example showed that both parties produced and acquired more goods than either one could have done by itself if trading could occur between them. Until I had done the math, I had assumed trade was only advantageous if each had an absolute advantage in some industry. This was the principle of comparative advantage—and another a-ha! moment for me. I remember the day I did the surprising arithmetic. What about you? I'd like to hear about your a-ha! moments. Larry Desjardin Consultant  

One of the gateway drugs into electronics has traditionally been ham radio. In the past I've commented on its decline. But things have changed. The ARRL ( www.arrl.org ) reports that as of late last year there are now 700,000 licensed hams in the United States, an all-time high. That's up from 285,000 in 1971. How much of the increase can be attributed to the relaxed licensing requirements? Morse code is no longer needed. The test questions come from pools that are on-line, making it easier to master the material than of yore. I got my Novice license as a teenager; back then one had to pass a 5 word-per-minute (WPM) code test in addition to the written exam. Novices were limited to code on the HF bands, so that requirement made a lot of sense. And the limitation made sense as well, as a code transmitter is a very simple thing indeed which nearly anyone can build. Some time later I upgraded to General, but was never able to get beyond the 13 WPM needed for that license. The highest grade is Amateur Extra, which required a blistering 20 WPM. One pal could copy at 40 WPM; he didn't hear the letters, instead copying entire words like listening to a second language. It was astonishing to watch him listen without taking notes, chuckling at the jokes, and keying out a high-speed reply. There's been a lot of debate in the ham community about the relaxed standards, and plenty of hams feel they bring people into the hobby who really don't know much about electronics or the hobby. I'm sure plenty of new hams are weak in these subjects. And that's the reason to award them licenses. Bring them in, mentor them, let them experiment and learn and eventually become, as hams say, an Elmer . Last month I had a little spare time so, since there's no longer a code requirement, took the Amateur Extra test. I boned up a bit; the electronics is easy for an EE but one does have to know some of the rules and customs ( e.g., "Amateur stations may not transmit in which of the following frequency segments if they are located north of Line A? "). On test day one other person was also taking the Extra exam. We chatted and he complained that he just didn't understand reactance and resonance in series and parallel circuits, but was hoping for a miracle. It didn't appear, and, somewhat dejected, said he was going back to the books. That sure sounds like a success to me. His current, lower, license has him interested and active, and the allure of the higher ticket means he is determined to learn some electronics. For me, ham radio's attraction was originally mostly in building radios. No longer; now I have a commercial transceiver that I only use when operating maritime mobile on our sailboat. But a lot of hams continue to make their own equipment and the magazines always have plenty of cool projects. It's possible to get on the air with very cheaply by building your own radio. And, that DIY approach is a fantastic way to learn electronics.