My last post talked about how QST covered one the technical advances 100 years ago—the move to undamped wave transmitters. The October 1966 and October 1991 issues of QST also had interesting articles on new technologies of the day. The October 1966 issue featured the article, “Field Effect Transistors: What They Are, How They Work.”
Field-effect transistors (FETs) are, of course, now an important part of nearly every amateur radio set. In 1966, however, they were cutting edge technology. I’m not sure when they first became available, but the article notes, “A recently introduced semiconductor device called the field-effect transistor, or FET…”
The nice thing about articles from this era of amateur radio is that they were very descriptive. This article starts out by describing how junction diodes work, which leads to a discussion of how junction FETs work (see the diagram below), and finally how insulated-gate FETs work.
Also included are some typical characteristic curves and some circuit examples. Great stuff if you’re just learning about FETs or want to review what you know about them.
The next breakthrough in 1991: DSP
Dave, K1ZZ, hit the nail on the head in his October 1991 editorial when he wrote, “It’s pretty clear that the next major development to hit our ham shacks will be digital signal processing (DSP).” He couldn’t have gotten it any more right. After more than 25 years of development in DSP, nearly all of our radios use some form of DSP, and some of them are just one big digital signal processor.
Some hams wax nostalgic about the “good, old days” of tubes and analog circuits, but not me. DSP makes amateur radio a lot more fun.
Also worth noting in this issue is the Audio Filter Roundup. In this article, Jim, KR1S reviews the J-Com Magic Notch Filter, the Modular Systems Smart Filter, and the JPS Communications NIR-10. The first two are analog filters, the third a DSP filter. None of these products are still available, nor are the companies still in business. Perhaps that was an omen of things to come.
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