H. P. Friedrichs (AC7ZL) Homepage
The Radio Room
Radio Operations Articles
Getting A Ham License
In the late spring of 2003, I decided to finally buckle down and go after a ham license. By mid July, I had passed all four elements and became AC7ZL. As a new ham, I can hardly claim to be an expert, but I can share with you the thought process, materials, and tools I used to prepare for the exams. I was successful, you can be, too!
Switching power supplies have a lot going for them, but they can be problematic in the Radio Room. Find out why.
The Department of Defense Research and Engineering is conducting a contest to develop a lightweight, "wearable" power unit to provide electricty for the ever-increasing variety of electronic gadgets that modern soldiers carry with them. Here are some thoughts on the contest, the challenges implied, and what kind of technology might actually do the job.
In the spring of 2007, I had the opportunity to visit San Juan in Puerto Rico. The trip was an adventure—all the more because I had decided to bring some radio equipment with me. Read about it here!
Introduced in 1959, the Titan missile was part of the war machinery that would help to assure a peaceful, if uneasy, balance between superpowers for almost four decades. The silos in which these weapons were based were slated to be decomissioned in the 1980's, but one remains intact and can now be visited by the general public. Even better, the site offers a special treat for those of us with an interest in radio!
Mysterious sounds, encoded in the signals that crackle on the shortwave bands, sometimes contain interesting weather reports, storm information, and even pictures! With simple equipment and inexpensive or even free software, this information can be captured, decoded, and interpreted. Try it yourself!
Follow this link for more information on this soon-to-be-released manuscript.
LEDs (Light Emitting Diodes) are everywhere! They've become essential components of everything from cars to computers, televisions to telephone networks, audio gear to life-saving medical equipment and more. If trends continue, they will eventually dominate all of domestic and industrial lighting. But where did they come from? You are likely to be surprised when you discover the origin of the LED, but even more so when I demonstrate how you can create a primitive LED with nothing more than a flake of industrial abrasive, a power supply, and a sewing needle!