This article describes a homebrew project in which a two-channel DC wireless receiver and transmitter are used to remotely select one of three antennas (two dipoles and a wideband vertical); switch a balun between the dipoles; and perform all this from the comfort of a ham shack. A second wireless receiver is used in a display to indicate the selected antenna.
Could I get by with fewer amenities and shrink the size, weight, and power requirements of my keyer to make it more portable when going on a mini-DXpedition? It was worth an investigation.
I certainly didn’t need another desk mic, but the prospect of building one from a $1 LED lamp and a spare mic cartridge was a project I could not pass up.
Believe it or not, there are powerful radio stations all over the world sending out messages to spies every day, and you can hear them with an inexpensive shortwave radio and a simple antenna. You probably won’t be able to decode them, but it’s a real kick to tune in these clandestine signals.
After retirement a few years back, I started collecting AA5 radios, restoring and selling them. People would ask whether they picked up FM and, of course, they did not. I started thinking about how to add FM capability without destroying the AA5’s AM operation. Here is my solution.
A few years ago, we brought you a story about a guy building ham radio antennas from aluminum crutches. Now, he's using cable TV coax for his dipoles.
The complexity and sophistication of the electronic hardware required to recover composite baseband signals in the FM band is beyond the capability of most experimenters. However, modern digital signal processing software, capable PCs, and inexpensive software defined radio (SDR) hardware can now be easily combined to receive the information in these broadcasts. Learn how to combine this hardware, software, and your PC to build SDRs to receive FM radio broadcasts and more.