Vintage Radio Alignment: From Scratch (From Scratch Series)

The popularity of repairing and restoring vintage tube radios has highlighted the need for a variety of test instruments. A voltmeter and signal generator are essential for troubleshooting. A wide-band oscilloscope comes in handy at times for tracing signals in radio frequency and audio circuits. After repairing or restoring a vintage radio, the final step is often alignment. For AM radios, a signal generator and voltmeter usually give good results. But for FM radios, signal generator/voltmeter alignment does not always prove satisfactory. In this book, I present the theory and practice of AM and FM alignment both using a signal generator/voltmeter and a sweep generator/oscilloscope. Because obtaining a sweep generator is not inexpensive or easy, I also include instructions on how to build and operate the “WhippleWay Sweep Alignment Board” or WSAB for short. It incorporates both sweep generator and oscilloscope into a single unit. Because of their popularity, my focus is on “tabletop” radios rather than “console” radios. The former includes All-American-Five designs that make up most of the vintage tabletop radios still around today. The latter are large, floor-standing models with additional stages and more complex circuitry. Though not covered explicitly, most alignment procedures covered apply equally well to console models or can be readily adapted to do so.