The plans for this four-tube superheterodyne shortwave receiver appeared 70 years ago this month in the May 1950 issue of Radio Electronics.

According to the author, the set was the equivalent of a six-tube set, and was pulling in hams on 20 meters from Maine, California, and the Florida coast, all at loudspeaker volume. The trick employed is visible in the picture above, namely, the wire wrapped around the first IF transformer. This was connected to the grid of the 12BA6, and increased the gain through feedback. Plug-in coils were used for band switching, and the author provided coil data for 80, 40, and 20 meters.

The author was Homer Davidson, whose name is familiar as a fairly prolific author of radio books over the years.