Seventy years ago this month, the August 1952 issue of Popular Mechanics showed how to build this extremely compact broadcast receiver. The set was named “The Salesman’s Pal,” as it was designed to meet the needs of the “honest-to-goodness salesman–on the road most of the time,” although it was also suitable for the once-a-year vacationer.

The set was a typical “All-American-Five” AC-DC set, but was small enough to conveniently slip inside a briefcase. Two recently available parts made the small size possible. The first was a Centralab Audet PC-150 printed circuit unit, which we might today call a predecessor of the integrated circuit, as it contained several resistors and capacitors in the same package. The other, which became ubiquitous in later portable radios, was the “Ferri-Loopstick,” a ferrite core antenna coil.

The article pointed out that while the set was not difficult to build, the limited space meant that it was not intended for beginners.