Seventy years ago this month, the duo shown here are working on a one-tube broadcast set shown in the January 1948 issue of Popular Mechanics.  The set used a dual 6SL7 tube as regenerative detector and audio amplifier.  It was built on a wooden ladder-style chassis, allowing the tube and coil sockets to be mounted neatly without need of any drilling.

The set was the first in a series of progressive receivers.  As later issues of the magazine came out, the parts could be re-used to make more complex designs.