The gentleman shown here is putting together one of three circuits built around a 6C8G tube from the October 1938 issue of Popular Science.

The first project was a battery powered receiver which used half of the dual triode as regenerative detector, with the other half serving as audio amplifier. Plug-in coils allowed the set to tune both broadcast and shortwave bands.

The second project used half the tube as a rectifier, allowing the set to be used on AC or DC household current.

According to author author, Clark Maxwell (not to be confused with James Clerk Maxwell of Maxwell’s Equations fame), the set was able to pull in several European stations from New York City.

Finally, the magazine showed how the tube could be used as a two-stage audio amplifier.

Battery operated receiver.

AC-DC Receiver.

Audio amplifier.