No. 3945 (Model 2)

Image Courtesy of Grant Kornberg, Technogallerie

Image Courtesy of Grant Kornberg, Technogallerie

Image Courtesy of Grant Kornberg, Technogallerie

Image Courtesy of Grant Kornberg, Technogallerie

Image Courtesy of Dave Slusarczyk // Check out his YouTube Channel!

Image Courtesy of John Jenkins | Visit the SparkMuseum!

Introduced in November 1922 for $35.50, the Atwater Kent No. 3945 (Model 2) is a landmark of early radio engineering. This three-tube "breadboard" receiver features a detector-two stage amplifier circuit powered by batteries, utilizing one UV-200 detector tube and two UV-201a amplifier tubes. To legally bypass RCA’s expensive regenerative circuit patents, Atwater Kent strategically sold the unit without the central variometer installed, a clever design choice shared with the No. 3925 Model 1. Board dimensions are 18.5" x 8.5".