Atwater Kent Model 40

This is an early AC-powered, tuned-radio-frequency (TRF) set, c. 1927. It is housed in a metal “cake-box” style cabinet popularized by Atwater Kent. The power supply is housed in a separate rectangular can toward the rear of the cabinet. Like other AK receivers, this was a mass-market model and is frequently for sale on eBay. 

The radio has seven tubes, including the rectifier. There are three variable capacitors for RF tuning, but the three are ganged together with a metal belt, so there is only one tuning knob, not three.There are two audio interstage transformers. Like many such TRFs, it’s not unusual to find a winding on either or both of these transformers open. Modern replacement 1:3 transformers are available from RadioDaze or Antique Electronic Supply.

The horn speaker shown in the picture is a Magnavox Model M-1. It would have been more customary for an AK Type E, E2, or E3 speaker to be used with this set. The AK Type E speaker, about 18” in diameter, seems too large in proportion to the set, at least to my eye. The AK Type E2 and E3 speakers are smaller. Actually, any old-style, high-impedance speaker will work.

Because there were many AK models, from breadboards to consoles, they are interesting to collectors. The story of  Mr. A. Atwater Kent, from radio mogul to Hollywood gadfly, is interesting; you can search the Internet for the whole story.

© 2005 Doug Criner