No. 4066, 4205 & 4275 (Model 7)

The Atwater Kent No. 4066 (Model 7) Receiving Set, introduced in early 1923, this model was a five-tube set, the first in the line with this configuration, operating on a Tuned Radio Frequency (TRF) circuit. Its massive improvement over the Model 6 (four-tube) and earlier models was the addition of a second Radio Frequency (RF) amplification stage, resulting in a configuration of Two RF Stages, one detector, and two Audio Frequency (AF) amplification stages. The tube line-up often comprised five UV-201a tubes (or four UV-201a and one UV-200 detector). By employing two tuned RF circuits, the Model 7 dramatically increased both sensitivity and selectivity, effectively eliminating the need for a regenerative circuit altogether

Later in the production run, they switched to part No. 4205 signifying the replacement of the No. 3815 TA Detector, 2 Stage Amplifier for the newer No. 4135 variant. One final version was released June 5, 1923, part No. 4275, this was a substitution of the No, 3902 Detector for the TA Detector, Two-stage amplifier. These were the final single-stage detector units produced by Atwater Kent. Board dimensions are 26-1/2" x 8-1/2".

Model 7 - Type 4066 | Phil's Collection

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 Grant Kornberg, Technogallerie

Image Courtesy of Grant Kornberg, Technogallerie

Image Courtesy of Grant Kornberg, Technogallerie

Image Courtesy of Grant Kornberg, Technogallerie

Image Courtesy of John Jenkins | Visit the SparkMuseum!