A 3-Tube AC-Powered "Regen"
By Douglas D. Fox
During the 1930s, the regenerative receiver was very popular with entry level radio builders. Usually, these sets were battery-operated. This 3-tuber is an AC/DC set with a floating ground. Like any AC/DC set, the usual safety precautions should be observed. The use of an isolation transformer is recommended. (Editor)
I acquired this interesting 3-tube AC powered regenerative radio about three years ago from another collector. The set uses two Type 37 triodes for the regenerative detector and audio amplifier. A third Type 37 is connected as a half-wave rectifier (grid and plate are tied together). A resistor line cord is used to drop the line voltage to about 19 VAC, and the heaters of the three tubes are connected in series.
The tuning circuit is very simple, employing a single gang tuning capacitor and a plug-in coil for the Broadcast Band (BC). The BC coil was the only coil supplied with the set. The radio uses a regenerative detector in which the volume control adjusts the amount of regenerative feedback.
The front panel of the 3-tube regenerative radio.
A view looking underneath the chassis of the 3-tube regenerative radio.
There wasn't much to be done to restore the radio. After thoroughly cleaning the radio, I removed the front panel and repainted it a gloss black. The filter capacitors were replaced. After the set was reassembled and tested, it turned out to be a good performer on local Chicago metro stations, picking up several with enough volume to drive a high impedance magnetic cone speaker. The set has not been tested on shortwave, since no SW coils were available at the time of this writing.
Schematic diagram for the 3-tube regenerative radio.
I have no idea of the origin of the radio, but I do not think that it was home-brewed. Why? Because all holes, both in the chassis and front panel, are factory punched. It also seems that there was provision for more than one coil, since they are plug-in. There are no markings or any indication of a manufacturer anywhere on the set. Perhaps this was a training kit for a correspondence course? If anyone has information on this radio, please contact me directly. Thanks!
(Douglas D. Fox, 603 S. 12th Ave., St. Charles, IL 60174)
Doug Fox is an engineering technician for CX2 Technologies, Inc. in Burr Ridge, Ill. He has had an interest in antique radios that goes back to his junior high school days. Among his collecting interests are battery radios from the 1920s, early AC sets, Philco cathedrals, Bakelite table radios, and early hi-fi gear.