Contrary to your initial impression, this is not an illustration of Junior helping Grandmother with her knitting. Instead, Grandmother is kindly obliging Junior in winding a coil for his new one tube radio. The radio builder is now almost a centenarian, since the illustration comes from the April 1937 issue of Popular Mechanics, which carried the plans for a simple one tube regenerative shortwave receiver.
While the set was designed for the beginner, the circuit used a dual triode 6N7, and the inexpensive set demonstrated a “DX getting” ability equal to many sets with several tubes. It had a tight bandspread which made it an excellent performer in the crowded amateur bands as well as the 19 and 31 meter broadcast bands.
One half of the tube served as regenerative detector, with the other half serving as an audio amplifier to drive he headphones. In addition to the 6 volt filament supply, the set required a B+ of between 45 and 135 volts. While a battery eliminator could be used to run the set off household power, the article recommended use of batteries for best performance.
The chasis consisted of a wooden base, with an aluminum front panel. For tuning, one of the variable capacitors was set to the approximate frequency, with the smaller variable used to tune in the station’s exact frequency.
Coil winding instructions were included for four coils, covering the 160, 80, 40, and 20 meter bands. With all of those coils to wind, Grandmother’s help was almost certainly appreciated.
An antenna of 40 to 50 feet was recommended, and the illustration here shows Father helping to install it. So that he can grow to become a centenarian, Junior is safely on terra firma while dad takes care of the climbing.