Battery Baby Superhet

Designed by W. T. Cocking and published in the October 7, 1932 issue of Wireless World, the Battery Baby Superhet was the battery-powered counterpart to the A.C. mains version introduced two months prior. Developed in direct response to reader requests from constructors in rural or off-grid areas without electric lighting mains, it adapted Cocking's single-valve pentode frequency changer architecture for battery operation.

Key Technical Features & Battery Innovations:

• Battery Single-Valve Frequency Changer: Employed a Mazda Pen 220A pentode as a self-neutralising frequency changer, biased negatively by 1.5 V, eliminating an extra valve stage to conserve filament power.
• Ultra-Low Current Consumption: Carefully designed to run from a standard 100 V high-tension battery with a total H.T. current drain of only 10 mA, making superheterodyne operation economical for battery users.
• Automatic Tone Correction & Selective Filtering: Utilised two-stage pre-selector bandpass coupling followed by 110 kHz I.F. bandpass transformers (Wearite W.W.I.F.). Sideband cutting in the selective I.F. stages was automatically compensated by the high-frequency response characteristic of the Pen 220A output pentode.
• Ganged Volume & Bias Switching: Volume control was achieved by varying the grid bias on the VS2 variable-mu I.F. valve. The bias potentiometer switch (S1) was ganged directly to the L.T. filament switch (S2) to prevent the bias battery from discharging when turned off.
• Local-Distance Switch: Features a rear-mounted local-distance toggle switch (S3) that inserts a 50 Ω shunt across the aerial input to prevent front-end overload when listening to powerful local broadcast stations.

Donde encontrará 9 modelos, 5 con imágenes y 6 con esquemas.
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