I’m a big fan of new technology, but occasionally something ancient like my Zenith radio shows me how a twist on old technology improves a product design and user experience.  My grandfather Hale T. Shenefield’s 1950-vintage Zenith AM radio (G503 / Chassis 5G41) takes a routine technology of the day – tuning a variable capacitor by a string-and-pulley system – and uses the method advantageously to give the radio a simple operation and clean appearance.

Closed and ready to carry…

Open and ready to play!

For decades variable capacitors were used as the main tuning device in radios.  In the simplest designs these variable-position metal plates are connected directly to a tuning knob.  When you turn the knob, the amount of surface area between the plates sets would be varied, changing the capacitance and therefore the radio station.  Most radios used some sort of string pulley for purposes of industrial design – to move the tuning knob to a place advantageous for styling or use – while keeping the tuning capacitor on the main electronics assembly inside.  Some also would add a metal flywheel to smooth out the feel, or different sized pulleys to ease the turning motion, or provide more precise tuning adjustments.

Zenith tuning by string and pulleys.

This Zenith radio uses the fact that the tuning strings can be twisted to place the tuning dial on a flip-up panel.  The resulting design is very clean.  When the panel is closed, the dial is hidden, and the radio is off. Release the latch and bring the panel upright, and the radio turns on, with the dial revealed.  Tuning and volume knobs, previously hidden, are also now exposed.  When you turn the knob, the internal system of string and pulleys changes both the capacitor and the indicated frequency – it looks so simple!

Zenith radio with frequency indicator dial, volume and tuning knobs exposed.

The radio itself is modest – particularly in size – and it can run on AC mains power or a big internal battery.  I know my grandfather was very practical and frugal so I am sure the cost was reasonably modest as well.  On the other hand, the sense of style and class is presented boldly by a metal badge proclaiming “The Royalty of Radio.”  Zenith continued to innovate in the user interface area, introducing the first practical wireless TV remote a few years later.  Ultimately they lost the TV battle to the Japanese, after 14 years in court embroiled in a suit claiming the Japanese were dumping (selling at a loss) products into the US to steal market share.  The story ends (for now) with Zenith brand wholly owned by LG, likely to be used for eternity as a secondary brand for low cost products (not typically the ones with innovation).  Oh well…

The Royalty of Radio

© Copyright 2014 Stephen Shenefield