C. 1918 Marconi 3-Piece Radio Proving Set * Large, Beautiful, Uncommon


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Large three-box proving set made by Marconi Wireless Telegraph Co. of America. The set is comprised of a primary inductance, a secondary inductance, and a tuner.

All three components are in excellent condition, with no damage or repairs. No chips or scratches in the hard rubber panels. All engraving is legible.

Positioned side by side, they measure approximately 28″ wide by 15″ deep by 9″ high. Combined weight is 37 lb.

Measurements of the 3 individual components are identical — approximately 9″ high x 9″ wide x 15 ” deep.

All three components are housed in matching solid mahogany cabinets with a polished piano gloss finish. The finish on all 3 cabinets is original. Minor marks in the cabinets (mostly in the back) consistent with age, but nothing distracting and no damage.

Each inductance box houses a long cylindrical coil. The coils are tapped at intervals. All soldered connections are clean and original. The resistance of the primary inductance coil ranges from 1.1 ohms to 9.1 ohms, depending on the tap selected. The resistance of the secondary inductance coil ranges from 1.3 ohms to 14 ohms, depending the tap selected.

The tuner houses two cased pancake coils spaced approximately 10″ apart.  When the front dial is rotated, the coils, which are coupled, change their position relative to flat copper wires embedded in the hard rubber standards.  The resistance of the front coil is 29 ohms. The resistance of the back coil is 14 ohms.

These are big, beautiful, historic pieces that were likely used in the development of different receivers manufactured at Marconi’s Aldene, NJ facility between 1918 and 1920.


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