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As the pantograph makes and breaks contact with the line, he says, it produces sparks and electromagnetic bursts that can “drown the entire spectrum of faint radio signals the telescope is devoted to study.”

Mr. Schmieder was part of a test of a third alternative: a system that feeds electricity to trucks as they drive, using wires strung above the roadway and a pantograph mounted on the cab.

A new feature is the remote-controlled raising and lowering of electric pantographs, the apparatus atop a train that connects with overhead wires.

Part of the overhead power system began to strike the pantographs, damaging the carbon strips that conduct electricity, Gallagher said.

The layout and size are fine, but its pantograph keys are really mushy and unresponsive and just don’t feel good to type on.