Ninety years ago, the April 1926 issue of Radio In The Home magazine carried the plans for the “200 Mile” crystal set shown below.  The author describes the set in the following terms:

Many readers will be surprised to learn that a simple crystal set has given a fairly consistent nightly range of more than 200 miles. Yet this is not unusual; it is just the average performance of a well designed crystal set and has been done repeatedly this and the latter part of last winter.

From our location in Niagara Falls, New York, with an aerial and location no better than the usual, we have regularly listened to Pittsburgh, 200 miles, to Schenectady, 250 miles and to Chicago, 450 miles.

This record may seem out of the ordinary and indeed we ourselves were surprised at first. But the manner in which the first set and others of the same type, used on our own and other people’s aerials operate, has convinced us that the feat may be duplicated almost at will.

It then goes on to describe the set, emphasizing how low-loss components are used throughout.  Any detector could be used, but for best results, “it should also bear a certain relation (rather difficult of exact specification) to the input impedance. These conditions can best be met through use of the electrically controlled carborundum permanent detector (Carborundum Stabilizing Detector Unit).”

The Carborundum Stabilizing Detector Unit was manufactured by the country’s only producer of carborundum (silicon carbide), the Carborundum Company, which just happened to be also located in Niagara Falls, New York.

The carborundum detector does have the advantage of being permanently fixed, with no cat’s whisker to fiddle with.  It requires a reverse bias, provided by a flashlight battery.  The Carborundum Stabilizing Detector Unit included a potentiometer for adjusting the bias voltage.  So the listener accustomed to fiddling with the cat’s whisker could instead fiddle with the potentiometer.

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