The [id=285262979; Alexanderson Alternator], operated at a very low frequency, which equates to a very long wavelength, which in turn required an enormous antenna system in order to operate with any degree of efficiency. To give an indication of teh massive scale of this project, the antenna towers are 127 meters (about 419 feet) tall. Built during 1922-1923. The system operated at a frequency of 17.2 kilocycles, which has a wavelength of 17.4 kilometers (just under 11 miles long).

Such a large antenna system would have required teh use of many insulators, either glass or porcelain, but I have been unable to find any related information, so far.