TRISULASLOT Thus the alternator output frequency is "locked" to the tuned circuit resonant frequency. Nowadays, it would be technically possible to construct an Alexanderson alternator operating at higher frequencies (for instance, an Alexanderson alternator with a 10,000-pole rotor spinning at 300,000 RPM would produce a transmission frequency of 50 MHz, into the lower portion of the VHF band), but the advances in technology required to allow a large rotor to be spun at the immensely high speeds necessary without suffering catastrophic failure did not occur until long after the Alexanderson alternator had become obsolete. The latter problem greatly complicated "listening through" (that is, stopping the transmission to listen for any answer). These were electrically "noisy"; the energy of the transmitter was spread over a wide frequency range, so they interfered with other transmissions and operated inefficiently. E. F. W. Alexanderson, U.S. Letter to Mr. Mayes from Lt. Thomson, Elihu (September 12, 1890). "letter".|Pretend you're Looking for a Folder