Before revision: 45 kHz (first commercial superheterodyne receiver: RCA Radiola AR-812 of 1923/1924) 110 kHz was used in European AM longwave broadcast receivers.
After revision: down to c. 20 kHz, 30 kHz (A. L. M. Sowerby and H. B. Dent),, c. 50 kHz, c. 100 kHz, c. 120 kHz45 kHz (first commercial superheterodyne receiver: RCA Radiola AR-812 of 1923/1924) 110 kHz was used in European AM longwave broadcast receivers.