"In 1935 and 1939 W4OK was assigned to F.G. Carroll from Lake Worth, Florida and West Palm Beach, Florida respectively. ...
"I don't recall the radios used to receive these post loss messages, but I've restored some commercial home consoles from that era. While their dials are not very accurate as to frequency received, some were decent shortwave receivers. Considering that 1937 was about the height of that solar cycle for radio propagation and that the transmitter was right adjacent to salt water (a great reflector), it's certainly possible that these signals were heard in the US and elsewhere.
"You can see a graph of past solar cycles here. Look for the "Monthly Sunspot Numbers 1900-1999" graph. The higher the sunspot number, the better for radio wave propagation" (Brookner, Forum, 2010-12-22).