I've been reading about the history of telegraphy, and I knew that back then radio signals were produced in massive strength by using powerful dynamos and magnetos, with a telegraph key to interrupt this current, as described in Tom Swift and his Wireless Message, by Victor Appleton. I first read that book in eighth grade, and since then my fascination with radio grew.
I know that lots of technological advancements have been made since, which doesn't require as much energy to produce radio signals, especially when there are repeaters to carry on the signal.
Now, I'm wondering why a continuous wave will cause the transceiver to emit a 750 Hz tone in accordance to the signal's interruption. Wouldn't it sound like white noise, or mains hum, whose alternating frequency is 60 Hz, or a harmonic above that, 120 Hz? Of course, with the latter example, one would have to actually be connected to a power source. I also wondered what the mayday call sounded like on the Titanic, and it sounded like this.