Според
http://hf.ro/ :
The Titanic's "wireless" equipment was the most powerful in use at the time. The main transmitter was a rotary spark design, powered by a 5 kW motor alternator, fed from the ship's lighting circuit.
The equipment operated into a 4 wire antenna suspended between the ship's 2 masts, some 250 feet above the sea. There was also a battery powered emergency transmitter.
The main transmitter was housed in a special room, known as the "Silent Room". This room was located next door to the operating room, and specially insulated to reduce interference to the main receiver.
The equipment's guaranteed working range was 250 miles, but communications could be maintained for up to 400 miles during daylight and up to 2000 miles at night.