Array:

Mounted some 190 feet above the ocean surface which provided its electrical twin, the Titanic's aerial array provided a conspicuous display of her technical sophistication.The elements were bare silicon bronze wires with feed lines connected to their centers.The configuration is known as "Twin T" because they were driven in pairs to provide gain.Signal strength to the sides was enhanced by overlaying the radiation patterns of two parallel elements.Radio coverage in the fore and aft direction was correspondingly reduced.

Each element of a Marconi aerial is cut to one quarter wavelength.At Titanic's usual frequency of 600 meters, this yielded a length of about 450 feet from the front spreader bar.A high tension insulator on either end provided electrical isolation from the rest of the rigging.On one end was a strong, weatherproofed,elastic cord to absorb shock and prevent damage to the aerial.From over the fourth funnel a suspension cable connected to each element and ran to the rear spreader bar to make up the 600 feet total distance between masts.The ash spreader bars that carried the rig were equipped with hoists and guy lines much like the yards of earlier square rigged ships.Her 30 foot spreaders provided a 9 foot spacing between elements.

Pillar:

The four feed lines were grouped together on an insulated lead-in stay which ran to a bullseye and anchor on the radio room roof.This took the stress of the aerial's movement high overhead.An insulated lead-in from each of the two Twin-Ts tapped off from the stay and entered the pillar about 6 feet above deck.The leads passed through the roof inside the pillar (conduit).Its height and the Bradfield insulators on top served two functions:

1.Minimize leakage.Radio Frequency (RF) energy travels mostly on the surface of a conductor ("skin effect").The insulator discs were there to present the maximum non conducting surface path possible to ground, thus minimizing leakage of RF signal.A cone on top of the pillar deflected spray and precipitation from the discs as a wet surface is a much better conductor.

2.Maximize safety.The spark gap transmitter impressed very high voltages on the aerial leads.Easily lethal to someone grounded on deck coming in contact with them."

Emergency Set:

In addition to the 5 kW main transmitter and magnetic detector, there was a 1 1/2 kW emergency transmitter with its own receiver.Likewise, there was an emergency aerial coiled and stored below decks for erection and use in the event of catastrophic loss of the main array.

Radio Shack:

The "Marconi room" was situated on the boat deck (i.e.: the same deck as the bridge), at the after end of the superstructure containing the bridge and officer's accommodation - it was about 40 feet aft from the bridge, connected via the corridor which ran down the port side of the officer's quarters.The room was in the center of the accommodation - it did not have an outside facing porthole. Natural light was provided via a skylight in the deckhead (ceiling).The motor-generator and rotary disc transmitter were housed in a special, shielded, "silent" room next door to the radio room to reduce interference to the main receiver. During commissioning tests Phillips and Bride exchanged messages with coast stations at Tenerife (2000 miles away) and even Port Said (more than 3000 miles distant).

The MARCONIGRAPH:

The following material is excerpted from the May 1912 edition of The MARCONIGRAPH provided through the courtesy of Louise Weymouth, Company Archivist, Marconi plc:

"The wireless equipment of the "Titanic" was the most powerful possessed by any vessel of the mercantile marine, and only equaled by that of the "Olympic".Its generating plant consisted of a 5 kW motor-generator set, yielding current at 300 volts 60 cycles.The motor of the set was fed at 110 volts DC from the ships lighting circuit, normally supplied from steam-drives sets"

"To eliminate as far as possible the spark-gap and its consequent resistance, which, as is well known, is the principle cause of the damping of the waves in the transmitting circuit, the ordinary Marconi rotary disc discharger was used."

"The guaranteed working range of the equipment was 250 miles under any atmospheric conditions, but actually communications could be kept up to about 400 miles, while at night the range was often increased to about 2,000 miles.The aerial was supported by two masts, 200 ft. high, stepped 600 ft. apart, and had a mean height of 170 ft.It was of the Twin-T type and was used for the double purpose of transmitting and receiving.The earth connection was made by insulated cable to convenient points on the hull of the vessel."

"The receiver was the Marconi standard magnetic travelling band used in conjunction with their multiple tuner, providing for the reception of all waves between 100 and 2,500 metres."

"By reason of its robust nature the magnetic detector could be employed permanently connected to the transmitting aerial, thus dispensing with all the mechanical change over switching arrangements."

Auxiliary Generating Sets:

To supply power when the main plant was off-line there were two 30 kilowatt engines and dynamos situated on a platform in the turbine engine room casing on Saloon deck (D) level, 20 ft. above the waterline.There was a also an independent storage battery and coil to supply power to the wireless set in the event of total failure of the current supply from the ship's dynamos.

Operational Background:

In 1912 radio at sea was only just past the novelty stage.Of 23,217 registered powered ships, about 1,000 (400 of them British) were fitted with radio and these were mostly ships on the busy North Atlantic. Californian's radio was fitted as late as January, 1912.All used spark transmitters, which were very wasteful of power.Titanic's Marconi set used 5 kW, of which only about 500 watts actually reached the aerial. The normal wavelength was 600 meters. On Marconi ships the time of each message was recorded in GMT, when east of 40° W and in New York time when to the west. The radio operators were responsible for maintaining clocks showing these times.Photos of the Titanic and Olympic radio rooms show these two clocks mounted on the bulkhead.

At the time of the disaster some of the strongest signals on the air were from installations belonging to private clubs and individuals.Although initially blamed for interfering with emergency traffic, on the evening after the sinking all the amateurs in the New York area voluntarily stayed off the air.They spent that night copying the intermittent signal of the cruiser Salem near the scene of the sinking trying to report the names of the survivors.Through their efforts, and the Newport Naval Base, it was possible the next day for newspapers to publish a full list of the survivors of the Titanic disaster.

Author:

I'm an Electrical Engineer by training and trade and proud to credit Amateur Radio for most of my radio savvy.Ham operators have been at the forefront of technical experimentation and emergency preparedness from the very beginning.

For More Information:

THE RMS TITANIC RADIO PAGE - http://www2.dynamite.com.au/rmstitanic/

How to Become An Antenna Guru - http://www.borg.com/~warrend/guru.html

The Radio Legacy of the R.M.S. Titanic - http://avsia.com/djohnson/titanic.html

MARCONI CALLING - http://www.marconicalling.com/

Bright "Sparks". The "Wireless Telegraphists" and Their Work. - http://www.users.senet.com.au/~gittins/radio.html

BoT "Report on the Loss of the 'Titanic' (s.s)" (Mersey Report)

http://www.titanicinquiry.org/BOTReport/BotRep.htm

Larry Jibson

Titanic Research & Modeling Association