Marconi 1 kW Ship Station from around 1915
By--CDR. E.J. Quinby, USN-RET
From the Society of Wireless Pioneers "Sparks Journal"
A few suggestions from the recesses of this writer's dim memory are
offered as a starter. On the slate switchboard is the typical United Wireless Telegraph
Company's layout, inherited by the Marconi Company in the infringement settlement
which drove the U.W.T. Co. into bankruptcy. The goose-neck lamp at the top illuminates
the volt-meter (left)and the ammeter (right) showing the voltage of the ship's D.C.
supply and alternating current being drawn from the Crocker-Wheeler motor-generator set
below. The cartridge fuses beneath these two switches are missing. Between them is the
starting-box for the M/G set with handle shown in the off position. It is spring-loaded
so that the handle will fly over to the off position when current to the electro-magnet
is interrupted. At the upper center is shown the United Wireless Type D Tuner, with
single=-slide and double slide tuning coils and crystal detector and a pair of 2000 ohm
Brandies headphones, if a cheaper set has not been surreptitiously substituted by some
unprincipled boomer Operator. Beneath that is the United Wireless triple-pole
Send-Receive Transfer Switch, to which has been add a short-circuiting bridge, supported
by the two long knife-blades.
In the UP position, this switch connects the Type D Tuner to the antenna and disconnects the keying circuit, and in the DOWN position the short middle blade grounds the Type D Tuner, and the "bridge" added in the modification connects the Antenna Loading Coil of the transmitter to the Antenna.
Beneath the key is the typical United Wireless "coffin" transformer, across the
output of which is connected the bank of U.W.T. Leyden Jars which will produce the
artistic violet rays and the fragrant ozone, while the Marconi non-synchronous Rotary
Spark gap illuminates the immediate vicinity with brilliant blue-white flashes and
produces the crashing, cracking sounds effects to summon the curious male passengers and
panic the timid souls among the fair sex. Its two semi-circular segments support the
stator electrodes connected in series between the Leyden Jar bank and the primary of the
Oscillation Transformer. Revolving between the two segments, the rotor is insulated from
the motor shaft. The secondary of the Oscillation Transformer is connected in series
between the Antenna Loading Inductance and the square unit connected in the ground lead
at the right. Bless my stars and garters,--That MUST be the legendary Marconi Jigger!
Some of the Old Timers will probably recall playing with the switch feeding power to the Rotary Gap Motor, to put a little "Musical English" into the pitch of their dots and dashes,--on a rising scale at the start of transmission, and a descending scale at the finish. Some will recall how they shot their Transmitter Condensers by letting the rotary gap speed fall too far before terminating the transmission. A resultant sudden SNAP and cessation of the sparks meant that the condenser had developed some cracked plates. That emergency meant a messy job of dismantling and repairs if your ship was equipped with the "new" Marconi oil-immersed glass plate condensers. Thus, in our innocence, we learned a few things NOT to do.