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 Brandes 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.
By Cdr. E.J. Quinby, USN-RET
From the Society of Wireless Pioneers "Sparks Journal"
J. Donald Haig shares his thoughts from being an operator on various vessels back in the 1930-40's.
Spark Station Equipment