Spark Transmitters were widely used in ships during the early 1900's. This set was installed on the S.S. 'Burwah', a merchant ship of Australian registry. The photo on the right shows the radio room of the S.S. Burwah, with the set installed. AWA was formed in 1913 and is still in existence today.

Below are the individual components of the radio set:

 
AWA P1 Wireless Receiver

The AWA Model P1 was a single tube regenerative receiver. The original tube was an Australian made "Expanse B", similar in appearance to a Deforest Tubular Audion. If you look closely at the photo above, you can see the tube on the front of the receiver. The set was later retrofitted with a more "modern" O1A detector which was installed on the back panel. The P1 was the set used to receive the first direct wireless transmission from London to Australia, on a wavelength of 25KM (12KHz) - well inside the audio band!

The heart of any spark transmitter is the spark coil - The AWA coil includes an integrated gap (it is the rectangular metal object mounted on the top front, just above the interrupter. This gap is a known as a "plain discharger" because it is fixed and has no rotating wheel.

Spark Gap and Coil

"Jigger"
Helical Transformer

The output of the induction coil was fed to the "Jigger" or helical high-voltage tuning transformer (left). The jigger output was used to drive the transmitting aerial.

 

High Voltage Condenser