John Flynn was planning his Australian Inland Mission Aerial Medical Service for remote communities and from 1926 Traeger worked for him, at £500 a year, on Northern Territory radio experiments.
After an outback tour of duty, Traeger began work in Adelaide on a transceiver for the flying doctor network.
The sets had to be cheap, durable, small and easy to operate. Using bicycle pedals to drive the generator, he found that a person could comfortably achieve 20 watts at a pressure of about 300 volts.
He enclosed the generator’s fly-wheel and gears in cylindrical metal housing, with pedals outside and a cast base to be screwed on to the floor beneath a table.
Traeger built the transceiver into a box, employing a master switch to separate the crystal controller transmitter from the receiver.
His famous pedal wireless was actually a pedal-operated generator which provided power for a transceiver.
Traeger’s time was divided between his workshop and the field where he taught radio operating and Morse code; despite the heat, he wore a dark suit and braces.
Once the first pedal sets had been introduced in Queensland in 1929, the invention created a communications revolution by diminishing the loneliness of the inland world.
In 1933 Alf invented a typewriter Morse keyboard, an accessory to the pedal sets which was widely used until the advent of radio telephony.
In 1939 Traeger’s set dispensed with pedals and adopted a vibrator unit. Emergency call systems linked inlanders with hospitals, and sets were used by the School of the Air, doctors, ambulances, councils, taxis, airways and ships.