Camera Timer Unit

PPI Camers were controlled by the Radar Camera Timer unit, which monitored the radar's north marker switch to initiate an exposure at a selected interval.

The timer unit allowed the camera to be operated manually, automatically every second revolution of the antenna or automatically by the antenna contacts at a pre-selected time interval as determined by the setting of the Time Delay dial on the Timer unit. Alternative time delay clocks could be fitted to allow intervals 0.5 - 13 Min or 2.5 - 65 Min

Photographs could also be taken manually by pressing the cable remoted hand-switch which plugged into the front of the unit.(1)
Cameras used were either a Polaroid or a 35mm - Berning Robot 24M and Siemens 35mm cameras were used, the later introduced in 1970. Also a Bolex 16mm movie camera was used

The camera was manually aligned with the PPI. Sometimes they were mounted quite some distance away, across the room on a post. The Pt Hedland unit was mounted just inside the blackout curtain and many walked straight into the pole hidden behind the curtain!

The units were in use through to at least 1977.

Radar Camera Timer unit were installed at 277 and WF44 radar stations:
Darwin
Broome
Pt Hedland
Perth
Brisbane
Gladstone
Mackay
Townsville
(Pt Moresby)

References
(1) Radar Camera Timer Unit Handbook - EH150