RA7915 Fixed Frequency Receiver

General Description

These receivers, which were built by Racal in Sydney, were used extensively by OTC in the coastal radio network. Both the single channel (above) and 6 channel (below) versions were used and some are still in service.

The museum's receiver became intermittent and was removed from service at La Perouse (Sydney Radio) on 8/12/98. It was the main 500 kHz Solas (Safety of Life at Sea) receiver and had spent many years monitoring distress calls in the South Pacific. It just didn't quite make the end of the Solas service on 500 kHz, which ended on 31/1/99.

Technical Data

The RA7915 is a fixed frequency crystal locked receiver operating in the frequency range 0.04-30 MHz. There is a single channel and a 6 channel model.

Operation is possible on AM,CW, USB and SSB, crystal filters being optional for each mode.

The receiver is all solid state and consists of 4 units. The mainframe contains the power supply (240vac) and input/output lines. An internal speaker is fitted. Extensive remote control provision has also been made.

The preselector board is an RF stage utilizing a band pass filter. Up to six of these filters may be fitted, depending on the number of channels required.

The oven module contains up to 6 channel crystals plus a 10.7 MHz carrier crystal. (The set is single conversion, 10.7 MHz I.F.)

The Receiver Board is by far the most complicated. It contains the mixer and all the remaining signal processing, including the crystal lattice filters, IF amps and audio stages. The BFO is adjustable over the range plus/minus 500 cps.

Illustrations of the set