The Muirhead K470 facsimile transmitter was placed at radar sites to transmit facsimiles of the radar echoes to a forecasting centre.
In 1975, the fax. was used to send "Chinagraph" pencil sketches of
the echoes on the PPI were made on a transparent plastic sheet. Reg Carter tells
how the Chinagraph used to rub off the sheet onto the blind of the fax transmitter,
which would become mid-brown colour and this gave a dark background to all the
received pictures. He recalls after cyclone Tracy in Darwin, he tried to clean
the blind but the "muck" was so ingrained it wouldn't budge.
At Learmonth(W.A.) and Mt Kanighan(Qld), the K470 was also used to send photos of the echoes on the PPI to the Tropic Cyclone Warning Centres at Brisbane or Perth. The facimile was received on a Muirhead K150 Receiver which would reproduce the transmitted image at twice the original size. These photos were taken of by a conventional camera of the PPI or by a Polaroid camera fitted to the Photo PPI unit.
Darwin's K470 in the late 70's
The fax line ran between the radar and the WSO building in an underground steel duct. Invariably on weekends during the wet season the Tech would be called out because no faxes were been received. Dave Shaw tells of always going out on those calls with a spare K470 output transistor in his pocket. The lightning strike would have destroyed that component and as it was socketed it was an easy repair. The irony was that the fax was used only when the storms were in the area, which was the cause of the transistor failure.
In 1976 a remote PPI was installed in the Darwin RFC and thus the fax service to there was discontinued.