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Technical details

AERIAL SA101 Type 4249F

13 feet 6 inches long and 3 feet high
azimuth beam width of 0.5° and an elevation beam width of 3.8°

Elevation adjustable between 0° and 12°
Azimuth Speed - 10 RPM
35dB gain
9410 Mc/s
50 K.W. peak power
Pulse length 2 microseconds at a PRF of 333 pps
-100dBm Receiver Noise Level, Swept Gain Range - 60 NM
12" PPI
Ranges;25, 50, 100, 200 nm
Iso-Echo system
Automatic Camera fitted to PPI - pre determined time interval


"The radar had an Iso-echo system to allow assessment of rainfall rates out to 60 to 100 miles and assist in detection of hail".This unit was below the elevation unit and had two controls. On the left a 3 position multiplier switch labeled A-B-C and on the right a stepped attenuator switch with nine positions, each step was about 1.5db. This Iso-echo system and the Swept Gain (out to 100NM) was not originally supplied with the radars but added in 1963 (1) (2) (3)

SNW51 Transmitter Type 1454M
Trigertron without cover

The receiver had a 30MHz IF that was stagger tuned over 8 stages with both main and swept gain control.


The Transmitter used a trigertron in the modulator which after 2 to 3 months continuous use had to be replaced due to the amount of scale accumulated inside the envelope and of course it wasn't operating properly.(1) This tube was normally covered with a protective 'sock' in case it exploded.









SNW51 Display Type SD701 at Sydney (1964)
SNW51 Display Type SD701 at Byron Bay
Antenna Type 4249F being installed at Saddle mtn.

The analogue meter that indicated the elevation angle was mounted on the left of the PPI, this was wall mounted at Byron bay .

The iso-echo unit can be seen mounted under the Elevation meter in the photo of the Sydney RFC Display Unit.











The antenna was 13 feet 6 inches long and 3 feet high giving an azimuth beam width of 0.5 degree and an elevation beam width of 3.8 degrees. The feed was a slotted waveguide section providing a horizontally polarised beam. The antenna could be tilted up to 12° in elevation. The elevation actuator was a Bendix Aircraft Flap Motor which gave excellent control.

There was a spare anttena with turning gear kept out on the grass at the Observatory Hill Workshop in Sydney. Every two years it would be totally overhauled, including sandblasting and repainting. it was then trucked up to Byron Bay and swapped with the unit in service. Vidya recalls travellingg on board the truck with trvor Donald during his time working in N.S.W. (1975-1980)(4)


(1) Trevor Donald (private communication)
(2) Weather News(#84 & 194)
(3) Working Paper No 48 June 1962, Notes on Sferics, Radar and Atmospheric Turbulence by Goodman, Bath & McRae
(4) Vidya Sharma (private communication)