285P RADAR OFFICE


285P Office. Starboard bulkhead.

285 transmitter; supply board for outfit DPA (50 volt, 50 cycle, 3 phase); At very rightmost, a valve heating box for CV-13.

RCN Photo HS 1749-71

Type 285 was a secondary-battery gunnery radar, first built in 1940 and then fitted in 1941. It employed two types of aerials; one with 6 Yagi's and the other with 5 Yagi's. In the six Yagi version, three aerials were used to transmit and three to receive. This arrangement produced a narrower 18 by 43 degree beam. Bearing accuracy was 3 to 4 degrees typical, with an accuracy of 100 yards on the 15,000 yard scale. This 25 kilowatt set was keyed by 1.7 microsecond pulses and operated at a 50 cm wavelength. At maximum range, it could detect a cruiser at 7 nm. On HAIDA, the 285 set was fitted-on-build (1943).


285P Office. Starboard bulkhead.

Power board for outfit DPA; valve heating box. (Can anyone confirm that this was a pre-heater for mercury vapour rectifiers?)

After bulkhead. Power supply board and motor starter for outfit DUA (180 volt, 500 cycle).

RCN Photo HS 1749-72












285P Office. After bulkhead.

285 receiver.

RCN Photo HS 1749-73


















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