The genesis of the 284 began in mid 1939 when the Admiralty fired almost everybody responsible for radar R&D at the ASE (Admiralty Signals Establishment). Progress from 1937 had been nill. A young self taught engineer F Coales attached to the ASE was placed in charge of the 60cm project. The Admiralty had planned on three radars being developed; of 4 meters wavelength, 150 cm wavelength, and 60cm wavelength. The 60cm project was to be specific for gunlaying. Coales turned to the private firm of GEC and basically subcontracted GEC's scientists and engineers- guided by Coales himself. Coales later said of himself he had a vision but does not "read math". He demanded that the GEC people put everything in laymens terms. The design GEC came up with was the basis of all the 50cm gunlaying radars, the wave length having been changed from 60cm.
Actually the wave length was 51.5 cm. The basic 50cm design was used for the 283, and 285 radars as well. These other designs were for the flak batteries and differed in their antenna designs. The 284 radar consisted of one of two possible antenna designs mounted to the fire control directors. This consisted of the one already alluded to, known as the "Pig Trough", which consisted of individual 1/2 wave dipoles arrayed end to end within a three sided box reflector to eliminate any back leakage. The other possible antenna was the Fishbones usually associated with the Type 285 flak and secondary battery radar. The Fishbones was two Yagi antennas, which resemble VHF TV antennas which used to be ontop of houses all over- if your old enough.
(the following is for the early model 284)The transmitter was a push pull amplifier consisting of two GEC Micro-Pup transmitter triodes. Power output was about 25kw at the transmitter but about 12kw from the antenna (British power output was measured at the transmitter instead of at the antenna per German and US practice). The receiver was a unique super het design in that it used anode modulated mixer Pentodes (a type of vacuum tube). Usually, with vacuum tubes the signal is applied to the grids, but in this case GEC tied the grids to ground. This minimized inherent noises of pentodes and made for an acceptable signal to noise ratio at 600mhz (50cm) while simultaeously having a large bandwidth mismatch. Because of the unique anode modulation of the receiver and the transmitter tubes the 50cm radars required extended warmup times of up to 45 minutes before they could be used. They also required being shut down and rested after a few hours of constant operation.
Instrumentation was by a single A-scope only and therefore completely abstract. The A-scope measured only range with the pulse ocurring at the zero point along a linear time base. The echo pulse return was a deflection or kink in the trace which occured at the appropraiate place along the time base. By converting the comparitive distance between the zero point and the "pip" on the time base to range; range to target was measured. Range accuracy was nominally 240 yards.
The resolution for range was 300 meters because of the 2 micro sencond pulse width.
The bearing which the antenna was aimed to could be determined to a finer degree of accuracy by determining at what bearing the signal provided the greatest pip amplitude. This method was known as max signal, and was accurate to 3/4 of a degree.
In tests of the first production 284 installed on the battleship King George V in Dec 1940 set the reliable ranges as follows:
14,00 yards to a destroyer
20,000 yards to a cruiser
It was not tested to another battleship, but the Suffolk's 284 was able to detect and track the Bismarck to a max range 26,000 yards. KGV's 284 first detected Bismarck at about 25,000 yards.
Entering a night sea battle is an awesome business.The enveloping darkness, hiding the enemy's.. seems a living thing, malignant and oppressive.Swishing water at the bow and stern mark an inexorable advance toward an unknown destiny.