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BELL SYSTEM TECHNICAL JOURNAL 



part of that month. Initial production deliveries of these radars were made 

 in December I'Ul. 



Typical installations of the Mark 4 Antenna on the secondary battery 

 directors of a battleship are shown in Figs. 35 and 36. The main frame 

 installation for Mark 3 and Mark 4 on a battleship is shown in Fig. 37 



Fig. 37 — Radars Mark 3 & 4 — main units on Battleship New Jersey (Navy Photo 181809) 



while typical installations of the train and elevation operator's units in the 

 director are shown in Figs. 38 and 39. 



Application and Use of Mark 3 and 4 Radars 



The Mark 3 radars, designed for use against surface targets onl}', were 

 generally installed on the main batter}^ directors of battleships and cruisers. 

 The Mark 4 radars for use against either surface targets or aircraft were 

 generally installed on the secondary battery directors of battleships and 

 cruisers, and on the one and only dual purpose director on destroyers. 

 Thus a battleship usually had two Mark 3 and four Mark 4 equipments and 

 a destroyer one Mark 4. Practically every ship in the fleet, of destroyer 



