120 



USRL TEST STATIONS 



Figure 55. Electrical equipment of high-power system. 



ing machinery of this size in order to realize the point 

 of greatest stability. 



The Mountain Lakes amplifier operates at 220 

 volts directly off the single-phase, 60-cycle supply. It 

 differs from the Orlando unit in that all grid-supply 

 voltages are regulated quite closely since the grid 

 currents may rise to 20 or 30 milliamperes in the final 

 power stage. 



The amplifier at Mountain Lakes is shown in Fig- 

 ure 55. The bay appearing at the side is used for ter- 

 minating crossties to the other systems and for con- 

 nections to the amplifier. In this bay are also a master 

 intercommunication station, attenuators, and a sepa- 



rate signal source (Western Electric Company 17B 

 oscillator). Plans are being considered to incorporate 

 in this bay a generator and transmitter modulator 

 with longer pulses than are now available. This 

 pulsing equipment would be used with the power 

 amplifier to simulate actual operating conditions in 

 echo-ranging systems. The arrangement would allow 

 projector characteristics to be measured under typi- 

 cal working conditions. This is of particular impor- 

 tance in the study of cavitation and of heating due to 

 power losses on the transmitting efficiency. 



6.2.6 



High-Pressure System 



Measurements on transducers operating in the in- 

 termediate-frequency range and under hydrostatic 

 pressure up to 300 lb per sq in. may be made in the 

 high-pressure tank. The pulse system is used to over- 

 come the difficulties of testing in a confined medium 

 but there are still limitations as to what can be tested 

 in the tank. 



Description of High-Pressure Tank. 



The tank, made of l% 2 -inch firebox steel, is a 

 horizontal cylinder 8 feet in diameter and 14 feet 

 long. There are eight glass-covered viewing ports 

 along the sides of the tank. Two ports on top provide 

 access to the interior. One port is oval in shape, being 

 1 foot wide and 3 feet long. It is provided with a 2y 2 - 

 inch thick steel cover. The other port is circular and 

 has a diameter of 2 feet. Built as an integral part of 

 the cover of this port is a single shaft rotator, similar 

 to the rotator described in connection with the inter- 

 mediate system. This rotator can be used in conjunc- 

 tion with the polar recorder turntables of either 

 intermediate-frequency system. The shaft of the 

 rotator passes through a pressure gland in the center 

 of the cover. The circular port is located 4y 2 feet 

 from one end of the tank and the oval part is located 

 3y 2 feet from the other end. Baffles of 1-inch steel 

 plate have been placed at the center of the tank as 

 shown in Figure 61, leaving a square aperture 3 feet 

 by 3 feet. An overhead monorail and hoist system is 

 used to handle the heavy port covers and test instru- 

 ments. 



Rails for a carriage from which to suspend trans- 

 ducers are mounted in the tank under the oval port. 

 The carriage is controlled by two threaded rods that 

 pass through stuffing boxes in the end of the tank and 

 terminate in hand cranks. One rod moves the car- 



