5271 HYDROGRAPHIC MANUAL PaGE 496 



5271. Recorder Cabinet 



The fathogram may be viewed through a removable glass panel on the front of 

 the recorder cabinet. Gain controls, phasing dials, meters, and other controls are 

 located on the front, and additional controls are located on both the left and right side 

 of this cabinet. The principal parts of the recording device and their functions may 

 be described briefly as follows: A starch-iodide paper is used for recording, which is 

 previously dampened by passing over a wick. A stylus passes back and forth across 

 the paper with a linear motion, being in contact with the paper only when moving 

 from left to right, when it is in position for recording. The paper has no printed 

 scale, but passes under a metal scale that is graduated from to 142 fathoms. The 

 electric current from the echo amplifier, caused by the reception of the transmitted and 

 echo signals, flows from the stylus through the paper to a metal platen over which the 

 paper is passing, resulting in dark stains on the paper at such points. The paper 

 moves vertically downward imder the stylus at a constant rate, fed by rollers driven 

 by an electric motor. A d-c motor, whose speed is governor-controlled, furnishes the 

 power to operate the stylus, move the paper, and operate the various keying cams. 



The keying mechanism can be operated in 11 additional positions, or phases, to 

 advance the keying by steps of 100 fathoms, thus making it possible to record any 

 depth between and 1200 fathoms at the original enlarged scale. For example, for 

 sounding in depths of 450 fathoms, the phasing control should be on position 4. This 

 will advance the keying so that it occurs at a time equivalent to 400 fathoms in depth 

 before the stylus reaches the zero of the fathogram, and when the stylus reaches the 

 equivalent of 50 fathoms on the paper, the echo arrives and is recorded. 



In normal operation one signal is transmitted for each cycle of the stylus, or one 

 signal in approximately 1 second; however, by a switching device it may be operated 

 so that a signal is transmitted at only every third cycle of the stylus, or one signal in 

 approximately 3 seconds. (See also 5555.) Wlien one signal per second is transmitted 

 it should be noted that an echo trace will be recorded at intervals of 400 fathoms and 

 on three different phases of the instrument; for example, if the actual depth is 150 

 fathoms, a record will be made at 150 and also at approximately 550 and 950 fathoms. 

 Therefore, if the instrument is started in deep water it is essential to operate it first so 

 that it transmits only one signal each 3 seconds until the correct phase has been deter- 

 mined. With one transmitted signal per second there will also be a band of interference 

 at multiples of approximately 400 fathoms, where the echo of a preceding signal and a 

 transmitted signal record at approximately the same place on the fathogram. 



Other controls and mechanism in the recorder automatically mark a continuous 

 reference line near the left edge of the paper to represent the zero of the scale, and make 

 a time reference mark once a minute on the fathogram. The following are also pro- 

 vided: a fix-marker button to make a reference mark across the record at any desired 

 time, an electric pencil for recording notes on the fathogram, and a connection to the 

 ship's log for recording the ship's run on the record. (See also 5544.) 



5272. Contactor Box 



The principal function of the contactor box is to furnish the necessary energy to 

 operate the magnetostrictive transmitting unit. A 4-microfarad condenser is charged 

 to 1,000 volts by means of an induction coil, from power furnished by the ship's 110-volt 

 direct current. A relay, operated from the keying cam in the recorder cabinet, dis- 

 charges this condenser into the magnetostrictive transmitting unit. 



