Figure 4-17.-Hydrophone and projector.
indicate the sonar dome azimuth deviation from
magnetic north. The pressure potentiometer provides
an output to indicate depth of the dome in water. The
projector is covered with a black neoprene boot that is
filled with oil.
The hydrophone assembly consists of 16 stave
assemblies bolted to a cork-lined fiber glass barrel, an
end bell, a temperature sensor, and an electronic
package. The staves, filled with oil and hermetically
sealed, convert the received acoustic pulses to
low-level ac signals. These signals are amplified and
applied through the special purpose electrical cable to
the receiver located in the helicopter. The stave
housings are stainless steel, each containing 12
matched ceramic rings with trimming capacitors, and
they are mounted on a printed-circuit board. The
output of each stave is applied to a preamplifier,
which is on the electronics package. A temperature
sensor for measuring temperature of the water is
located on the end bell.
The dome requires no adjustments. All inputs and
outputs are made through the special electrical
connector on top of the electronic housing.
Sonar Receiver
The sonar receiver (fig. 4-18) consists of all
electronic circuits required for the processing of input
signals of the sonar set.
The following switches and indicators are
mounted on the front panel of the receiver:
1. A RANGE SCALE-KYDS switch for
selecting the desired operating range.
2. A MODE switch for selecting the operating
mode of the sonar.
3. A FREQUENCY switch for selecting the
desired frequency.
Figure 4-18.-Sonar receiver.
4. A dual CURSOR POSITION control for
controlling the cursor circle on the CRT in both
azimuth and range.
5. A three-digit BEARING display that indicates
cursor circle bearing in degrees from magnetic north.
6. A five-digit RANGE-YARDS display that
indicates the range of the cursor circle in yards.
7. An AUDIO switch/indicator for selecting
audio from all eight sectors, or only the sector
selected by the cursor circle position.
8. A TARGET switch/indicator for applying
bearing and range information to the pilot’s bearing
and range indicator.
Sonar Transmitter
The transmitter (fig. 4-19) develops the signals to
be transmitted by the system. A POWER circuit
breaker, located on the front cover of the transmitter,
Figure 4-19.-Sonar transmitter.
4-13
