cooler operating temperatures than would otherwise be
channel. A portable microphone jack is also provided.
possible. Figure 7-27 is a blockdiagram of an amplifier.
This jack can be used for local testing of the system or
Switches, Timing Controls, and Indicators
Three toggle switches located on the front of the
The microphone control station inputs to the am-
control panel provide power to the amplifiers and the
plifiers are controlled by five 2-position toggle switches
located on the front of the control panel. In the ON
position, the microphone control stations are connected
A power available lamp and six blown-fuse indica-
to the amplifiers, and in the OFF position, they are
tors are also mounted on the front of the control panel.
ADDITIONAL SOUND EQUIPMENT
The outputs of the amplifiers are individually
Additional sound equipment used with the system
connected to the loudspeaker groups by five 3-position
consists of (1) microphone control stations and (2)
toggle switches located on the front of the control panel.
In the up position, the loudspeaker groups are connected
to channel A; and in the down position, they are
Microphone Control Stations
connected to channel B. Under normal operating
The microphone control stations located in the sonar
conditions, the switches should be positioned so that the
control room consist of both microphones and foot-
loudspeaker load is evenly divided between both
operated switches. A portable microphone and an
amplifier channels. When the switches are in the center
associated jackbox is provided for the sonar control area
position, the loudspeaker groups are disconnected from
supervisor, and a flexible microphone and foot-operated
the amplifier outputs. Separate connections provide for
switch is provided for each sonar operator's position.
local speakers located adjacent to the associated
The flexible microphones and foot-operated switches
microphone control stations, and muting features are
are wired in parallel to permit hands-free operation by
accomplished in the control rack.
the operators. The microphone inputs from the
An output test meter and two toggle switches,
operators' positions connect to the control panel relay
designated CHAN A and CHAN B, are provided on the
assembly in such a manner that only one microphone is
control panel for testing the output of each amplifier
connected to the amplifier input at a given time. This
Figure 7-27.--Block diagram of an amplifier.