12-4. SPEAKER AMPLIFIER SECTION. Continued
Figure 12-5. Speaker Amplifier Section Module Locations
The speaker amplifier module contains the audio amplifier used to drive an external speaker. The audio input is
taken from the VOL switch. An internal switch is used to disable the amplifier when the RCU is transmitting, when
WHSP mode is being used, and when the RCU is receiving digital data.
The speaker amplifier module contains a series pass regulator which regulates the 6.75 V dc output from the
power supply down to 5.7 V dc. This voltage is called primary black power and is used to power logic circuits in
the black section of the RCU. Table 12-2 lists the destinations of this supply voltage.
Table 12-2. Primary Black Power Destinations
Primary Black Power
5.7 V dc
19A2-33, 19A4-19, 19A5-Q,
19A7-47, 19A7-49, 19A10-71,
19A10-76, 19A11-14, 19A13J1-K,
The DC power filter shunt regulates 13 V dc from the SPKR switch for use by the speaker amplifier module. It also
provides a 6.5 V dc reference voltage for the speaker amplifier module. The amplified audio from the speaker
amplifier module is input to the DC power filter and is transformer coupled out to the SPKR connector.