A. General Description
1. General
The Model 300SA is a solid-state slave amplifier capable of driving up to ten watts of 312
ohm loudspeakers. Model 300SA is capable of amplifying voice or tone signals originating
at the SelecTone Command unit or other audio source. Refer to the service manual packed
with the SelecTone Command for additional information.
Electronic circuitry is located on a printed circuit board within the rugged diecast aluminum
housing. All connections (power, signal and speaker) can be conveniently made at one ter-
minal board within the housing. It is designed to operate from 24 volts AC or DC.
2. System Application
A typical system is shown in Figure 1. One Model 300VSC is capable of activating hun-
dreds of Model 300SA and Model 300GC units. Observe that Figure 1 illustrates that it is
possible to use Model 300GC units (when equipped with Model 300CK printed
circuit connector board) in combination with Model 300SA units.
B. Specifications
1. Model 300SA Slave Amplifier.
a. Operating Voltage
24 Vac or dc, ±10%
b. Standby Current
24 Vac – 10 mA, 24 Vdc – 5 mA
c. Operating Current
24 Vac – 1.50 A (max.),
24 Vdc – 0.83 A (max.)
d. Tone Signal Output (square wave)* 24 Vac – 21 Vrms,
24 Vdc – 19.5 Vrms
e. Voice Output (undistorted sine wave)*
24 Vac – 14 Vrms,
24 Vdc – 13.5 Vrms
f. Maximum Power Output*
24 Vac – 14.7 watts,
24 Vdc – 12.7 watts
g. Weight (Net)
2-3/4 lb (1.24 kg)
h. Dimensions (inches)
5-5/8 x 4-15/16 x 3-1/4
i. Temperature Range
-40 °C to ~75 °C
* Measured with 30-ohm resistive load
C. Installation
1. Unpacking
After unpacking the Model 300SA, examine it carefully for possible damage that may have
occurred in transit. If the equipment has been damaged, file a claim immediately with the
carrier stating the extent of damage. Carefully check all shipping labels and tags for special
instructions before removing or destroying them.
2. Mechanical Installation
The Model 300SA has been designed to be installed on any relatively flat surface. After
deciding upon the mounting location, proceed as follows:
a. Loosen the two screws that secure the cover to the housing. Gently pull the cover away
from the housing.
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