Specifications

3
Specifications
Specifications
FIGURE 1. SPK300L Block Diagram
Audio Line
Voltage
1 volt, peak (0 dBm voltage-equivalent)
Average
Speech Level
Range
-20 dBV to -10 dBV
Absolute
Maximum
Speech Level
3 volts, peak (linear limit)
Audio Line
Impedance,
Nominal
200 50 ohms, 75 Hz to 20 kHz
System will continue to operate from 50 ohms to 300
ohms.
SYSTEM DC CURRENT
Nominal 32 volts DC
Operational
Range
18 to 35 volts DC
Steady state
without
damage
-1.5 volts to 36 volts DC
Transient 200 volts, 8 milliseconds or less (after this time, power
supply and user station fuses will open).
System DC
Current
Quiescent
(per station)
10 to 40 milliamps
Dynamic (per
station)
50 milliamps (w/25 ohm headphones)
70 milliamps (w/25 ohm headphones and lights)
100 milliamps (w/8 ohm speaker)
Start-Up
Current
1.25 amperes, 50 units, all kinds
Fault Current 4.0 amperes, power supply at voltage >12 volts
1.0 amperes, power supply at voltage <12 volts
OPERATING DISTANCES
Maximum DC
limit
5,000 ft distance along cable, power supply to single
station #22 gauge wire - DC voltage drop limitation.
Maximum AC
limit
10,000 ft. dry pair, power supply at each end, #22 gauge
wire
System
Capacitance
0.3 microgarads (cumulative effect of 10,000 ft. of
maximum cable at 30 picofarads/foot)
USER STATIONS SPECIFICATIONS
Input DC
voltage
20 to 35 volts DC, operating from -200 to +36 volts DC
without damage.
DC Current Quiescent, 10 to 40 milliamps
50 milliamps, typical (w/25 ohms headphones)
75 milliamps, typical (w/25 ohms headphones + lights)
100 milliamps, typical (w/8 ohm speaker)
Impedance
Across Line
10,000 ohms typical; 2,000 ohms worst case dynamic
operation
Ambient
Temperature
Range
Operating 0° C to 60° C (0° F to 140° F)
Storage -55° C to 125° C (-67° F to 257° F)
Noise
Contribution
to 200 ohm
Line
One unit: -75 dBu
Ten unit: -67 dBu
MICROPHONE PREAMPLIFIER
Imput
Impedance *
470 ohms
Source
Impedance*
200 ohms, nominal
Maximum
Input Level
150 millivolts
Voltage Gain 54 dB
Frequency
Response
100 Hz to 10,000 Hz, 3 dB