Troubleshooting
Apollo SL40 Field Maintenance Manual
13
TRANSMITTER
TRANSMITTER PERFORMANCE
The following specifications define expected transmitter performance.
Class 4
Output Power 8 watts minimum carrier at 12 VDC input.
6 watts minimum carrier at 10 VDC input.
The transmit is lock out below 9 VDC input
Frequency range 118.000 to 136.975 MHz, 750 channels
Frequency tolerance ±15 PPM from 20°C to + 70°C
Microphone input Two inputs, standard carbon or dynamic MIC with
integrated preamp providing minimum 70 mV rms into
1000Ω load.
Modulation capability 85% with 100 mV to 1000 mV rms microphone input at
1000 Hz.
Audio frequency distortion <10% at 85% modulation at 350 to 2500 Hz.
Audio frequency response <4dB variation with 350 to 2500 Hz, 85% modulation.
Carrier noise >35dB down
Sidetone output up to 280 mW into 100Ω, 120 mW into 500Ω.
Duty cycle 100%
Stuck Mic time-out 35 seconds, reverts to receive.
Transmit key Input pull low to enable transmitter
TRANSMITTER FREQUENCY ERROR
Transmitter Frequency error is measured using the HP 8920. This is accomplished by
presetting the SL40 to the same channel as the HP8920 and reading the frequency error
from the HP8920 Communications Test Set.
NOTE: Set the DC supply voltage to 13.75 volts ± 0.75 volts prior to
performance evaluating the transmitter.
Procedure:
1. Set the HP 8920 as listed below. Use Figure 3 and Figure 4 as guides.
Press PRESET
Press TX function
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