NGT—Checks and adjustments
194 NGT Transceiver System Technical Service Manual
Checking performance of the transmitter
Checking the transmit frequency
The transmit frequency is checked using the same method as frequency adjustment (see
page 173, Adjusting frequency).
Checking the ALC
To check the ALC:
1 Connect a signal generator to provide two-tone audio (700 Hz and 2300 Hz) via the
test unit to:
• the audio input on the 15-way GPIO connector on the junction box or 2012 RF
Unit (see Figure 40 on page 170), or
• the 2011 RF Unit via the NGT test handset (see Figure 41 on page 170)
1 Hold down PTT, then increase the audio output slowly until the moment when the
output power stops increasing.
This point is the ALC threshold.
1 Record the PEP output and increase the audio input by 10 dB.
The increase in output should be less than 0.5 dB above the ALC threshold.
If the increase in output is greater than 0.5 dB above the ALC threshold, further
analysis is required.
1 Release PTT.
NOTE
The transceiver must be in Service mode to perform these checks (see
page 154, Accessing Service mode).
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