NGT—Checks and adjustments
170 NGT Transceiver System Technical Service Manual
Adjusting the exciter output level
To adjust the exciter output level:
1 Unplug the coaxial cable between the PA PCB and RF/IF PCB in the RF unit.
1 Connect a 47 Ω resistor from the Tx test point to ground on the RF/IF PCB.
1 Connect an oscilloscope to the Tx test point.
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), or
• the 2011 RF Unit via the NGT test handset (see Figure 41)
Figure 40: Setup for test unit with a 2010/2012 RF Unit
Figure 41: Setup for test unit and NGT test handset with a 2011 RF Unit
1 Select test channel 16 with USB mode.
1 Hold down PTT, then adjust the level of the two tones for compression.
1 Adjust the Y sensitivity of the oscilloscope for on-screen display, and adjust the
trigger for a stationary waveform.
1 Adjust the two-tone balance control for good crossover display.
1 Adjust the Tx level control (R256, near the ribbon cable) for a level of 650 mV p–p
on the oscilloscope (see Figure 28 on page 160 or Figure 29 on page 161).
1 Release PTT.
ALTERNATIVE TEXT
Drawing 08-05261 (sheet 2) or 08-05889 (sheet 2)
NOTE If the PCB issue status is -06 or earlier, see drawing 08-05889 (sheet 2).
NOTE
The transceiver must be in Service mode to perform this check (see
page 154, Accessing Service mode).
Signal
generator
Test unit
2030 Junction Box
with 2010 RF Unit,
or 2012 RF Unit
Signal
generator
Test unit
NGT test
handset
2011 RF Unit
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