Adjusting Carrier Re-Insertion - Codan NGT 2010 RF Technical & Service Manual

Adjusting carrier re-insertion

Drawing
ALTERNATIVE TEXT
NOTE
NOTE
NOTE
To adjust carrier re-insertion:
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Figure 42: Graph showing adjustment to 90% modulation
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NGT Transceiver System Technical Service Manual
08-05261 (sheet 2)
If the PCB issue status is -06 or earlier, see drawing
The exciter output level must be set before this adjustment is made (see
page 170, Adjusting the exciter output
The transceiver must be in Service mode to perform this check (see
page 154, Accessing Service
Select test channel 16 with AM mode.
Unplug the coaxial cable between the PA PCB and the RF/IF PCB in the RF unit.
Connect an oscilloscope with a 50 Ω termination to the Tx test point on the
RF/IF PCB.
Using the transceiver test unit, apply an audio signal of 1 kHz at a level of
300 mV p–p to:
• the audio input on the 15-way GPIO connector on the junction box or 2012 RF
Unit (see Figure 40 on page
• the 2011 RF Unit via the NGT test handset (see
Hold down PTT.
Adjust R217 (near the SSB filter Z201) for 100% modulation.
Rotate R217 clockwise to set it to approximately 90% modulation (see
Release PTT.
or 08-05889 (sheet 2)
mode).
170), or
NGT—Checks and adjustments
08-05889 (sheet
level).
Figure 41 on page
6 Div
¼ Div
2).
170)
Figure 42).
171