Aligning The Tx Filter - Codan NGT 2010 RF Technical & Service Manual

NGT—Checks and adjustments
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Aligning the Tx filter

Drawing
ALTERNATIVE TEXT
NOTE
NOTE
To align the 45 MHz Tx filter:
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1
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Figure 39: Transmit sweep test display
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168
Select any other channel to stop the sweep test.
08-05261 (sheet 2)
If the PCB issue status is -06 or earlier, see drawing
The transceiver must be in Service mode to perform this check (see
page 154, Accessing Service
Connect the Tx exciter output on the RF/IF PCB in the RF unit to channel 1 of an
oscilloscope terminated with 50 Ω.
Set the channel 1 input to AC at 100 mV per division.
Set the timebase of the oscilloscope to 5 ms per division.
Connect the TRIG test point on the RF/IF PCB to the external trigger of the
oscilloscope.
Set the oscilloscope for an external positive trigger and adjust for lock.
Set the transceiver to channel 5 to initiate the transmit sweep test.
Adjust the trace to the centre position.
Adjust T107, L117 and T108 for a flat response as shown in
The amplitude depends on the setting of the preset carrier level
NOTE
potentiometer R217.
Select any other channel to stop the sweep test.
or 08-05889 (sheet 2)
mode).
NGT Transceiver System Technical Service Manual
08-05889 (sheet 2).
Figure 39.