Aligning The 45 Mhz Filters; Aligning The Rx Filter - Codan NGT 2010 RF Technical & Service Manual

Aligning the 45 MHz filters

Aligning the Rx filter

Drawing
ALTERNATIVE TEXT
NOTE
NOTE
To align the 45 MHz Rx filter:
1
1
1
1
1
1
1
1
1
1
Figure 38: Receive sweep test display
NGT Transceiver System Technical Service Manual
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 a signal generator to the receiver input of the transceiver.
Set the signal generator to 8.4 MHz at –40 dBm (2 mV).
Connect a 10× probe on channel 1 of an oscilloscope to TP201 on the RF/IF PCB.
Set the channel 1 input to AC at 20 mV per division (200 mV per division with 10×
probe).
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 4 to initiate the receive sweep test.
Adjust the trace to the centre position.
Adjust T104, L110, L111 and T105 for a flat response as shown in
NOTE With 08-05889, spikes on the waveform are normal.
or 08-05889 (sheet 2)
mode).
NGT—Checks and adjustments
08-05889 (sheet 2).
Figure 38.
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