NGT—Checks and adjustments
182 NGT Transceiver System Technical Service Manual
The indicated PEP level with two-tone modulation depends on the type of
measuring instrument, as shown in Table 48 on page 181.
1 Release PTT.
1 Check that the two-tone waveform is clean and undistorted.
If it is not clean and undistorted, further analysis is required.
Adjusting low output power
To adjust the low output power:
1 Select any test channel frequency between 4 and 6 MHz (for example, test
channel 16).
1 Press 7 to select low power.
1 Proceed as for page 180, Adjusting high output power.
1 Adjust LO PWR (R35) for 12 W PEP (5 W on an average reading meter) (see
Figure 33 on page 163 or Figure 34 on page 163 and Table 48 on page 181).
1 Check that the two-tone waveform is clean and undistorted.
If it is not clean and undistorted, further analysis is required.
Adjusting the bias gain
To adjust the bias gain:
1 Connect a 50 Ω dummy load to the RF connector ( ) (see Figure 43).
1 Connect a spectrum analyser via a 47 kΩ resistor to the RF connector (see
Figure 43).
This provides a low-level output for the spectrum analyser.
ALTERNATIVE TEXT
Drawing 08-05416 or 08-05910 (sheet 1)
NOTE If the PCB issue status is -04 or earlier, see drawing 08-05910 (sheet 1).
NOTE
Before adjusting the low output power, set the high output power (see
page 180, Adjusting high output power).
NOTE
The transceiver must be in Service mode to make this adjustment (see
page 154, Accessing Service mode).
ALTERNATIVE TEXT
Drawing 08-05415 or 08-05511 (sheet 1)
NOTE The bias gain must be set before any intermodulation tests are performed.
NOTE
The transceiver must be in Service mode to make this adjustment (see
page 154, Accessing Service mode).
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