Codan NGT 2010 RF Technical & Service Manual page 215

Table 48: Power output PEP vs measuring instrument (12/100/125 W)
Power Output PEP
Peak reading meter
RMS reading meter
Average reading meter (e.g.
Bird Model 43)
Oscilloscope
1
1
Drawing
ALTERNATIVE TEXT
NOTE
NOTE
NOTE
To adjust the high output power:
1
1
1
1
1
1
1
1
1
NGT Transceiver System Technical Service Manual
Release PTT.
Check that the two-tone waveform is clean and undistorted.
If it is not clean and undistorted, further analysis is required.
08-05910 (sheet 1)
If the PCB issue status is -04 or earlier, see drawing
The transceiver does not have to be in Service mode to make this
adjustment.
The output power is factory-set, so it is not likely to be outside the
specified limits. Check that there are no faults with the transmitter circuits
before attempting to adjust the output power.
Select any channel frequency between 4 and 6 MHz.
Connect an average or PEP power meter with a 50 Ω dummy load to the RF
connector ( ).
Connect an oscilloscope via a 47 kΩ resistor to the antenna connector.
Set the oscilloscope timebase to 500 µs per division and the trigger to auto.
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 on page
• the 2011 RF Unit via the NGT test handset (see
Hold down PTT, then adjust the two-tone level for compression.
Adjust the Y sensitivity of the oscilloscope for on-screen display and adjust the
trigger for a stationary waveform.
Adjust the two-tone balance control for good crossover display.
Adjust HI PWR (R32) (see
12 W
12 W
6 W
5 W
69 V p–p 200 V p–p
170), or
Figure 34 on page 163) for the required output.
NGT—Checks and adjustments
100 W 125 W
100 W 125 W
50 W 62.5 W
40.5 W 50.6 W
224 V p–p
08-05910 (sheet
Figure 41 on page 170)
1).
181