Codan NGT 2010 RF Technical & Service Manual page 555

Adjusting the ALC bridge
Drawing
NOTE
To adjust the ALC bridge:
1
1
1
1
1
1
1
1
1
1
Adjusting the power supply frequency
Drawing
NOTE
To adjust the power supply frequency:
1
1
1
1
1
1
1
NGT Transceiver System Technical Service Manual
08-05985
The transceiver does not have to be in Service mode to perform this
adjustment.
Connect setup as per page 180, Adjusting high output
Select any channel near 15 MHz.
Attach a load-matching transformer between the load and the amplifier output, so
that the amplifier is presented with a 16.7 Ω load.
Hold down PTT.
Adjust the capacitor C5 to give 150 W (3061) or 300 W (3062) PEP into the load.
Release PTT.
Reverse the load-matching transformer to present a 150 Ω load.
Hold down PTT, then check that the output power into the load is the same.
Release PTT.
If necessary, re-adjust the capacitor to give the same power for both load cases.
The High VSWR LED may illuminate while this adjustment is
NOTE
made. Switch the transceiver off then on again to reset this LED.
08-05978 (sheet 1),
The transceiver does not have to be in Service mode to perform this
adjustment.
Switch off the NGT and remove solder link X1 from the Power Supply PCB in the
power amplifier.
Ensure there is no audio drive to the NGT.
Hold down PTT.
Using a frequency counter on TP1, adjust R17 to give a frequency of 70 kHz
±100 Hz.
Using a frequency counter on TP101, adjust R117 to give a frequency of 63 kHz
±100 Hz.
Release PTT.
Switch off the NGT and resolder link X1.
08-05978 (sheet 2) and
High power—Fault finding and adjustments
power.
08-05978 (sheet 3)
241