Codan NGT 2010 RF Technical & Service Manual page 211

Drawing
ALTERNATIVE TEXT
NOTE
To adjust the driver bias:
1
1
1
1
1
1
1
1
1
1
Drawing
ALTERNATIVE TEXT
NOTE
To adjust the driver bias:
1
1
1
1
1
1
1
NGT Transceiver System Technical Service Manual
08-05869 (sheet 2)
The transceiver must be in Service mode to make this adjustment (see
page 154, Accessing Service
Ensure the transceiver is switched off and the DC supply is disconnected.
Disconnect the exciter output from the PA by removing the connector from J2 (Tx
coaxial) on the RF/IF PCB in the RF unit (drawing
(sheet 1)).
Unsolder the link labelled DR (DC supply to the driver transistors V207 and V208)
(see Figure 31 on page
Set a multimeter to DC 20 mA range and connect it in place of the removed link.
Connect the DC supply, then switch on the transceiver.
Select any transmit channel, then hold down PTT.
Check that the driver current measures 13 mA ±2 mA.
If the current is out of the specified limit stated above, change it by adjusting DR
BIAS (R222) (see Figure 31 on page
Release PTT.
Switch off the transceiver, disconnect the multimeter, then replace the link with a
length of tinned copper wire.
08-06461 (sheet 2)
The transceiver must be in Service mode to make this adjustment (see
page 154, Accessing Service
Ensure the transceiver is switched off and the DC supply is disconnected.
Disconnect the exciter output from the PA by removing the connector from J2 (Tx
coaxial) on the RF/IF PCB in the RF unit (drawing
Unsolder the link labelled DR (DC supply to the driver FETs V207 and V208) (see
Figure 32 on page 162).
Set a multimeter to DC 200 mA range and connect it in place of the removed link.
Connect the DC supply, then switch on the transceiver.
Select any transmit channel, then hold down PTT.
Check that the driver current measures 40 mA ±2 mA.
mode).
162).
162).
mode).
NGT—Checks and adjustments
08-05261 (sheet 1) or
08-05889 (sheet 1)).
08-05889
177