13

3.4 Adjustments for

Technicians

1) Magnetron heater voltage

Magnetron heater voltage is formed at the MD
Board of the antenna unit and preadjusted at
the factory for use with any length of signal
cable. Therefore no adjustment is required.
However, verify heater voltage as follows:
CAUTION
Lift the radome cover slowly.
The antenna radiator may be caught by
the screw holes in the radome cover.
If you feel the radiator is caught by the
screw holes, lower the cover, turn it a
few degree and then lift it again.
Screw holes
(4 places)
Note: Turn the power on when measuring
magnetron heater voltage.
1. Dismount the shield plate.
MD board under
the shield plate
Figure 27 MD board
2. Turn on the power. Do not transmit the
radar.
3. Connect a multimeter, set to 10 V DC
range, between #6(+) and #4(-) of test
point TP804 on the MD Board in the
antenna unit.
4. Confirm that the multimeter shows 8.0 V
±0.1 V. If it does not, adjust potentiometer
VR801 on the MD Board.
TP804
VR851
VR801
Figure 28 Antenna unit, inside view