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6 suppressing main bang – Furuno FR1500 Mk3 User Manual

Page 54

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5-5

VIDEO SIGNAL

Video Level
Approx. 4.0 Vpp

±

0.2 V

Gate for video
adjustment

Video Level
Approx. 4.5 Vpp

Main Bang

Adjust the EEPOT (U92) on the pcb 03P9230 so average
video level is 4.0 Vpp

±

0.2 V during this interval.

Timing Correct

Timing Wrong

Figure 5-7 Video signal timing

5.6 Suppressing Main Bang

If main bang appears at the screen center, suppress it as follows:

1. Transmit on a long range and then wait ten minutes.

2. Adjust the GAIN control to show a slight amount of noise on the display.

3. Select the 0.25 nm range. Adjust the A/C SEA control to suppress sea clutter.

4. Press [MENU] [0] [0] [0] [0] [5] [5] [5] to select MBS-T from the SET UP 1

menu.

5. Adjust the VRM control to adjust MBS timing (Adjustable range: 0-127).

6. Press the [ENTER/SELECT] key.

7. Press the [6] key to select MBS-L (MBS-Level).

8. Adjust the VRM control to adjust MBS level (Adjustable range: 0-127).

9. Press the [ENTER/SELECT] key.