Raymarine e7 User Reference page 172

Function
Adjusting the radar tune control
From the radar application:
1. Select Menu.
2. Select Scanner Set-up.
3. Select Tune Adjust.
4. Select Tune Adjust.
Selecting Tune Adjust will switch the function between Auto
and Man.
5. In Manual mode use the Rotary Control to adjust the level, to
obtain the maximum signal strength (indicated by the eight-step
horizontal bar).
172
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e7 / e7D — User reference