Onwa KR-1338 Service Manual page 31

ANT height setting
Setting in the field
Antenna height (STC curve adjustment) should be set
Radar at installation to match the STC curve with
installation conditions. This is especially important
when sea conditions changes over time - rotation of
the STC VR may erase both sea clutter and legitimate
targets if the STC curve is not suitable.
1. Set antenna height on the Installation Setup 1 menu
If both sea clutter and echoes disappear, decrease
antenna height setting. If sea clutter cannot be comp-
letely eliminated, increase antenna height setting.
2. Adjust Vr2 on the SPU board. If both sea clutter and
targets disappear: increase voltage at 60 us point.
Note: The following step, adjustment of the STC,
should only be followed when step 1 and 2 do
not produce satisfactory results. Record the
factory setting before adjusting the STC.
3. Adjust STC. (Press the MENU key five times while
pressing and holding down the HM OFF control to
display the FACTORY menu. Operate the trackball to
change the maximum effective range of the STC.
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