JRC JAN-701B Instruction Manual page 402

Tip of RADAR Range and Bearing
① Adjusting Bearing
Expand the screen display. Then, adjust Heading echo to Bearing.
Heading echo
② Adjusting Range
Expand the screen display. If there is the hole of own ship's echo,
adjust Range smaller until the hole disappears.
Hole of own
ship's echo
7 Tools and Setting/Serviceman Menu 7-24