Furuno FS-1570 Service Manual page 172

(d)
Change C and L and then retry pi
matching.
SWR< 2.0?
YES
TUNE OK
Change C and L and then retry pi
matching.
SWR< 2.0?
YES
TUNE OK
5-55
5.8 Antenna coupler, AT-1560
NO
NO
DIP switch
SW4 is ON?
NO
TUNE ERROR
Select the best circuit
you have tried.
SWR< 3.0?
YES
TUNE OK
YES
NO
TUNE ERROR