Furuno FR-1500 Operator's Manual page 100

12 nm
4 arcs starting at 12 nm
Transmitter: normal
Receiver: normal
9 nm
Transmitter: 3 dB loss
(Transmitter system has lost a
half of initial power. Suspect
magnetron.)
Receiver: normal
-7.2-
9 nm
Transmitter: 3 dB loss
(Transmitter system has lost a
half of initial power. Suspect
magnetron.)
Receiver: 3 dB loss (Receiver
has lost a half of initial
sensitivity. Suspect receiver
front end, water ingress in
feeder system, etc.)