Furuno FR-2155, Service Manual

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Switching coil L802 conducts after CR813 to CR815 become on completely, in order to mini-
mize wasted heat energy. CR816/CR817/CR818 and R816/R817/R818 absorb the counter elec-
tromotive force developed at the moment CR813/CR814/CR815 are turned off, protecting
CR813/CR814/CR815 from damage. CR808 and CR809 absorb rising of pulse in the secondary
of T801. C804 decouples the pulse energy that is liable to occur across the magnetron heater
when T801 secondary windings are unbalanced or the load is asymmetric.
Figure 2.19 Rising of pulse absorbed by Cr804 and CR815
Duplexer and mixer
Since the radar system uses a single antenna for transmission and reception, an efficient device is
required for switching the transmitter and the receiver. This radar employs circulator HY801 for
this purpose.
U801
V801 3
IF OUT
2 1 5~35V
H
GND
+5V
V801
HY801 CR810
DI MONIT
Magnetron
Circulator TR limiter MIC
Eliminated by CR808/CR809.
Voltage
T/2
2Vo
Vo
Pulse
t=2N
√
L
×
C
Trigger Trigger Time
Holding time Holding time
Figure 2.18 Changing the PFN
Figure 2.20 Circulator HY801