Tx/Rx 05P0774 - Furuno FM-8800D Service Manual

APC, R VSWR, F VSWR CIRCUIT
CM Coupler
Tx out
U2
(DCS3D20)
These power data set up by [MENU] -> SYSTEM -> TX POWER: is inputted into U4
(1/2): inversion amplifier. This voltage is a reference voltage of U4. One the other hand,
F-VSWR detected by CM coupler is detected by CR8 (half-wave detection) and is
amplified by U3 (1/2). R-VSWR is detected by CR5 and 6 (full-wave detection) and is
amplified on U3 (2/2). For example, when PWR CONT inputted into U4 (1/2) is lower
than F-VSWR voltage, U4 (1/2) output decreases. It lowers the base current of Q10 and
goes through Q2 to lower V
decreases as well. This voltage is the same as PWR CONT and continues until it reaches
voltage value.
Rx
(4)
PA
T/R
LPF
SW U1(RA35H1516M)
V
(2)
GG
T15V
PWR CONT
Q102
Q2
Q1:Driver Bias
Q10
T15V1
TEST ON
Q8
Not used
F-VSWR DET
R52
CR8
U3(1/2)
R-VSWR DET
CR103
CR6, 5
U3(2/2)
Fig. 5.4.7 APC Block
of U1: and PA output. As a result, F-VSWR voltage
GG
5-14
Driver
(1)
Q1
V
(3)
DD
Q1:Driver Bias
T15V
UN LOCK
Q11
(From U12: PLL IC)
TEST ON
U4
Not used
- +
(1/2)
PWR CONT
U4
F VSWR
R VSWR
TX/RX
05P0774
5.4 Block Description
CPU
05P0773
U30
CPU
DA
CPU
AD
EEPROM