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4-3-3 UHF LOOP
The generated signal at the U-VCO (Q20, Q21, D20, D21)
enters the PLL IC (IC2, pin 15) via buffer-amplifiers (Q22,
Q23) and is divided at the programmable divider section and
is then applied to the phase detector section.
The phase detector compares the input signal with a refer-
ence frequency, and then outputs the out-of-phase signal
(pulse-type signal) from pin 13.
The pulse-type signal is converted into DC voltage (lock volt-
age) at the loop filter (Q101, Q102, R538, C481, C483), and
then applied to the U-VCO to stabilize the oscillated frequen-
cy.
• PLL circuit
Q99, Q100
Loop
filter
8
Phase
detector
X1
15.2 MHz
19
Programmable
divider
1
13
Phase
detector
Q101, Q102
Loop
filter
V-VCO
Q6
Buffer
Q4, Q5, D3
PLL IC (IC2)
Programmable
Prescaler
counter
Shift register/
data latch
Programmable
Prescaler
counter
U-VCO
Q22
Buffer
Q20, Q21
D20, D21
Tripler
BPF
4-4 POWER SUPPLY CIRCUITS
• VOLTAGE LINE
Line
The 13.8V external DC power from the power
HV
connector.
The same voltage as the HV line which is con-
trolled by the power switching circuit (Q74, Q75).
When the [POWER] switch is pushed, the CPU
13.8V
outputs the "PCTRL" control signal to the power
switching circuit to turn the circuit ON.
Common 5 V for the CPU converted from the HV
line by the C5V regulator circuit (IC15). The cir-
C5V
cuit outputs the voltage regardless of the power
ON/OFF condition.
Common 5 V produced from the C5V at the
PLL5V regulator circuit (Q13, Q14) using control
PLL5V
signal from 8V line.
Common 8 V converted from the 13.8V line by
8V
the 8V regulator circuit (IC14).
VHF transmit 8 V converted from the 8V line at
VT8V
the VT8V regulator circuit (Q9, Q10).
UHF transmit 8V converted from the 8V line at
UT8V
the UT8V regulator circuit (Q25, Q26).
Receive VR8V produced from the 8V line at the
VR8V
V-BIAS selector (Q34, Q35).
Receive 4R8V produced from the 8V line at the
4R8V
U-BIAS selector (Q34, Q36).
Receive UR8V produced from the 4R8V line at
UR8V
the UR8V switching circuit (D28, D29).
Q7
Buffer
Q8
Buffer
6
2 DATA
3 CK
4 PLSTB
15
Q23
Buffer
Q24
Buffer
15.2 MHz
to the FM IF IC (IC28)
45.6 MHz
to the FM IF IC (IC8)
4 - 5
Description
D4
to VHF transmitter circuit
to VHF 1st mixer circuit
D22
to UHF 1st mixer circuit
D23
to UHF transmitter circuit
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