Icom IC-R100 Service Manual page 11

50.0—905.0MHz
N RF
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О
905.0--1856.0 MHz
О
V 1st LO
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V
630MHz
SERIAL
DATA
x1
g
J 12.6 MHz
4-3-4 VCO CIRCUIT (PLL UNIT)
Each of the 4 VCO's oscillates a different frequency on
the TUNER UNIT (EP2). The Fig. 7, 8 shows the relations
between VCO and oscillation frequency.
Fig. 8
The signals are buffer-amplified at IC4 and then applied
to IC3 (pin 8). The buffer amplifier (IC4) protects the
PLL output signal against VCO oscillation.
4-3-5 DC-DC CONVERTER CIRCUIT
(PLL UNIT)
IC5 is a DC-DC converter which creates approximately
30 V DC from 10 V DC to obtain wide range lock voltages
for the PLL circuit.
Fig. 7
TUNER UNIT(EP2)
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1
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IF OUT
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45.995—
| i 46.004 MHz
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Гм
LOOP
FILTER
4-4 POWER SUPPLY СТВСЏТ5
4-4-1 VOLTAGE LINES
LINE DESCRIPTION
13.8 V DC controlled by the PWS signal line.
5V Common 5 V converted from the 13.8 V line at
IC 9 on the MAIN UNIT.
10 V DC converted from the 13.8 V line. IC8
on the MAIN UNIT is a switching regulator IC
and converts IC5 output into approx. 30 V DC.
4-4-1 SWITCHING CIRCUIT (MAIN UNIT)
This circuit consists of Q17, Q18 and Q30. The circuit
corresponds to the high-rippled DC voltage which an AC
adapter contains. When a ripple is present in DC voltage,
a ripple filter (C129, R132) eliminates the ripple to obtain
clear reception.