Kenwood NXR-800 Service Manual page 18

NXR-800
Q52
+B
SW
CN44
4-9. Other circuits
Other circuits include the EEPROM (IC31), the temper-
ature sensor IC (IC35), the DAC (IC23) and the ADC (IC30).
IC31 saves various adjustment values of the receiver unit.
IC35 is built-in for detecting changes in temperature. IC23
offsets the RSSI voltage (pin1) (detected by the IF system
IC (IC12)) and the 1st-VCO_A, VCO_B control voltage (pin2,
pin3).
IC30 monitors the 1st-VCO control voltage (pin16), the
LNA current detection value (pin15), the temperature de-
tected by the temperature sensor IC (IC35 pin14), the RSSI
voltage detected by the IF system IC (IC12 pin12), the
squelch voltage detected by the IF system IC (IC12 pin11),
and the control voltage of the 2nd-VCO (pin10), and outputs
each state in serial data (IC30 pin18), sends the signal from
CN42 (pin22) to the control unit (X53-413). The signal is pro-
cessed by the MPU.
18
CIRCUIT DESCRIPTION
IC24
+8V
Q32
SW
Q25
SW
IC15
+5V
IC25
+8V
IC26
+9V
IC701 IC702 IC703
+5V –5V –3V
IC27
+9V
Fig. 22 AVR circuit
IC16
Q18,23
+5V
1st local amplifiers
IC17
Q19,28
+5V
WIDE pass
Q20,29
Narrow pass
IC12
IF system IC
IC18
+5V
IC19
Q1
+5V
LNA (Collector)
Q1
LNA (Emitter)
Q9
Q27
Q6
IC32
A/2
1st
VCO_A
1st
VCO_B
IC33
2nd CV
IC12
ASQL
IC12
RSSI
IC35
TEMP.
IC4
LNA
IC6
1st CV
Fig. 23 Other circuits
IC13
IF systemIC
Q21,53
2nd local amplifiers
IC10
IC19
+3V
Pre-scaler
IC22
IC14
+3.3V
2nd IF amplifier
IC5,11
1st/2nd PLLʹs
IC7
DDS
Q17,33
1st/2nd VCO buffer amplifiers
Q7,8
1st local VCOʹs
Q24
2nd local VCO
Q2,4
active loop filter
1
6
IC23
2
7
3 8
10 18
11
IC31
12
EEPROM
IC30
5
14
6
15
CN42
16
11
9
8
22
32
30