Kenwood NXR-700 Service Manual page 14

NXR-700
3-7. FAN action control circuit
The FAN action control circuit consists of a FAN and a
AVR (IC12)
VBATT
IC12
AVR
M
Fig. 13 FAN action control circuit
3-8. Current detector circuit
The current detector circuit monitors the current of the
Power Amplifi er Module. It consists of a current detection
resistance (R4) and a current detection IC (IC1). It detects
the normal and abnormal state of the Power Amplifi er Mod-
ule by monitoring the current of the Power Amplifi er Module.
If a failure occurs, it stops operation.
Fig. 14 Current detector circuit
3-9. AVR circuit
IC3, IC11 and IC12 are AVR ICs.
They maintain isolation of each power supply.
+VBATT
CN2
IC11
+8V
IC12
+12V
Fig. 15 AVR circuit
14
CIRCUIT DESCRIPTION
FAN_CONT
IC1
Current PA_CURR
sense IC
IC10
Power amplifier
module
IC2,4,5,8
OP AMP
Q5,7
SW
ANT SW
IC3
IC6
+5V OP AMP
IC7
Temp
protection IC
IC1
Current
detector IC
FAN
3-10. Other circuits
Circuit IC9 saves various adjustment values of the Final
Unit in the EEPROM.
4. Receiver Unit
The receiver unit (X55-309) consists of the following cir-
cuits:
(1) Front-end circuit
(2) 1st-Mixer circuit
(3) 1st-IF circuits
(4) Demodulator circuits
(5) Squelch circuit
(6) Receiver DDS circuit
(7) Receiver PLL circuits
(8) AVR circuit
(9) Other circuits
There are fi ve modulating modes that can receiver de-
modulate, including Analog_Wide_5k, Analog_Wide_4k,
Analog_Narrow, NXDN_Narrow, and NXDN_Very-Narrow.
4-1. Front-end circuit
The front-end circuit consists of L132, L133, L134, and
L135 coils, tetra polar BPF synchronizing TC1, TC2, TC3
and TC4 variable trimming capacitors, Q1 Low Noise Ampli-
fi er (LNA), L136, L137, L138, L139 coils, and tetra polar BPF
synchronizing TC5, TC6, TC7, and TC8 variable trimming
capacitors.
Adjusting eight variable trimming capacitors forms the
BPF having a pass band width of 3MHz with a center fre-
quency from 136 to 154MHz.
+9V is applied to the Q1 collector power supply.
collector current is monitored by the IC4 current detection
circuit. Detected DC voltage is input to pin 15 of IC30 (ADC).
RX unit
RX ANT
X55-309
BPF
CN5
L132~135
TC1~4
Fig. 16 Front-end circuit
The
+9V
IC30
15
IC4
Q1
BPF
LNA
L136~139
TC5~8