Panasonic KX-TC1025RUB Service Manual ▷ View online
26.10.2.6. Attenuator control
The attenuator control detects the setting of the volume control through Pin 25 of IC601 to automatically adjust for changing
ambient conditions.
ambient conditions.
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KX-TC1025RUB
27
BLOCK
DIAGRAM
(Handset)
27.1.
Control
Block
TX DATA
RX DATA
1st
Mixer
Mixer
RX Filter
DUP101
ANT
RECEIVING FREQUENCY
30.075~30.300MHz
30.075~30.300MHz
1st
Local
Local
TX
Filter
Filter
DUP301
TX
AMP
AMP
TX
VCO
VCO
CONTROL
DATA
DATA
2nd
Mixer
Mixer
IF AMP DET
1st IF
Filter
Filter
2nd IF
Filter
Filter
DATA
Filter
Filter
DATA
AMP
AMP
PRE-
AMP
AMP
LINE
AMP
AMP
RECEIVER
150
150
Ω
EXPANDER
BATT LOW DET
/POWER DOWN
/POWER DOWN
MIC
Battery
COMPRESSOR
MODULATION
LIMITTER
PLL
X201
11.150MHz
11.150MHz
IC301
SENDING FREQUENCY
39.775~40.000MHz
39.775~40.000MHz
19.375
~19.600MHz
~19.600MHz
2nd Local 11.150MHz
1
2
3
2
3
X102
3.991MHz
X901
32.76KHz
MIC
AMP
AMP
CPU
IC901
IC101
CHARGE
DETECT
DETECT
RESET
TX Signal
RX Signal
51
KX-
TC102
TC102
5RUB
28 NEW CIRCUIT OPERATION (Handset)
28.1. Receiver RF IF Circuit
Circuit Operation:
The signal of 30 MHz band (30.075 MHz~30.300 MHz) is received at ANT is filtered by DUP101, and it is input to Pin
The signal of 30 MHz band (30.075 MHz~30.300 MHz) is received at ANT is filtered by DUP101, and it is input to Pin
of IC101.
The RX VCO which oscillates at T201 and IC101 is locked to 1st Local frequency by PLL inside IC101. (PLL is controlled by serial
data output from Pin
data output from Pin
,
and
of IC901.)
An input signal from Pin
of IC101 and 1st Local frequency output from RX VCO are mixed inside IC101, pass through CF1, and
1st IF frequency of 10.700 MHz is generated.
Further, 10.700 MHz and 11.150 MHz that oscillated at X101, pass through MIXER inside IC101 and are filtered at CF2 and output
2nd IF 450 kHz.
Further, 10.700 MHz and 11.150 MHz that oscillated at X101, pass through MIXER inside IC101 and are filtered at CF2 and output
2nd IF 450 kHz.
52
KX-TC1025RUB
28.2. Receiver Signal Circuit
Circuit Operation:
After getting the 450kHz signal, it is input to Pin
After getting the 450kHz signal, it is input to Pin
of IC101 and passes through IF AMP and Detector Circuit, then are output to
Pin
. It is an AF signal flows through R123, C124. Its level is controlled by the VOLUME CONTROL Amp of IC101.
The signal is received at Pin
of IC101, then it passes through the following circuits: PREAMP, Expander and Amplifier: It goes
out at Pin
and finally is sent to the SP.
Inside IC101, RX-MUTE, MIC-MUTE and PLL circuits are controlled by the serial data that the CPU send from Pins
,
and
.
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KX-TC1025RUB
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