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4 - 5
4-5 OTHER CIRCUITS
4-5-1 COMPOUNDER CIRCUIT (MAIN UNIT)
IC-F50/F51 have compounder circuit which can improve S/N
ratio and become wide dynamic range to suppress the
transmitting signal and to extend receiving signal. The circuit
is composed of the base band IC (MAIN unit; IC10).
(1) IN CASE OF TRANSMITTING
The audio signals from the microphone are applied to the
base band IC (IC10, pin 3) via microphone mute circuit
(FRONT unit; IC406), microphone amplifier (IC407), etc.
The signals are amplified at the amplifier section, and are
then applied to the compressor circuit to compress the audio
signals. The signals pass through (or bypass) scrambler
section, and are then amplified at limiter amplifier section
after being passed through the high-pass filter. The ampli-
fied signals pass through the low-pass filter section, and are
then applied to the modulation circuit (Q13, D16–D18) via
the FM/PM switch (IC11), low-pass filter (IC5) and D/A con-
verter (IC6).
(2) IN CASE OF RECEIVING
The demodulated AF signals from the IF IC are applied to
the amplifier section of base band IC (IC10, pin 23), and
then pass through the low-pass and high-pass filter section
to suppress unwanted signals. The filtered signals pass
through (or bypass) scrambler section, and are then applied
to the expander circuit to expand AF signals. The signals
pass through (or bypass) scrambler IC (IC14), and are then
applied to the analog switch (IC13, pins 8, 11). The signals
are applied to the base band IC’s amplifier section (IC10,
pins 19, 20), and are then applied to the AF amplifier circuit.
4
5
6
7
11
12
13
14
LEDR
LEDT
LIGT
AFON
DUSE
MCON
CSFT
SPON
Outputs RX LED control signal.
Low: Lights ON.
Outputs TX LED control signal.
Low: Lights ON.
Outputs back light LED control signal.
Low: Back light is ON.
Outputs audio control signal.
Low: Outputs audio signals from
speaker.
• Outputs CTCSS/DTCS switching sig-
nal when transmitting.
High: Selected DTCS.
• Outputs Min. VR switching signal
when receiving.
Low: Select Min VR.
NOTE:
Audio signals are prior to
transmitting.
Outputs microphone select signal.
High: While the internal microphone
is used.
Outputs shift signal for reference oscil-
lator’s frequency.
Outputs the internal speaker control
signal.
High: The internal speaker is select-
ed.
Pin
Port
Description
number
name
Scrambler/
De-scrambler
TX/RX
HPF
Pre-
emphasis
Limiter
Splatter
VR2
Expander
VR4
RXA2
SMF
De-
emphasis
Com-
pressor
VR1
(HPF)
RX
LPF
VR3
(HPF)
4
TXINO
7 MOD
18
19
20 SIGNAL
3
TXIN
22
RXINO
23
RXIN
21
SDEC
10
14
MDIR
9
MTDT
MTCK
13
MSCK
11
MDIO
12
MRDF
MSK
Modulator
MSK
Demodulator
MSK
BPF
Control
Register
TXA1
RXA1
• BASE BAND IC BLOCK DIAGRAM
4-6 PORT ALLOCATIONS
4-6-1 EXPANDER IC (FRONT UNIT; IC410)
Summary of Contents for VHF IC-F50
Page 1: ...SERVICE MANUAL VHF TRANSCEIVER ...
Page 31: ...R601 VHF B6034B 9 3 VR BOARD TOP VIEW BOTTOM VIEW 9 5 ...
Page 37: ......
Page 38: ...1 1 32 Kamiminami Hirano ku Osaka 547 0003 Japan S 14007IZ C1 2003 Icom Inc ...
Page 39: ...SERVICE MANUAL UHF TRANSCEIVER ...
Page 71: ...R601 B6034B 9 3 VR BOARD TOP VIEW BOTTOM VIEW 9 5 ...
Page 77: ......
Page 78: ...1 1 32 Kamiminami Hirano ku Osaka 547 0003 Japan S 14010IZ C1 2004 Icom Inc ...