3 - 3
• 1st LO GENERATOR CIRCUIT
DDS circuit is employed for LO signal generation; no
PLL circuit is used with the IC-7200. This provides
extremely high frequency stability against temperature
and vibration.
The 32 MHz reference frequency signal from the TCXO
(X2011) is buffer-amplified by Q2011 and amplified by
IC2011. The 8th harmonic component (256 MHz) in the 32
MHz reference frequency signal is extracted and amplified
by IC2151 to the level needed for the DDS. The amplified
256 MHz reference signal is applied to the DDS (IC2541)
as the master clock signal.
The 32.2425–64.2275 MHz signals are output from the
DDS, and doubled by D2572. The doubled signals are
used as the 1st LO frequencies. The 1st LO signals are
amplified by IC2601, filtered by the appropriate BPF to
remove unwanted frequency components, then applied
to the 1st LO AMP.
• OTHER LO GENERATOR CIRCUIT
The 32 MHz reference signal is also used for the another
DDSs of 2nd and 3rd LO signal generation, as well as the
DSP.
The 32 MHz reference signal from IC2011 is adjusted
its wave form, and divided by two by IC2042, then the
divided reference signal (16 MHz) is applied to the DDS
(IC2043) as the master clock signal. The DDS outputs
439.375 kHz signal as the 3rd LO.
The doubled reference signal (64 MHz) signal is
amplified by IC2091, and used as the 2nd LO.
3-3 PA UNIT
The PA UNIT is composed by power AMP which
amplifies the YGR output signal from the RF UNIT to the
TX output power, power supply line control circuits and
cooling fan control circuit.
• POWER AMP
The TX signal from the RF UNIT is amplified by the pre-
drive AMP (Q1) on the entire band (HF to 50MHz band).
The amplified TX signal is passed through L1, and
amplified by the push-pulled drive AMP (Q2, Q3). These
AMPs (Q1 to Q3) are individually gain-adjusted so that
the frequency characteristic of TX signal is flat one by
feeding back the 180-degree phase-shifted signal.
The amplified TX signal from the drive AMP (Q2, Q3)
is passed through L2 and applied to the power AMP
(Q4, Q5). The TX signal is power-amplified to the 100 W
(max.) of output power. The power-amplified TX signal is
entered to the FILTER UNIT via J9, and passed through
a BPF corresponds to the TX frequency.
• POWER SUPPLY LINE
When the power SW on the FRONT panel is pushed,
Q7 turns RL1 ON and the 13.8 V DC is supplied to the
“P14V” line.
• COOLING FAN CONTROL CIRCUIT
The cooling fan control circuit is also equipped on the
PA UNIT. The cooling fan control voltage “FANV” is
applied to the base terminal of Q131, and the change of
the volatage causes the rotation speed of cooling fan.
3-4 FILTER UNIT
The FILTER UNIT is composed by LPFs which reduces
the harmonic components in the TX signal to be less than
–50 dB.
• LPF
The LPF stage is composed by seven Chebyshev-typed
LPFs which have different cut-off frequencies. The TX
signal passes through the one of 7 LPF according to the
TX frequency. A switching relay is used for LPF selection
on both input and output terminals for each LPF.
IF Signal
Frequency
LO Signal
Frequency
1st RX IF
64.455 MHz
1st RX LO
64.485–124.455 MHz
2nd RX IF
455 kHz
2nd RX LO
64.000 MHz
3rd RX IF
15.625 kHz
3rd RX LO
439.375 kHz
3rd TX IF
15.625 kHz
3rd TX LO
439.375 kHz
2nd TX IF
455 kHz
2nd TX LO
64.000 MHz
1st TX IF
64.455 MHz
1st TX LO
64.485–124.455 MHz
TX signal
(*)
–
–
*; Refer to "
SPECIFICATIONS
."
• FREQUENCY CONFIGURATION
LPF
LPF
LPF
LPF
LPF
LPF
SW12
S2
SW12
S3
SW12
S4
SW12
S5
SW12
S6
SW12
S7
SW12
S8
SW12
S9
SW12
S10
SW12
S11
SW12
S12
SW12
S13
PWR
AM P
DRIVE
AMP
DRIVE
PRE
ATT
YGR
AM P
LPF
SW12
S13
SW12
S7
FILTER UNIT
PA UNIT
<2.0MHz
2.0-5.0 MHz
5.0-8.0 MHz
8.0-15.0 MHz
15.0-22.0 MHz
22.0-30.0 MHz
To antenna
From BPFs
Q2,Q3
Q4,Q5
Q1
IC181
30.0-54.0 MHz
RF UNIT
• USB CONTROLLER
By connecting the PC through the USB connector
(J3202; type B), IC-7200 can be controlled by a PC.
The communication with the PC is accomplished by
connecting to the USB audio IC (IC3202) and UART
bridge (IC3203) through the USB hub (IC3201).
IC3202 converts the analog AF signals into the digital
audio signals (A/D conversion), and converts the digital
audio signals from the PC into the analog AF signals
(D/A conversion). IC3203 controls the transceiver from
connected PC using CI-V commands.
- TX AMPLIFIERS AND LPFs -
Содержание IC-7200
Страница 1: ...SERVICE MANUAL ADDENDUM CONTENTS PARTS LIST 1 BOARD LAYOUTS 19 VOLTAGE DIAGRAM 21 Jun 2009 ...
Страница 33: ...Oct 2008 SERVICE MANUAL ADDENDUM CONTENTS BOARD LAYOUTS LOGIC AND MAIN UNITS 1 Nov 2008 ...
Страница 38: ...Oct 2008 SERVICE MANUAL ADDENDUM CONTENTS BOARD LAYOUTS RF AND MAIN UNITS 1 Oct 2008 ...
Страница 41: ...Oct 2008 SERVICE MANUAL ADDENDUM CONTENTS PARTS LIST 1 BOARD LAYOUTS 16 VOLTAGE DIAGRAM 22 Oct 2008 ...
Страница 74: ...S 14513XZ C1 Oct 2008 HF 50MHz TRANSCEIVER ...
Страница 135: ...1 1 32 Kamiminami Hirano ku Osaka 547 0003 Japan S 14513XZ C1 2008 Icom Inc ...