Icom IC-7000, Service Manual, Page: 10 / 92

3-2-5 2ND MIXER CIRCUIT (MAIN UNIT)
The 2nd mixer circuit mixes the 2nd IF signal with the 2nd
LO signal to convert into the 1st IF frequency.
The filtered signal from the bandpass filter (FI901) is applied
to the 2nd mixer circuit (D801) and mixed with 2nd LO sig-
nal (124.032 MHz) to convert into the 1st IF signal.
The 2nd LO signal is generated in the DDS unit, and applied
to the 2nd mixer circuit (D801) after being filtered and
attenuated at the low-pass filter (L808, C816, C817) and the
attenuators (R801, R805, R806, R809–R811), respectively.
The converted 1st IF signal is applied to the 1st IF circuit.
3-2-6 1ST IF CIRCUIT (MAIN UNIT)
The 1st IF circuit amplifies and filters the 1st IF signal.
The converted 1st IF signal is applied to the IF amplifier
(Q701) via the TX switch (D703) and then passed through
the bandpass filter (FI601) to suppress unwanted signals via
the filter switches (D601, D602).
The filtered signals are applied to the 1st mixer circuit.
3-2-7 1ST MIXER CIRCUIT (MAIN UNIT)
The 1st mixer circuit mixes the 1st IF signal with the 1st LO
signal to convert into the RF frequency.
The filtered signal is applied to the 1st mixer circuit (IC401)
via the TX switches (D501, D504) and mixed with the 1st LO
signal (124.517–594.487 MHz) to convert into the RF signal.
The 1st LO signal is generated in the DDS unit, and applied
to the 1st mixer circuit (IC401, pins 1, 6) after being ampli-
fied and attenuated at the 1st LO amplifier (IC421, pins 1, 4)
and the attenuators (R416–R418, R421–R423), respectively.
The converted RF signal is applied to the RF circuit.
3-2-8 RF CIRCUIT (MAIN UNIT)
The RF circuit amplifies and filters the RF signal from the
1st mixer circuit.
The HF/50 MHz bands signal from the 1st mixer circuit
(IC401) is passed through the low-pass filter (L310, L312,
C314, C316, C318, C320, C322) via the band switch (D305).
The HF band signal is passed through one of 5 high-pass
(Refer to 3-1 for used RF high-pass filter) and low-pass
(L205, L207, C209–C213) filters.
The 50 MHz band signal is passed through the bandpass
filter (L219, L220, L246–L248, C240–C242, C282, C285–
C291).
The filtered HF/50 MHz bands signal is amplified at the YGR
amplifier (IC1) after passed through the high-pass filter (L109,
L110, L116, L117, C109, C114–C116) and attenuator (R5–
R7).
The amplified HF/50 MHz bands signal is applied to the
drive and power amplifier circuits (PA unit) via J1.
The VHF/UHF bands signal from the 1st mixer circuit (IC401)
is passed through the low-pass filter (L309, L311, L313,
C313, C315, C317, C319, C321, C323, C325) via the band
switch (D306).
The VHF band signal is passed through the bandpass filter
(L8, L10–L13, C18, C25, C26, C28, C29, C31–C33) via
the band switches (D3, D10) and then amplified at the RF
amplifier (IC2, pins 1, 3). The amplified signal is passed
through the band switch (D1) and attenuator (R5–R7), and
then applied to the YGR amplifier (IC1, pins 1, 4).
The amplified signal is passed through the high pass filter
(L21, C50–C52) via the filter switches (D6, D8) and then
applied to the drive and power amplifier circuits (PA unit) via
J1.
The UHF band signal is amplified at the RF amplifier (IC3,
pins 1, 3) via the band switch (D4) and passed through the
bandpass filters (FI2, FI3). The filtered signal is amplified at
the YGR amplifier (IC1, pins 1, 4) after passed through the
band switch (D2), attenuator (R5–R7) and bypass switches
(D7, D9).
The amplified signal is applied to the drive and power ampli-
fier circuits (PA unit) via J1.
3 - 5
• TRANSMITTER CONSTRUCTION
FI901
MIC
BPF
Ceramic
455 kHz
3rd LO
(438.85 kHz)
IC2201
IC551
IC551
IC301
Controller
A/D
DSP
ICs
D/A
FI601
BPF
Crystal
1st mixer
IC401
1st LO
(124.517−
594.487 MHz)
HPFs
BPF
IC504
LPFs
PA UNIT
LOGIC UNIT (DSP circuit)
MAIN UNIT
DRIVER
UNIT
ANT1
ANT2
Q301
Q302
Q401
Q501
145 MHz
430 MHz
HF/50 MHz
Q901
AMP.
Q801
AMP.
2nd mixer
D801
2nd LO
(124.032 MHz)
124.487 MHz
AMP. PA
PA
PA