Tx Amplifier Circuit (Main And Pa Units) - Icom IC-7100 Service Manual

TX AMPLIFIER CIRCUIT (MAIN AND PA UNITS)

The TX signal from the band fi lter circuit is applied to the
YGR AMP (IC3021), through the 3 dB attenuator (R3022 to
R3024).
The amplifi ed signal is passed through the 72 MHz LPF
(L3014, C3015 to C3017), or the 124 MHz HPF (L3012,
L3013, C3012 to C3014). The fi ltered signal is passed
through two attenuators (3 dB: R3011 to R3013 and 6 dB:
R101 to R103), and then sequentially amplifi ed by the RF
AMP (Q101), pre-drive AMP (Q102) and drive AMP (Q251).
• While operating on the HF, 50 MHz and 70 MHz bands
The amplifi ed signal is applied to the power AMP (Q301
and Q302), through the diplexer (L411, C413, C513, C514,
C515). The amplifi ed signal is passed through the TX/RX SW
(RL801) and one of the LPFs, depending on the operating
band, to remove harmonic components.
The fi ltered signal is applied to the antenna connector
([ANT1]: J1) through the power and SWR detect circuit (D961
and D962).
• TX AMPLIFIER CIRCUIT
3dB
ATT
IC3021
From the 1st TX IF circuit
3dB YGR
AT T
AMP
HF/50MHz/70MHz BAND ->
Q101
Q251
Q102
RF PRE
DRIVE
DRIVE DIPLEXER
AMP
AM P
6dB
ATT
fc=72MHz
LP F
fc=124MHz
HPF
• While operating on the 144 MHz and 430 MHz bands
The amplifi ed signal is applied to the power AMP (Q501),
through the diplexer (L203, L204, C214, C216, C262, C266).
The amplifi ed signal is passed through another diplexer
(L411, C413, C513, C514, C515), which separates the band
signal.
- 144 MHz band signal
The TX signal is passed through the TX/RX SW (RL531) and
LPF (L541 to L543, C542 to C547).
- 430 MHz band signal
The TX signal is sequentially passed through the TX mute
SW (D431 and D432), TX/RX SW (D422 to D424), another
mute SW (D433 and D434) and HPF (L441, L442, C441 to
C444).
The fi ltered 144 MHz/430 MHz band signal is applied to the
antenna connector ([ANT2]: J2), through the LPF (L591 to
L593, C591 and C592), which removes harmonic compo-
nents, and the SWR detect circuit (D651 and D661).
Q301,Q302
PWR
AMP
TX/RX
SW
To the RX circuit
PA UNIT
430 MHz BAND ->
D431,D432
Q501
D422 to D424
MUTE
PWR
TX/RX
DIPLEXER
AMP
SW
To the
RX circuit
TX/RX
SW
To the
RX circuit
144 MHz BAND ->
3-7
0.03-2.0MHz D961,D962
PWR/SWR
LPF
DET
2.0-4.0MHz
LPF
4.0-7.3MHz
LPF
7.3-14.35MHz
LPF
14.35-21.45MHz
LPF
21.45-33.0MHz
LPF
33.0-74.8MHz
LPF
D651,D661
D433,D434
fc=270M fc=700M
PWR/SWR
HPF LPF
MUTE
fc=200M
LPF
HF/50MHz/70MHz
ANTENNA
144/430MHz
ANTENNA
DET