VHF ANT
UHF ANT
LPF
LPF
TX/RX
SW
D451-D454
TX/RX
SW
RL751
SWR
DET
D801
D811
SWR
DET
D501
D511
PWR
AMP
Q701
Q702
PWR
AMP
Q401
Q402
HPF
LPF
DRIVE
PRE
Q201
YGR
AMP
Q171
DRIVE
AMP
Q251
AMP
Q151
From
YGR AMP
PA-B UNIT
3 - 7
HF TX AMPLIFIER CIRCUITS (PA-A UNIT)
The TX signal from the BPF UNIT is sequentially amplifi ed
by the pre-drive AMP (Q201), drive AMP (Q221, Q222), and
power AMP (Q241, Q242).
The amplifi ed TX signal is applied to the TX fi lter circuits.
TX FILTER CIRCUITS (PA-A UNIT) (For only HF band)
The amplified TX signal from the power AMP (Q241,
Q242) is passed through one of LPFs, depending on the
transmitting frequency, to remove harmonic components
contained in the TX signal.
The fi ltered TX signal is applied to the CTRL UNIT.
ANTENNA TUNING AND SWITCHING CIRCUITS
(CTRL UNIT) (For only HF band)
The TX signal from the PA-A UNIT is passed through
4 detection circuits on the CTRL UNIT, before being applied
to the antenna connector [ANT1] or [ANT2].
Refering to the detected parameters, the tuner CPU (IC701)
controls the tuning networks on the NETWORK UNIT, to
match the transceiver and connected antenna.
SWR DETECTION CIRCUIT
The forward wave is rectified by D12 at the current detect
transformer (L11). The rectified voltage is amplified by the
DC AMP (IC41), and then applied to the A/D port of the
tuner CPU (IC701).
The refl ected wave is rectifi ed by D11 at the current detect
transformer (L11). The rectified voltage is amplified by the
DC AMP (IC41), and then applied to the A/D port of the
tuner CPU (IC701).
REACTANCE DETECTION CIRCUIT
The TX signal which is picked up at the current detect
transformer (L101), and the TX signal which is picked up by
C101, C105 and R105, are rectifi ed by D102 and D101, and
amplifi ed by C-MOS IC (IC111).
VHF/UHF TX AMPLIFIER CIRCUITS (PA-B UNIT)
• VHF BAND
The TX signal from the RF-B UNIT is sequentially amplifi ed
by the AMP (Q151), YGR AMP (Q171), pre-drive AMP
(Q201), drive AMP (Q251), and then applied to the power
AMP (Q701, Q702).
The amplified TX signal is passed through the TX/RX
SW (RL751), LPF(L771–L773, C771–C777) and SWR
detecter (D801, D811), before being applied to the antenna
connector [144MHz ANT].
• UHF BAND (PA-B UNIT)
The TX signal from the RF-B
UNIT is sequentially amplified by the AMP (Q151), YGR
AMP (Q171), pre-drive AMP (Q201), drive AMP (Q251), and
then applied to the power AMP (Q401, Q402).
The amplified TX signal is passed through the TX/RX SW
(D471–D473), LPF(L451, L452, C451–C455) and SWR
detecter (D501, D511), before being applied to the antenna
connector [430MHz ANT].
AMP
IC31
AMP
IC171
AMP
IC171
CURRENT
DET
D401
TUNING
NETWORK
AMP
IC431
SWR
DET
D11/D12
RESIST
DET
D151
D152
PHASE
DET
HF ANT1
HF ANT2
DRIVE
AMP
Q221/Q222
DRIVE
PRE
Q201
RL902
RL901
LPF
PWR
AMP
Q241/Q242
LPF
RL501
RL702
RL1001
LPF
RL802
LPF
RL601
RL1102
LPF
RL701
RL602
RL1101
LPF
RL801
RL502
LPF
RL1002
From the
BPF circuits
D251
CPU
RL301
CTRL UNIT
P
TUNER
R
RL501
FOR/REF
IC701
RL351
ANTI
5/7 MHz
3.5/3.8/4.63 MHz
10/14 MHz
24/28 MHz
50 MHz
18/21 MHz
PA-A UNIT
1.8 MHz
NETWORK
UNIT
The amplifi ed signal is applied to IC131, through the buffer (IC121)
for phase comparison. The resulting signal of phase comparison
is rectifi ed by D131 and D132, and composed and amplifi ed by
IC51, then applied to the A/D port of the tuner CPU (IC171).
RESISTANCE DETECTION CIRCUIT
A portion of the TX signal is picked up by L151 and C152,
and rectifi ed by D152 to be converted into DC voltage.
Another portion of the TX signal is rectifi ed by D151 to be
converted into DC voltage too.
And these voltages are the same when the connected load
(=antenna) is matched to 50
Ω
. Thus the difference of these
voltages represents the resistance components.
By compar ing the difference of these voltages, the
transceiver detects the resistance components.
The detected resistance components are buffered by Q151
and amplifi ed by IC171, and then applied to the A/D port of
the tuner CPU (IC701).
CURRENT DETECTION CIRCUIT
A portion of the TX signal is picked up by L401, rectifi ed by
D401, and applied to IC431 to be level-compared with the
voltage from the SWR detection circuit.
When the resistance of connected load (=antenna) is less than
10
Ω
, the TX signal is bypassed the NETWORK UNIT, through
the tuner compulsorily switches (RL301 and RL351), to protect
the circuit on the NETWORK UNIT from refl ected waves.
• HF TX AMPLIFIER AND FILTER CIRCUITS
• VHF/UHF TX AMPLIFIER CIRCUITS
