3 - 5
RL252
RL253
D301/D302
TUNER_
CPU
TUNER_
NET
RL101
ATT
YGR
AMP
LPF-1
LPF-2
LPF-3
LPF-4
LPF-5
LPF-6
LPF-7
RL402
RL401
RL352
RL351
RL252
RL251
RL302
RL102
RL201
RL101
RL202
RL301
PHASE
DET
D21,22
L21
SW R
DET
D 1/D2
DRIVE
PRE
LPF
PWR
AM P
DRIVE
(PUSH-PULL)
RESIST
DET
RL151
RL152
ATT
LPF
AMP
AMP
AMP
FORV (FORWARD WAVE)
REFV (REFLECT WAVE)
CURRENT
DETECT
ANT1
ANT2
TUNER
UNIT
CTRL UNIT
1.8MHz
3.5M/3.8M/4.63MHz
5M/7MHz
18M/21MHz
24M/28MHz
50MHz
10M/14MHz
PA UNIT
FILTER UNIT
RF UNIT
D8
IC201
IC1
IC51
IC51
RL103
RX circuits
IC201
Q1
Q2,Q3
Q4,Q5
D41/D42
From TX circuits
• TX AMPLIFERS AND TX FILTER CIRCUITS
TX AMPLIFIER CIRCUITS (RF AND PA UNITS)
The TX signal from the BPF circuits is applied to the YGR
AMP (RF UNIT; IC201) via the attenuator. The amplifi ed TX
signal is applied to the PA UNIT via the LPF.
The TX signal from the RF UNIT is applied to the pre-drive
AMP (Q1) via the attenuator, and the amplifi ed TX signal is
applied to the drive AMP (Q2, 3) via the LPF. The amplifi ed
TX signal is then power-amplifi ed by the power AMP (Q4, 5).
The power-amplified TX signal is applied to the TX filter
circuits.
TX FILTER CIRCUITS
The power-amplifi ed TX signal from the PA UNIT is passed
through one of LPFs according to 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)
The TX signal from the FILTER UNIT is passed through
4 detection circuits on the CTRL UNIT before being fed to
the antenna connector [ANT1] or [ANT2].
Based on the parameters from these 4 detection circuits,
the tuner CPU (IC201) controls matching networks on the
TUNER UNIT to match the transceiver and connected
antenna.
SWR DETECTION CIRCUIT
The forward wave is rectified by D2 at the current detect
transformer (L1). The rectifi ed voltage is DC amplifi ed by IC1
and applied to the A/D port of the tuner CPU (IC201).
The reflected wave is rectified by D1 at the current detect
transformer (L1). The rectifi ed voltage is DC amplifi ed by IC1
and applied to the A/D port of the tuner CPU (IC201).
PHASE DETECTION CIRCUIT
The TX signal which is picked up at the current detect
transformer (L21) and the TX signal which is divided by C21,
C22 and C24, are rectifi ed by D21 and D22, and amplifi ed
by C-MOS IC (IC21).
The amplified signal is applied to the IC23 via the buffer
(IC22) for phase comparison. The resulting signal of phase
comparison is rectifi ed by D23 and D24, and composed and
amplifi ed by IC51, then applied to the A/D port of the tuner
CPU (IC201).
This AMP, as the fi rst stage, employs a C-MOS type AMP to
detect the low TX signal. The inverter AMP requires input level
lower than others need, and provides high speed operation
for stable high frequency operation with low TX signal.
RESISTANCE DETECTION CIRCUIT
A portion of the TX signal is divided by C42 and C44, and
rectifi ed by D42 to be converted into DC signal.
Another portion of the TX signal is rectified at the current
detect transformer (L41) to be converted into DC signal too.
And the voltage of these signals are the same when the
connected load (=antenna) is 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 amplifi ed by IC51
and applied to the A/D port of the tuner CPU (IC201).
CURRENT DETECTION CIRCUIT
A portion of the TX signal is rectifi ed by D81, L81 and R81,
and applied to IC81 to be level-compared with the voltage
from the SWR detection circuit.
When the connected load (=antenna) is less than 10
Ω
,
the TX signal is bypassed the TUNER UNIT via the tuner
switches (RL104 and RL105) compulsorily, to protect the
circuit on the TUNER UNIT from refl ected waves.