TS-5700
C I R C U IT D ES CR I PTI O N
Transmitter Circuit Configuration
Figure 9 is a block diagram of the transmitter circuit.
The audio signal from the microphone is AF-pro
cessed by the DSP in the control unit and enters CN15
(pin
4:
MOD/ANO) of the TX-RX unit. The signal is split
and directed to the SSB/AM and FM systems by IC12:
BU4066BCFV.
In the SSB system, the signal is amplified by 036
(2SC2712K(S)), balance-modulated with the CAR sig
nal (8.83MHz) input from CN12 by IC2 (µPC1037GR),
passes through 038 (2SC2412K(S)), and enters the
crystal filter. The SSB signal passing through the filter
is amplified by 029 (3SK131 M). It is mixed with the
L02 signal (64.22MHz) from CN5 by 027 and 030 to
produce a 73.05MHz signal. It is then mixed with the
L01 signal (78.08 to 103.05MHz) from CN2 by 028,
031 (3SK184(R)) to generate the desired signal. The
signal passes through a band-pass filter, is amplified
by 035 (2SC2954) to produce the drive output, which
is output from CN10 and goes to CN1 of the final unit.
The signal is amplified to 1 OOW by 01 to 05. Har
monic components are attenuated by a low-pass filter.
The signal passes through the forward/reflected wave
detection circuit, AT voltage/current detection circuit
transmit/receive change relay K2, AT I N /TH R
U
changeover relay K1, ANT 1/2 changeover relay K3,
and is directed to the antenna connector.
In the AM mode, the signal is generated by break
ing the balance of the carrier of SSB balance modula
tor IC2: µPC1037GR, and output through the same
route as the SSB.
In the FM mode, the audio signal from the micro
phone connector is pre-emphasized and !DC-pro
cessed by the DSP in the control unit and goes to the
TX-RX unit. The signal is separated from the SSB/AM
system by IC12: BU4066BCFV, passes through W5,
and enters the PLL unit to modulate L02 (64.22MHz).
In the CW mode, the key input signal goes to IC5 in
the control unit. The CKY signal output from IC6
switches 024 and 021 in the TX-RX unit to generate
the CW signal.
•
ALC Circu it
The forward wave voltage (VSF) detected by the fi
nal unit is changed by a resister and goes to the differ
ential amplifier comprised of 01 and 02. When the
VSF rises, the base voltage of 01 rises, so the emitter
voltage of 01 and 02 increases and the current flow
ing through the base of 02 decreases, and thus the
collector voltage of 02 rises. When this voltage ex
ceeds VBE + VE (about 2.4V) of 03, the base current
flows and the collector voltage to which ALC time con
stants C and R are connected drops.
The collector voltage change is shifted by 04 and
D2 and matched with the voltage for keying by 05 and
D3 to generate the ALC voltage. This ALC voltage
lowers the second gate voltage of 029 (3SK131 (M)) of
the TX-RX unit to activate the ALC.
In AM transmission, 079 turns on and the ALC volt
age is controlled by the average power. The reference
voltage, VREF, for the ALC is set by the adjusted value
from the microcomputer and output from IC6.
IC 1 6 : KCC 1 1
r----------------------------
Fig.
10
ALC, Power control,
SWR
protection circuits
1 3
