TS-5700
CIRCU IT D ES CRI PTI O N
D D S 1 (CAR)
Component
L S B
U S B
cw
CW-R
FSK
FSK-R
AM
FM
RX
TX
RX
TX
RX
TX
RX
TX
RX
TX
RX
TX
RX
TX
RX
TX
BASE
1 . 1 7 M H z (AM RX, F M RX : O F F)
Offset
WIDE (24k)
+ 1 . 5 k + 1 . 5 k
-1 . 5k -1 .5k -0 . 7 k
-0 . 7 k
+ 0 . 7 k
+ 0 . 7 k
+ 8 5
+ 8 5
-85
-85
O F F
0
O F F
0
NAR ( 1 800)
+ 1 . 5 k
+ 1 . 5 k
-1 . 5k
-1 . 5k -0.4k
-04k
+ 0 . 4 k
+ 0 . 4 k +85
+85
-85
-85
O F F
0
O F F
0
NAR
1500/270)
+ 1 . 5 k
+ 1 . 5 k
- 1 .5k
-1 .5k
0
0
0
0
+85
+85
-85
-85
O F F
0
O F F
0
CW pitch
-
-
-
-
-(PITCH)
-
+(PITCH)
-
-
-
-
-
-
-
-
-
FSK tone ( H )
-
-
-
-
-
-
-
-
+2.125k
-
-2.125k
-
-
-
-
-
(FSK-SI
FSK to n e ( L)
-
-
-
-
-
-
-
-
+ 1.445k
-
-1.445k
-
-
-
-
-
IFSK-S)
FSK s h ift IM)
-
-
-
-
-
-
-
-
-
0
-
0
-
-
-
-
FSK s h ift (S)
-
-
-
-
-
-
-
-
-
-
-IFSK-SI
-
-
-
-
R IT/XIT
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
CAR s u ppression
+!CAR LI
+(CAR LI
-(CAR U)
-!CAR UI
-
-
-
-
-
-
-
-
-
-
-
-
IF s h ift
+ll F SI
-
-(IF S)
-
-( I F S)
-
+ll F SI
-
+ (IF Si
-
-(IF S)
-
-
-
-
-
Table 3 DDS1 (CAR) freq uency config u ration
Receiver Circu it Config u ration
Figure 5 is a block diagram of the receiver circuit.
The receiver utilizes double conversion with the
first IF of 73.05MHz and the second IF of 8.83MHz
(triple conversion in FM with the third IF of 455kHz).
The signal coming from the antenna connector
passes through the ANT1/ANT2 switching relay, ATIN/
THRU switching relay, transmit/receive relay and im
age filter, and goes to the TX-RX unit. The signal
passes through the about-20dB attenuator and IF trap
low-pass filter and goes to the 10-part band-pass filter
(low-pass filter if the frequency is lower than 1.7MHz).
If the frequency is 1.7MHz or higher, the signal passes
through a high-pass filter and then a band-pass filter to
reduce interference of a strong medium wave output
station.
If PRE-AMP is ON, the signal passing through each
band-pass filter passes through the low-band and
high-band pre-amplifiers. The low-band (21.5MHz or
lower) pre-amplifier is a parallel amplifier 017, 018:
2SK520x2 with N FB. The high-band (21.5MHz or
higher) pre-amplifier is a dual-gate MOS FET 025:
3SK131 to provide the optimum characteristics for
each band. If PRE-AMP is OFF, the pre-amplifiers are
bypassed and the dynamic range is boosted.
The signal then passes through the IF trap low-pass
filter and is mixed with LO 1 by the first mixer 05 to
08: 2SK520x4 to produce the first IF of 73.05MHz.
The resulting signal passes through two MCFs (XF1)
and AGC amplifier 012: 3SK131, and is mixed with
L02 (64.22MHz) by the second mixer 010, 013:
2SK520x2 to produce the second IF of 8.83MHz. The
second IF signal output from the mixer is divided into
two signals: one passes through the buffer amplifier
and goes to the NB amplifier. The other signal enters
the IF amplifier 011: 3SK131. The AGC is controlled
and noise is blanked by the NB in 011.
The second IF signal passes through the 8.83MHz
IF filter. One of THRU, 6kHz, 2.4kHz, and optional
bandwidth frequency (1 .SkHz, 500Hz, or 270Hz) can
be selected for the IF filter.
The signal is then amplified by 014: 2SC2412K and
goes to the FM detection HIC IC7: KCD10 and SSB/
AM/CW detection HIC IC15: KCD11. In FM mode, the
signal is converted to the third IF of 455kHz by KCD10,
passes through the limiter amplifier, and quadrature
detected. In modes other than FM, the signal is ampli
fied by KCD11 and used for the AGC voltage. In SSB
and CW, the signal is product-detected and in AM, en
velope-detected and output. Each detection output is
selected by IC9: BU4066BCFV for each mode and
goes to the control unit.
In the control unit, the signal is amplified by IC503:
NJM21 OOM, goes to CODEC IC IC504: AK4506-VS to
convert it to a digital signal. The resulting signal is fil
tered by DSP IC507: ADSP2181 KS-115, the volume is
controlled, and the subtone is decoded. The signal is
converted to an analog signal by the CODEC IC,
pa s s e s t h r o u g h a c t i v e f i l t e r IC505, IC506:
NJM21 OOM, returns to the TX-RX unit, and amplified
to the required level by AF amplifier IC8: LA4446.
7
