Kenwood TS-990S Service Manual

TS-990S
33
CIRCUIT DESCRIPTION
8-4. Transmission Signal Path (MIC Input to the IF
Signal/FM Transmission AF output)
The signal input from the microphone is sent to the MIC
connector (CN668) and is applide to the differential ampli-
fi er (IC683). The output signal from the differential amplifi er
is applied to the R channel of the ADC (IC398) through the
active fi lters (IC674 and IC666). The TXMRX-DSP (IC202)
processes the MIC signal sampled by the ADC at an fs of
96kHz, and the signal is sent from the L channel of the DAC
(IC397) at an fs of 96kHz. The signal output from the DAC
passes through the active fi lters (IC668 and IC679) and is
applide to the analog switcher (IC686), when the output des-
tination will be changed.
In the case of transmission in FM mode, the signal is sent
from CN666 and input into the PLL (SUB LO) unit (X50-323
CN66). In the case of transmission in modes other than FM
mode, the signal is sent from CN663 and input into the TX-RX
unit (X57-827 A/2 CN700).
Fig. 37 Receive signal path
Fig. 38 Transmission signal path
CN668
IC398
ADC
R+/-
IC202
TXMRX-
DSP
IC397
DAC
Lch
IC683(1/2)
Buffer
IC683(2/2)
Buffer
IC674(2/2)
Active LPF
IC666(B/2)
Active LPF
IC666(A/2)
Active LPF
IC674(1/2)
Inverter
MODSEL
IC668
(A/2)
IC668
(B/2)
IC679
(B/2)
Active LPF
IC686(2/2)
Analog SW
IC686(1/2)
Analog SW
Q655
Q654
MIC
MSG
CN666
CN663
FMOD
TIF
CN665
IC398
ADC
L+/-
CN670
IC392
ADC
L+/-
IC202
TXMRX-
DSP
IC300
SRX-DSP
IC390
DAC
L+/-
R+/-
IC675(A/2)
Active LPF
IC667(A/2)
Active LPF
IC675(B/2)
Inverter
IC667(B/2)
Active LPF
IC678(B/2)
Active LPF
IC678(A/2)
Inverter
IC670(B/2)
Active LPF
IC670(A/2)
Active LPF
IC650(A/2)
IC650(B/2)
IC660
(A/2)
IC660
(B/2)
IC661
(B/2)
IC661
(A/2)
Active LPF
Active LPF
IC665(A/2)
E-VOL
IC665(B/2)
E-VOL
IC664(B/2)
E-VOL
IC664(A/2)
E-VOL
IC673(A/2)
Addtion
IC673(B/2)
Addtion
IC52
AF Power
AMP
IC51
AF Power
AMP
K50
AF Mute
SMUTE1
SMUTE2
K51
AF Mute
Ext. Speaker1
J50
J51
Ext. Speaker2
CN50
Int. Speaker
IC50(1/2)
Headphone
AMP
IC50(2/2)
Headphone
AMP
PMUTE
CN667
Headphone
MRIF/MFMD
SRIF/SFMD
IC385
DAC
Lch
IC652(A/2)
Active LPF
(-3 ~ -95dB)
(-3 ~ -95dB)
(-3 ~ -95dB)
(-3 ~ -95dB)
Active LPF
Active LPF
IC671(B/2)
Buffer
IC671(A/2)
Buffer
K52

Kenwood TS-990S Specifications

General

Receiver Type	Triple Conversion Superheterodyne
Antenna Tuner	Built-in automatic antenna tuner
DSP	Yes
IF DSP	Yes
Modes	SSB, CW, AM, FM
Display	7-inch TFT color LCD
Weight	25 kg (55.1 lbs)
Antenna Connectors	SO-239
Power Supply	13.8V DC