Transmission Signal Path; Receive Signal Path - Kenwood TS-990S Service Manual

CN665
CN670
CN50
Int. Speaker
J50
Ext. Speaker1
J51
Ext. Speaker2
K52
Headphone AMP
PMUTE
CN667
Headphone
Headphone AMP
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).
CIRCUIT DESCRIPTION
IC675(A/2)
Active LPF
MRIF/MFMD
IC675(B/2)
Inverter
IC678(B/2)
Active LPF
SRIF/SFMD
IC678(A/2)
Inverter
IC660
IC51
(A/2)
K50 AF Power
AMP Active LPF
AF Mute
SMUTE1
IC52
K51
AF Power
AMP
AF Mute
SMUTE2 IC661
(A/2)
IC50(1/2)
IC671(A/2)
Active LPF
Buffer
IC50(2/2) IC671(B/2)
Buffer
Fig. 37 Receive signal path
IC667(A/2)
Active LPF
IC398
ADC
L+/-
IC667(B/2)
Active LPF
IC670(B/2)
Active LPF
IC392
ADC
L+/-
IC670(A/2)
Active LPF
IC665(A/2)
E-VOL
IC660
IC673(A/2)
(-3 ~ -95dB)
Addtion
(B/2)
IC665(B/2)
E-VOL
(-3 ~ -95dB)
IC661
(B/2)
IC673(B/2)
IC664(A/2)
Addtion
E-VOL
(-3 ~ -95dB)
IC664(B/2)
E-VOL
(-3 ~ -95dB)
IC683(1/2)
IC674(2/2)
CN668
Buffer
Active LPF
MIC
MSG
IC683(2/2)
Buffer
MODSEL
Q655
CN666
Q654
FMOD
TIF
CN663
Fig. 38 Transmission signal path
TS-990S
IC202
TXMRX-
DSP
IC385
DAC
Lch
IC390
IC300 DAC
SRX-DSP L+/-
R+/-
IC650(A/2)
Active LPF
IC650(B/2)
Active LPF
IC652(A/2)
Active LPF
IC666(B/2)
Active LPF
IC398
ADC
R+/-
IC674(1/2) IC666(A/2)
Inverter Active LPF
Active LPF
IC686(2/2)
Analog SW IC679 IC668 IC668
(B/2) (B/2) (A/2)
IC686(1/2)
Analog SW
IC202
TXMRX-
DSP
IC397
DAC
Lch
33