Kenwood TS-440S Serivce Manual page 10

TS-440S
CIRCUIT DESCRIPTIO N
3 . Transmitter Circuit Descriptio n
IC4
MIC pPCI I58HZ
SS B
D
<M1C AMP
GAI N
PRO C
FSK IN
45 .05^ -
75 .05MH z
Q46
3SK73
Q10,1 I
3SK122 x2
Q13,14
3SKI22x 2
F I
MC F
Q44
2SC2459
IC 5
AN612
CFI
IC 6
AN612
CF 4
IST
MIX 9 .83MH z DB M
ssB
Q16
2SC253 8
LP F
Q I
2SC2075
02,3 Q4, 5
2SC2509x2 2SC2879x 2
LPF/ -
0
A .T
R X
Fig . 6 Transmitter circuit configuration
In SSB, CW, AM, or FSK mode, the transmitter system use s
triple conversion . In FM mode, the transmitter system use s
double conversion using PLL modulation .
Audio signals from the microphone are applied to the MI C
pin (connector (21)) of the IF unit and are separated into SS B
modulation and VOX signals . The SSB signal is amplified ap-
prox . 8 dB by IC4 (µ.PC 1 1 58HZ) . AFSK audio signals fro m
the AFSK IN pin (back panel) are also applied to IC4 .
IC4 functions as a SPEECH processor . Output from IC4 i s
distributed to the MIC GAIN control (front panel) and FM cir-
cuit (RF unit) . In SSB mode, the signal applied to the MI C
GAIN control is sent back to the IF unit (connector (23) MV2) ,
amplified by Q44 (2SC2459), and supplied to the balance d
modulator IC5 (AN612) . In FM or CW mode, Q44 does no t
operate because a cut-off voltage is supplied to its emitte r
via diodes D82 and D46 . The signal converted to 455 kH z
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