Kenwood TS-990S Service Manual

TS-990S
42
COMPONENTS DESCRIPTION
Ref. No. Use/Function Operation/Condition/Compatibility
D100
Back electromo-
tive force protec-
tion
For L101
D120
Back electromo-
tive force protec-
tion
For L121
D140
Back electromo-
tive force protec-
tion
For L141
D220 ~ 222 Surge protection For 10MHz reference receptacle
D223,244
Reverse current
prevention
EL-KEY

(PADDLE) prevention
D225,226 Surge protection For EXT AT terminal
D230 Surge protection For EXT AT terminal
D270,271 Rectifi er For -12V power supply
D805
Back electromo-
tive force protec-
tion
For L808
D807
Back electromo-
tive force protec-
tion
For L811
Final unit (X45-3880-00)
Ref. No. Use/Function Operation/Condition/Compatibility
IC1 D/A convertor
Ao1: “H” when drive output power
is too high
Ao2: Reserved
Ao3: Reserved
Ao4: Reserved
Ao5: Reserved
Ao6: Reserved
Ao7: Reserved
Ao8: Reserved
IC3 OP amplifi er RF power control
IC5
Drain current
detection
Current detection
IC6 Shift register
Q1: 50L “H” when
49.0~54.0MHz LPF is selected
Q2: “H” when 50M and 28M band
are selected
Q3:L “H” when FINAL fan ro-
tates at low speed
Q4:M “H” when FINAL fan
rotates at mid speed
Q5:H “H” when FINAL fan
rotates at high speed
Q6: “H” when AT fan rotates at
low speed.
Q7: “H” when AT fan rotates at
high speed
Q8: 5M “H” when AT becomes
ON at 5MHz band
IC7 Shift register
Q1: 2L “H” when 1.705~2.1MHz
band LPF is selected
Q2: 7L “H” when 5.5~7.5MHz
band LPF is selected
Ref. No. Use/Function Operation/Condition/Compatibility
IC7 Shift register
Q3: 14L “H” when
10.5~14.5MHz band LPF is se-
lected
Q4: 3L “H” when 2.1~4.0MHz
band LPF is selected
Q5: 28L “H” when
21.5~30.0MHz band LPF is se-
lected
Q6: 10L “H” when 7.5~10.5MHz
band LPF is selected
Q7: 21L “H” when
14.5~21.5MHz band LPF is se-
lected
Q8: 5L “H” when 4.0~5.5MHz
band LPF is selected
IC8 OP amplifi er Current protection
IC800 Shift register
Q1: ANT1 “H” when ANT1 is
selected during transmission
Q2: ANT2 “H” when ANT2 is
selected during transmission
Q3: ANT3 “H” when ANT3 is
selected during transmission
Q4: ANT4 “H” when ANT4 is
selected during transmission
Q5: SANT1 “H” when ANT1 is
selected during reception
Q6: SANT2 “H” when ANT2 is
selected during reception
Q7: SANT3 “H” when ANT3 is
selected during reception
Q8: SANT4 “H” when ANT4 is
selected during reception
Q2
Pre-drive ampli-
fi e r
HF band amplifi er
Q3 Drive amplifi er HF band amplifi er
Q4 Switching ON when RX
Q5,6 Switching Over drive protection
Q7(A/2,B/2) Final amplifi er HF band amplifi er
Q9 Switching
ON when FINAL fan rotates at
high speed
Q10 Switching
ON when FINAL fan rotates at
mid speed
Q11 Switching
ON when FINAL fan rotates at
high speed
Q12 Switching
ON when FINAL fan rotates at
mid speed
Q13 Switching
ON when FINAL fan rotates at
low speed
Q14 Switching
ON when FINAL fan rotates at
low speed
Q15 Switching
ON when 49.0~54.0MHz band
LPF is selected
Q16 Switching
ON when 2.1~4.0MHz band LPF
is selected
Q17 Switching
ON when 5.5~7.5MHz band LPF
is selected
Q18 Switching
ON when 10.5~14.5MHz band
LPF is selected

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