Icom ID-5100A, Руководство по обслуживанию

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4-4
MODULATION CIRCUITS (MAIN UNIT)
The MIC signal from the TX AF circuits is applied to the VCO
as the GMSK (For the DV mode) or Frequency Modulation
(For the FM mode) modulation signal.
VHF BAND
The modulation signal is applied to the VHF VCO (Q211,
D203, D204 and D228).
The modulated VCO output signal is amplifi ed by the buffer
(Q215) and LO AMP (IC203), and then applied to the TX AMP
circuits as the TX signal, through the LO SW (D50).
UHF BAND
The modulation signal is applied to the UHF VCO (Q232,
D223, D224 and D227) as a modulation signal.
The modulated VCO output signal is amplifi ed by the buffer
(Q235) and LO AMP (IC208), and then applied to the TX AMP
circuits as the TX signal, through the LO SW (D52).
TX AMP CIRCUITS (MAIN UNIT)
VHF BAND
The TX signal is passed through the LPF (L50, L51, C215,
C220 and C225) and ATT (R146, R147 and R151), and then
sequentially amplifi ed by the YGR (Q36), drive AMP (Q40)
and power AMP (IC3).
The amplifi ed TX signal is passed through the LPF (L67,
C291 and C297), TX output power detector (D59 and D63),
ANT SW (D66) and two LPFs (L90, L94, L96, C409, C418
and L79, L83, L87, C378, C386, C394), before being applied
to the antenna.
UHF BAND
The TX signal is passed through the HPF (L52 and C232) and
ATT (R155, R156 and R162), and then sequentially amplifi ed
by the YGR (Q38), drive AMP (Q41) and power AMP (IC4).
The amplifi ed TX signal is passed through the LPF (L69,
C310 and C319), TX output power detector (D62 and D67),
ANT SW (D68 and D84), HPF (L84, L88, C391, C395 and
C402) and LPF (L90, L94, L96, C409, C418), before being
applied to the antenna.
APC CIRCUITS (MAIN UNIT)
At the TX output power detector, the RF signal at the LPFs
(VHF band: L68, C301, C302 and C326/UHF band: L73,
C322, C323 and C350) is rectifi ed by the diodes (VHF band:
D59 and D63, UHF band: D62 and D67), and it is used as the
TX power sensing voltage.
The voltage is applied to the APC AMP (IC2), and the output
voltage controls the bias voltages of the power AMP (VHF
band: IC3, UHF band: IC4) to keep the TX output power con-
stant.
HPF LPF
PWR
AMP TX/RX
SW
LPF
TX/RX
SW AMP
LO
AMP
LO DRIVE
AMP
PWR
AMP
LPF
ANTENNA
BUFF
YGR ATT
LPF
DRIVE
AMP
HPF
TX/RX
SW
BUFF
YGR
ATT
APC
CTRL
PWR
DET
PWR
DET
LPF
TX/RX
SW
LPF HPF
118-550MHz
118-174MHz
375-550MHz
VCOMOD
MOD
MUTE
UHF band
VHF band
UHF TX VCO
VHF TX VCO
IC205
Q215
Q211
Q207
IC203
Q232
Q227
Q235
IC208
D52
D50
Q38 Q41 IC4 D62/D67 D68/D73/D75
Q36 Q40 IC3 D59/D63
D66/D69/
D70/D77
UHF RX circuit
VHF RX circuit
IC2
D84
• TX AMP AND APC CIRCUITS