This service manual describes the latest technical
information for the ID-880H and ID-E880 VHF/UHF DIGITAL
TRANSCEIVER at the time of publication.
MODEL VERSION
[TPE]
[USA]
ID-880H
ID-E880
[KOR]
[AUS]
[CHN]
[EXP]
[EUR]
[ITR]
[EUR-01]
TYPE OF
EMISSION
F2D, F3E,
F7W
Max. TX POWER
(VHF/UHF)
25/25
50/50
NEVER connect the transceiver to an AC outlet or to a DC
power supply that uses more than specified. This will ruin
the transceiver.
DO NOT expose the transceiver to rain, snow or any liquids.
DO NOT reverse the polarities of the power supply when
connecting the transceiver.
DO NOT apply an RF signal of more than 20 dBm (100 mW) to
the antenna connector. This could damage the transceiver’s
front-end.
To upgrade quality, any electrical or mechanical parts and
internal circuits are subject to change without notice or
obligation.
ORDERING PARTS
Be sure to include the following four points when ordering
replacement parts:
1. 10-digit Icom parts numbers
2. Component name
3. Equipment model name and unit name
4. Quantity required
<ORDER EXAMPLE>
1110003491 S.ID TA31136FNG ID-880E/ID-880H MAIN UNIT 5 pieces
8820001210 Screw 2438 screw ID-880H/ID-E880 Top cover 10 pieces
Addresses are provided on the inside back cover for your
convenience.
(ID-880H)
REPAIR NOTES
1. Make sure that the problem is internal before
disassembling the transceiver.
2. DO NOT open the transceiver until the transceiver is
disconnected from its power source.
3. DO NOT force any of the variable components. Turn
them slowly and smoothly.
4. DO NOT short any circuits or electronic parts. An
insulated tuning tool MUST be used for all adjustments.
5. DO NOT keep power ON for a long time when the
transceiver is defective.
6. DO NOT transmit power into a Standard Signal
Generator or a Sweep Generator.
7. ALWAYS connect a 50 dB to 60 dB attenuator between
the transceiver and a Deviation Meter or Spectrum
Analyzer when using such test equipment.
8. READ the instructions of test equipment throughly
before connecting a test equipment to the transceiver.
Icom, Icom Inc. and IDOM logo are registered trademarks of Icom Incorporated (Japan) in the United States, the United
Kingdom, Germany, France, Spain, Russia and/or other countries.
1) Unscrew total of 18 screws; 4 screws from the top cover,
8 screws from the both sides and 4 screws from the
bottom cover.
2) Remove the top cover and bottom cover as illustrated
below.
Top cover
Bottom cover
2. REMOVING THE MAIN UNIT (continued)
3) Unscrew 10 screws from the MAIN UNIT.
4) Unscrew 4 screws from the chassis.
5) Disconnect the cooling fan cable from the MAIN UNIT.
6) Unsolder total of 4 points, and take off the MAIN UNIT.
UNSOLDER
COOLING
FAN CABLE
Solder
remover
MAIN UNIT
Screw x4
Screw x10
<Bottom view>
2. REMOVING THE MAIN UNIT
1) Remove the IC clip from the chassis.
2) Disconnect the speaker cable from the MAIN UNIT, and
remove the speaker from the chassis.
SPEAKER
CABLE
IC clip
Speaker
3. DISASSEMBLE THE CONTROL UNIT
1) Remove 3 knobs from the front panel.
Knobs
2) Unscrew 4 screws from the rear panel.
3) Remove the LCD plate.
4) Take off the CONTROL UNIT from the front panel.
Rear panel
CONTROL UNIT
Front panel
Screw x4
LCD plate
<Top view>
(Continued to right above.)
Front panel
3 - 1
SECTION 4. CIRCUIT DESCRIPTION
4-1 RECEIVE CIRCUITS
RF CIRCUITS
144 MHz BAND (118–174 MHz)
The RX signals (118–174 MHz) from the antenna are
passed through two LPFs and TX/RX SW for VHF band (D59,
68, 75, 77), and applied to the RF circuit.
The RX signals are passed through the limiter (D78, 79) and
BPF, and amplifi ed by the RF AMP (Q33). The amplifi ed RX
signals are filtered by tuned BPF (D41, 44, 60) to remove
unwanted signals, then applied to the 1st mixer (Q124).
The passband frequency of the tuned BPF (D41, 44, 60) is
tuned by the tuning voltage from the D/A converter controlled
by the CPU (IC25).
300 MHz BAND (230–420 MHz)
The RX signals (230–420 MHz) from the antenna are
passed through the LPF, HPF and TX/RX SW for UHF band
(D30, 53, 61, 62, 177), and applied to the RF circuit.
The RX signals are passed through the RX SW (D56) and
filtered by the tuned BPF (D57, 58) to remove unwanted
signals, then applied to the RF AMP (Q35).
The amplifi ed RX signals are fi ltered by another tuned BPF
(D45, 51) to remove unwanted signals, and amplified by
another RF AMP (Q34). The RF AMP (Q34) improves the
isolation between the 1st mixer (IC64) and the tuned BPF.
The amplifi ed RX signals are applied to the 1st mixer (IC64).
The pass-band frequencies of the tuned BPFs (D57, 58:
D45, 51) are tuned by the tuning voltage from the D/A
converter controlled by the CPU (IC25).
800 M Hz BAND (810–999 MHz)
The RX signals (810–999 MHz) from the antenna are
passed through the HPF, and applied to the RF AMP (Q28).
The amplifi ed RX signals are fi ltered by the tuned BPF (D18,
20) to remove unwanted signals, then applied to the 1st
mixer (IC64) via the RX SW (D9).
The pass-band frequency of tuned BPF (D18, 20) is tuned
by the tuning voltage from the D/A converter controlled by
the CPU (IC25).
• RF CIRCUITS
D59,68,75,77
RF
AMP
TX/RX
SW
D41,D44,D60
BPF
BPF1,2,3
D12,14,23
BPF
BPF1,2,3
D45,D51
BPF
BPF2,3
D30,53,61,62,177
TX/RX
SW
Q33
RF
AMP
Q19
RF
AMP
Q35
RF
AMP
BPF
D13
BPF
BPF1
D57,58
BPF
BPF1
LPF
HPF
UHFLPF
VHFLPF
D78,D79
LIMITER
<- 118-174 MHz
D16
RX
SW
<- 420-550 MHz
D56
RX
SW
<- 230-420 MHz
LPF
From VHF TX circuit
From UHF TX circuit
To the 1st IF mixer (Q124)
To the 1st IF mixer (Q125)
<- To the 1st IF mixer (IC64)
D36
Q34
RX
SW
440 MHz BAND (420–550 MHz)
The RX signals (420–550 MHz) from the antenna are
passed through the LPF, HPF and TX/RX SW for UHF band
(D30, 53, 61, 62, 177), and applied to the RF circuit.
The RX signals are passed through the RX SW (D16) and
tuned BPF (D13) to remove unwanted signals, and applied
to the RF AMP (Q19). The amplifi ed RX signals are fi ltered
by another tuned BPF (D12, 14, 23) to remove unwanted
signals, then applied to the 1st mixer (Q125).
The pass-band frequencies of tuned BPFs (D13: D12,
14, 23) are controlled by the tuning voltage from the D/A
converter controlled by the CPU (IC25).
<- To the 1st IF mixer (IC64)
D9
RX
SW
D18,D20
BPF
BPF2,3
Q28
RF
AMP
HPF
<- 810-999 MHz
4 - 1
1st IF CIRCUITS
144 MHz BAND (118–174 MHz)
The RX signals (118–174 MHz) from the RF circuit are
applied to the G1 terminal of Q124 (1st IF mixer), and the
1st LO signals "140_LO" are applied to the G2 terminal of it.
2nd IF AND DEMODULATOR (for FM and AM) CIRCUITS
The 1st IF signal from the 1st IF circuits is applied to the
IF IC (IC15, pin 20). IC15 contains 2nd mixer, limiter AMP,
noise AMP, quadrature detector, RSSI circuit and AM
detector in its package.
These input signals are mixed to be converted into the
46.350 MHz 1st IF signal.
300 MHz (230–420 MHz) AND 800 MHz (810–999 MHz) BANDS
The RX signals (230–420 MHz and 810–999 MHz) from the
RF circuit are applied to the RX input terminal of IC64 (1st IF
mixer), and the 1st LO signals "UHF_LO" are applied to the
LO input terminal of it.
These input signals are mixed to be converted into the
46.350 MHz 1st IF signal.
440MHz BAND (420–550MHz)
The RX signals (420–550MHz) from the RF circuit are
applied to the G1 terminal of Q125 (1st IF mixer), and the
1st LO signals "440_LO" are applied to the G2 terminal of it.
These input signals are mixed to be converted into the
46.350 MHz 1st IF signal.
The 1st IF signal converted by the 1st mixer is passed
through the 1st IF fi lter (FI6) to remove unwanted signals.
FI6 is a 4-pole crystal filter contains two filters, and has
adequate selectivity to extract wanted signal.
The applied 1st IF signal is converted into the 450 kHz 2nd
IF signal by being mixed with tripled reference frequency
signal (45.9 MHz) from the PLL IC (IC14) via the tripler (Q52).
The converted 2nd IF signal is output from pin 3, and passed
through the ceramic fi lter (FI1 for FM narrow and AM modes,
FI2 for FM and DV modes) to remove sideband noise, then
applied to the IF IC (from pin 7; FM/DV mode/ from pin 5; AM
mode) again.
• 2ND IF CIRCUITS
450 kHz 2nd IF filter
FI1
PLL
IC
Q52
X3
45.9 MHz
2nd LO
Pin 11(FM/DV mode)
Pin 14(AM mode)
FI2
(For wide)
CERAMIC
BPF
WIDE/NARROW
(For narrow)
SELECTOR
IF IC
CERAMIC
BPF
X2
IC15
From the 1st IF circuits
X5
To the AF filter circuits
(FM/AM mode)
To the digital demodulator circuits
(DV mode)
TCXO
15.3 MHz
IC13
DETECT
SIGNAL
SELECTOR
IC14
The fi ltered 1st IF signal is applied to the 1st IF AMP (Q66)
via the limiter (D1009), and the amplified 1st IF signal is
applied to the IF IC (IC15) via another limiter (D88).
• 1ST IF CIRCUITS
From the 140 MHz band
Q124
RF circuit
140_LO
From the 440 MHz band
Q125
RF circuit
To the 2nd IF
circuits
D88
LIMIT
Q66
IF
AMPBPF
D1009
LIMIT
FI6
XTAL
46.35MHz
440_LO
From the 300 MHz and
IC64
800 MHz bands RF circuit
UHF_LO
4 - 2
FM DEMODULATOR CIRCUITS
In the FM mode, the filtered 2nd IF signal input from
pin 7 is amplified by the internal limiter amplifier, and FMdemodulated at the internal quadrature detector. The
demodulated AF signals are then output from pin 11 and
applied to the AF circuits via the AF switch (IC13).
AM DEMODULATOR CIRCUITS
In the AM mode, the filtered 2nd IF signal input from
pin 5 is amplified by the internal limiter amplifier, and AMdemodulated at the internal AM detector. The demodulated
AF signals are output from pin 14 and applied to the AF fi lter
circuits via the AF switch (IC13).
DIGITAL (DV) DEMODULATOR CIRCUITS
In the DV mode, the filtered 2nd IF signal input from
pin 7 is amplified by the internal limiter amplifier, and
FM-demodulated at the internal quadrature detector.
The demodulated AF signals are applied to the digital
demodulator circuits via the AF switch (IC13).
AF FILTER CIRCUITS
The demodulated AF signals are applied to the AF filter
(Q47) via the digital/analog signal selector (IC11), to obtain
suitable audio response the for receive mode (FM, AM or
DV).
The frequency response of the fi lter is controlled by “AFFIL_
SEL” signal from the CPU (IC25).
The fi ltered AF signals are applied to the variable pass-band
frequency audio filter circuit (IC49a; pins 3, 1). The circuit
reduces audible noises included in the demodulated AF
signals.
The fi ltered AF signals are applied to the electric volume IC
(IC66) which adjusts the loudness by “AF_VOL_DATA” and
“AF_VOL_CK” signals from the CPU (IC25).
The level-adjusted AF signals are applied to the AF power
AMP (IC38) via the AF mute SW (Q102).
The FM-demodulated AF signals from the AF switch (IC13)
are applied to the modem (IC1012) via the two buffers (IC49b;
pins 6, 7 and IC1014), and converted into the digital signal.
The converted digital signal is applied to the DSP CODEC
(IC1) via the level converter (IC1000, 1001, 1002), to be
decoded into the AMBE signal. The decoded AMBE signal is
then applied to the liner CODEC IC (IC1006) to be converted
into the analog audio signal. The converted AF signals are
applied to the RX AF circuits.
• DIGITAL (DV) DEMODULATOR CIRCUITS
From the FM demodulator
circuits (DV mode)
IC49b
BUFF
IC1000,1001,1002
LEVEL
BUFF
CNV.
IC1014
IC1012
MODEM
IC1006
CODEC
IC1013
To the AF filter circuits
(DV mode)
DSP
LINEAR
CODEC
AF POWER AMPLIFIER
The AF signals from the AF mute SW (Q102) are applied to
the AF power AMP (IC38), and amplifi ed to obtain AF output
power. The power-amplified AF signals are applied to the
internal speaker (CHASSIS; SP1) via J8.
If an external speaker is connected to the external speaker
jack (J8), the power-amplifi ed AF signals from the AF power
AMP (IC38) are applied to the connected speaker via J8.
• AF FILTER CIRCUITS AND AF POWER AMPLIFIER
[EXTERNAL SPEAKER JACK]
J8
SP1
Internal speaker
IC38
AF
AMP
Q102
MUTE
FILTER
IC66
SP
Volume
control
AF_VOL_DATA
AF_VOL_CK
IC11Q47IC49a
From the FM/AM demodulator circuits
AF
AF
FILTER
AFFIL_SEL
(FM/AM mode)
DIGI/AN
SELECT
From the digital demodulator circuits
(DV mode)
4 - 3
4-2 TRANSMITTER CIRCUITS
TX AF CIRCUITS
MIC signals from the connected microphone are passed
through the HPF (Q87), and amplified by the MIC AMP
(IC28). The amplified MIC signals are passed through the
MIC gain SW (Q88) which selects the MIC sensitivity from
“High” or “Low,” and the MIC mute SW (IC30), then passed
through or bypassed the ALC AMP (IC32) via the AF SWs
(IC29 and IC52).
In the DV mode, the MIC signals are applied to the ALC
AMP (IC32) which automatically adjusts the level of MIC
signals for digital processing,
• TX AF CIRCUITS
J2
1
2
3
Q87
4
5
MIC
6
7
8
From the microphone
Q88
IC28
MIC
HPF
AMP
MIC GAIN
SWITCH
IC30
IC29IC52
MIC
MUTE
AF
SW
ALC
AMP
IC32
The MIC signals from the AF SW (IC52) are passed through
the pre-emphasis and IDC (for amplitude-limitting) circuits
(IC48b), MIC level adjustment circuit (IC48a) and the
splatter circuit (IC48d) which cuts off the 3 kHz and higher
audio signals. The filtered MIC signals are applied to the
modulation circuits via the AF SW (IC51; pins 1, 7).
In the DV mode, the filtered MIC signals are applied to
the digital converter circuits before being applied to the
modulation circuits via the AF SW (IC51; pins 1, 6).
To the modulation circuits
IC48b
Pre-emphasis
AF
SW
IC48a
and IDC
Level
ADJ.
IC48d
SPLATTER
IC51
(FM mode)
AF
SW
To the digital converter circuits
(DV mode)
DA_SEL
DIGITAL CONVERTER CIRCUITS
The MIC signals from the TX AF circuits are applied to
the liner CODEC IC (IC1013) via the buffer (IC1014), and
encoded into the digital audio signal. The encoded digital
audio signal is then applied to the DSP CODEC IC (IC1006)
and converted into the AMBE signal. The AMBE signal
is applied to the modem (IC1012) via the level converter
(IC1000, 1001,1002). The modem IC converts the AMBE
signal into the analog signal, and output to the modulation
circuits via the buffer (IC1015) and the digital/analog line SW
(IC34).
• DIGITAL CONVERTER CIRCUITS
From the TX AF
circuits
IC1014
BUFF
IC1013
LINEAR
CODEC
IC1006
IC1012
MODEM
DSP
CODEC
IC1000,1001,1002
IC1015
BUFF
LEVEL
CNV.
IC34
To the modulation circuits
Digi/Ana
line SW
MODULATION CIRCUITS
The AF signals from the TX AF circuits (in FM mode) or
digital converter circuits (in DV mode) are applied to the AF
AMP (IC48c). The amplifi ed modulation signals are passed
through the D/A converter (IC8) to be adjusted its level
(=deviation), then applied to the VCO (VHF VCO: Q111,
D145–148/UHF VCO: Q73, D87, 91, 92) via the modulation
mute SWs (IC9, VHF; Q109/UHF; Q64) as the modulation
signals.
The modulated VCO oscillating signal is passed through the
buffer (VHF; Q113/UHF; Q76) and applied to the LO AMP
(IC45) via the VCO SW (VHF; D160, 175/UHF; D102).
The amplified VCO output signals are applied to the TX
amplifi er circuits.
• MODULATION CIRCUITS
Q113
BUFF
UHF VCO
Q73
D87,91,92
D160,D175
VCO
SW
D102
Q76
BUFF
IC45
To the TX amplifer
circuits
LO
AMP
VCO
SW
From the TX AF
circuits (FM mode)
From the digital converter
circuits (DV mode)
IC48c
AMP
IC9
IC8
MOD
MUTE
D/A
Q111
D145-148
Q109
VHF VCO
MOD
MUTE
Q64
MOD
MUTE
4 - 4
TX AMPLIFIER CIRCUITS (VHF BAND)
The output signal of VHF VCO (Q111, D145–148) is passed
through the LO SW (D155), LPF and ATT, then applied to
the drive AMP (Q25) via the limiter (D29), to obtain adequate
input level for the power AMP (power MOS-FET module;
IC3).
The amplifi ed TX signal is power-amplifi ed to 50 W (approx.;
25 W for [TPE] ver.) of output power (max.) by the power
AMP (IC3).
TX AMPLIFIERS (UHF BAND)
The output signal of UHF VCO (Q73, D87, 91, 92) is passed
through the LO SW (D103), HPF and ATT, then applied to
the pre-drive AMP (Q22). The amplifi ed TX signal is applied
to the drive AMP (Q26) via the limiter (D25) and amplifi ed to
obtain adequate input level for the power AMP (power MOSFET module; IC2).
The amplifi ed TX signal is power-amplifi ed to 50 W (approx.;
25 W for [TPE] ver.) of output power by the power AMP (IC2).
The power-amplified TX signal is passed through the LPF
which attenuates harmonic components to prescribed level,
then applied to the antenna connector via the power detector
(D39, 47, 1005), TX/RX SW (D59, 68, 75, 77) and two LPFs.
APC CIRCUITS (VHF BAND)
A portion of the TX signal from IC3 is rectifi ed at the power
detector (D39, 47, 1005), and converted into the DC voltage
which is in proportion to the RF power, and applied to the
operational amplifi er (IC4, pin 6). IC4 is an APC amplifi er for
both of V/UHF bands. The TX power setting voltage “PCON_
V” from the D/A converter (IC1) is applied to the pin 5 as
a reference. IC4 is rolled as a differential amplifier which
outputs voltage in inverse proportion to rectifi ed one.
When the TX power increased, the rectified voltage also
increased, that causes the decrease of output voltage of
differential amplifier. The decrease of output voltage of
differential amplifi er causes the drop of the gate voltage of
IC3, Thus the TX power maintained to keep stable level.
• TX AMPLIFIER AND APC CIRCUITS
VHF band TX signal ->
D155
LO SW
D29
ATTLPFLPF
LIMITER
DRIVE
AMP
Q25
The power-amplified TX signal is passed through the LPF
which attenuates harmonic components to prescribed level,
then applied to the antenna connector via the power detector
(D42, 52, 1006), TX/RX SW (D30, 53, 61, 62, 177), HPF and
LPF.
APC CIRCUITS (UHF BAND)
A portion of the TX signal from IC2 is rectifi ed at the power
detector (D42, 52, 1006), and converted into the DC voltage
which is in proportion to the RF power, and applied to the
operational amplifi er (IC4, pin 2). IC4 is an APC amplifi er for
both of V/UHF bands. The TX power setting voltage “PCON_
U” from the D/A converter (IC1) is applied to the pin 3 as
a reference. IC4 is rolled as a differential amplifier which
outputs voltage in inverse proportion to rectifi ed one.
When the TX power increased, the rectified voltage also
increased, that causes the decrease of output voltage of
differential amplifier. The decrease of output voltage of
differential amplifi er causes the drop of the gate voltage of
IC2, Thus the TX power maintained to keep stable level.
PWR
AMP
IC3
D39,D47,D1005
LPF
PWR
DET
D59,68,75,77
TX/RX
SW
LPF
From the frequency synthesizer
circuits
UHF TX signal ->
D103
LO SW
HPF
D25
Q22
PRE
DRIVE
ATT
LIMITER
DRIVE
AMP
Q26
T
IC2
PWR
AMP
PCON_U PCON_V
IC4
APC
CTRL
D42,52,1006
PWR
DET
D30,53,61,62,177
TX/RX
SW
To UHF RX circuitsTo VHF RX circuits
HPFLPF
4 - 5
4-3 FREQUENCY SYNTHESIZER
VCOs
VHF VCO
The VHF VCO is composed by the oscillator circuit (Q111,
D145, 146, 147) and buffer AMP (Q113), and generates
both of 1st LO signals and TX signal for VHF band.
The VCO oscillating signals are buffer-amplified by Q113,
amplifi ed by the LO AMP (IC45) to obtain adequate LO level,
then applied to the TX amplifi ers or 1st IF mixer via the LO
SW, ATT and fi lter.
While transmitting;
The VCO output signals from the LO AMP (IC45) are applied
to the TX amplifi ers via the LO SW (D155) as the TX signal.
While receiving;
The VCO output signals from the LO AMP (IC45) are passed
through the LO SW (D170), ATT and the LPF, then applied to
the 1st IF mixer (Q124), as the 1st LO signals for 140 MHz
band.
PLL
The PLL circuit provides stable oscillation of the transmit
frequency and receive 1st LO frequency. The PLL output
frequency is controlled by control signals including divide
ratio (“PLLCK,”"PLLDATA”and "PLLSTB") from the CPU
(IC25).
PLL (VHF VCO)
A portion of VHF VCO output signals from the buffer
(Q113) are applied to the PLL IC (IC14) via the VCO switch
(D175). The applied signals are divided at the prescaler and
programmable counter.
The divided signal is phase-compared with the 15.3 MHz
reference frequency signal from the reference frequency
oscillator (X5), at the phase detector.
The phase difference is output from pin 5 as a pulse type
signal after being passed through the internal charge pump.
The VCO output signals from the LO AMP (IC45) are passed
through the LO SW (D104), ATT, RF SW and LPF, then
applied to the 1st IF mixer (Q125), as the 1st LO signals for
300 MHz band.
UHF VCO
The UHF VCO is composed by the oscillator circuit (Q73,
D87, 91, 92) and buffer AMP (Q76), and generates both of
1st LO signals and TX signal for UHF band.
The VCO oscillating signals are buffer-amplified by Q76,
amplifi ed by the LO AMP (IC45) to obtain adequate LO level,
then applied to the TX amplifi ers or 1st IF mixer via the LO
SW, ATT and fi lter.
While transmitting;
The VCO output signals from the LO AMP (IC45) are applied
to the TX amplifi ers via the LO SW (D103) as the TX signal.
While receiving;
The VCO output signals from the LO AMP (IC45) are passed
through the LO SW (D101), ATT, doubler (HPF) and LPF,
then applied to the 1st IF mixer (IC64), as the 1st LO signals
for 800 MHz band.
The VCO output signals from the LO AMP (IC45) are passed
through the LO SW (D179), ATT and the LPF, then applied to
the 1st IF mixer (IC64), as the 1st LO signals for 440 MHz band.
The output signal is converted into the DC voltage (lock
voltage) by passing through the loop fi lter (R694-698, C759-
763). The lock voltage is applied to the variable capacitors
(D145, 146), and locked to keep the VCO frequency
constant.
PLL (UHF VCO)
A portion of VHF VCO output signals from the buffer (Q76)
are applied to the PLL IC (IC14) via the VCO switch (Q1015).
The applied signals are divided at the prescaler and
programmable counter.
The divided signal is phase-compared with the 15.3 MHz
reference frequency signal from the reference frequency
oscillator (X5), at the phase detector.
The phase difference is output from pins 15 and 16, and
passed through the external charge pump (Q61, 62) to be
converted into the pulse type signal.
The output signal is converted into the DC voltage (lock
voltage) by passing through the loop fi lter (R355, 362, 365,
369, 378, C451, 456, 473). The lock voltage is applied to the
variable capacitors (D91, 92), and locked to keep the VCO
frequency constant.
• FREQUENCY SYNTHESIZER CIRCUITS
PLLCK
PLLDATA
PLLSTB
X5
15.3MHz
TCXO
IC14
LOOP
FIL
PLL
IC
45.9 MHz
IF IC
IC15
IC1018
VCO
SELECT
Q52
X3
Q61,62
LOOP
FIL
VHF VCO
Q110,111
D145-148
UHF VCO
Q73
D87,91,92
Q113
BUFF
Q76
BUFF
D160,D175
VCO
SW
Q 1015
BUFF
D155
LO SW
D103
LO SW
D170
IC45
LO
AMP
D102
VCO
SW
LO SW
-> RX LO signals for 140 MHz band (118-174 MHz) ->
D179
LO SW
-> RX LO signals for 440 MHz band (420-550 MHz) ->
D101
LO SW
-> RX LO signals for 800MHz band (810-999 MHz) ->
D104
LO SW
-> RX LO signals for 300 MHz band (230-420 MHz) ->