Icom IC-F4101D, IC-F4102D, IC-F4103D, IC-F4106D Service Manual

S-14801XZ-C1
Apr. 2011

UHF TRANSCEIVERS

This service manual describes the latest technical
information for the IC-F4101D, IC-F4102D, IC-F4103D and

IC-F4106D

UHF TRANSCEIVERS, at the time of publication.

NEVER connect the transceiver to an AC outlet or to a DC

power supply that uses more than the specified voltage.
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.

MODEL VERSION

FREQUENCY

RANGE (MHz)

CHANNEL

SPACING (kHz)

IC-F4101D USA-01

400–470

6.25/12.5

IC-F4102D

EUR-01 6.25/12.5/20.0/25.0

UK-01

6.25/12.5/25.0IC-F4103D

EXP-01

EXP-02

EXP-03

EXP-07

350–400

EXP-08

AUS-01

400–470

IC-F4106D RUS-01

Be sure to include the following four points when ordering
replacement parts:

1. 10-digit Icom part number

2. Component name

3. Equipment model name and unit name

4. Quantity required

<ORDER EXAMPLE>

1110003491 S.IC TA31136FNG IC-F4101D MAIN UNIT 5 pieces

8820001210 Screw 2438 screw IC-F4101D Top cover 10 pieces

Addresses are provided on the inside back cover for your
convenience.

ORDERING PARTS

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 30 dB to 40 dB attenuator between
the transceiver and a Deviation Meter or Spectrum
Analyzer, when using such test equipment.

8. READ the instructions of the test equipment throughly
before connecting it to the transceiver.

REPAIR NOTES

INTRODUCTION

CAUTION

Icom, Icom Inc. and the Icom logo are registered trademarks of Icom Incorporated (Japan) in Japan, the United States, the
United Kingdom, Germany, France, Spain, Russia and/or other countries.

TABLE OF CONTENTS

SECTION 1 SPECIFICATIONS

SECTION 2 INSIDE VIEWS

SECTION 3 DISASSEMBLY INSTRUCTION

SECTION 4 CIRCUIT DESCRIPITON

4-1 RECEIVER CIRCUITS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1

4-2 TRANSMITTER CIRCUITS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2

4-3 FREQUENCY SYNTHESIZER CIRCUITS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3

4-4 VOLTAGE DIAGRAMS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3

4-5 PORT ALLOCATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-4

SECTION 5 ADJUSTMENT PROCEDURES

5-1 PREPARATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1

5-2 FREQUENCY ADJUSTMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-4

5-3 TRANSMIT ADJUSTMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-5

5-4 RECEIVE ADJUSTMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-7

SECTION 6 PARTS LIST

SECTION 7 MECHANICAL PARTS

SECTION 8 BOARD LAYOUTS

SECTION 9 BLOCK DIAGRAM

SECTION 10 VOLTAGE DIAGRAM

1 - 1

SECTION 1. SPECIFICATIONS

M GENERAL

• Frequency range : 400–470 MHz [USA-01], [EUR-01], [UK-01], [EXP-01], [EXP-02], [EXP-03],
[AUS-01], [RUS-01]

350–400 MHz [EXP-07], [EXP-08]

• Number of conventional channels : 16

• Type of emission : Wide 16K0F3E (30.0 kHz) Except [USA], [EUR], [UK]

16K0F3E (25.0 KHz) Except [USA]
Middle 14K0F3E (20.0 kHz) [EUR], [UK] only
Narrow 11K0F3E (15.0 kHz) Except [EUR], [UK]
8K50F3E (12.5 kHz)
Digital 4K00F1E, D (6.25 kHz)

• Antenna impedance : 50 Ω (nominal)

• Operating temperature range : –30˚C to +60˚C; –22˚F to +140˚F Except [EUR], [UK]

–25˚C to +55˚C [EUR], [UK]

• Power supply voltage : Specifi ed Icom's battery packs only (7.5 V DC; negative ground)

• Current drain (approximately) : Receiving 100 mA (in digital mode, stand-by)

400 mA (max. audio, with the internal speaker)
Transmitting 1.3 A (4 W)

• Dimensions

(projections not included)

: 58.0 (W)×111.0 (H)×36.5 (D) mm; 2.3 (W)×4.4 (H)×1.4 (D) in. (with BP-265)

• Weight (approximately) : 150 g; 5.3 oz.

310 g; 10.9 oz. (including MB-124, BP-265, FA-SC57U)

M TRANSMITTER

• Output power : 4 W

• Modulation : Variable reactance frequency modulation

• Maximum frequency deviation : Narrow ±2.5 kHz

Middle ±4.0 kHz [EUR], [UK] only
Wide ±5.0 kHz Except [USA]

• Frequency stability : ±1.0 ppm

• Spurious emissions : 70 dB min. Except [EUR], [UK]

0.25 µW (

≤

1 GHz)

[EUR], [UK]

1.00 µW (

>

1 GHz)

[EUR], [UK]

• Adjacent channel power : Narrow 60 dB min., 70 dB typ.

Middle 70 dB min., [EUR], [UK] only
Wide 70 dB min., 74 dB typ. Except [USA]
Digital 60 dB min., 66 dB typ.

• Audio harmonic distortion : 1.0% typ. (at AF 1 kHz, 40% deviation)

• FSK error : 5% max.

• FM hum and Noise (Except [EUR], [UK])

(without CCITT Filter)

: Narrow 34 dB min., 44 dB typ.

Wide 40 dB min., 50 dB typ. Except [USA]

• Rasidual modulation ([EUR], [UK] only)

(with CCITT Filter)

: Narrow 40 dB min.

Middle 43 dB min.
Wide 45 dB min.

• Limitting charact of modulator : 60–100% of max. deviation

• Input impedance (MIC) : 2.2 k

Ω

1 - 2

M RECEIVER

• Sensitivity : 0.24 µV typ. at 12 dB SINAD Except [EUR], [UK]

–4 dBµV (EMF) typ. at 20 dB SINAD [EUR], [UK]
–8 dBµV (EMF) typ. at 5% BER [Digital mode]

• Squelch sensitivity (at threshold) : 0.20 µV typ. Except [EUR], [UK]

–8 dBµV (EMF) typ. [EUR], [UK]

• Intermediate frequency : 1st IF; 46.35 MHz, 2nd IF; 450 kHz

• Adjacent channel selectivity : Narrow 60 dB min., 67 dB typ.

Middle 70 dB min. [EUR], [UK] only
Wide 70 dB min., 74 dB typ. Except [USA]
Digital 50 dB min., 58 dB typ.

• Spurious response : 70 dB min., 80 dB typ.

• Intermodulation : Narrow 70 dB min., 75 dB typ. Except [EUR], [UK]

Wide 70 dB min., 75 dB typ. Except [EUR], [UK], [USA]
Digital 65 dB min., 70 dB typ. Except [EUR], [UK]
65 dB min. [EUR], [UK]

• FM hum and Noise (Except [EUR], [UK])

(without CCITT Filter)

: Narrow 34 dB min., 42 dB typ.

Wide 40 dB min., 47 dB typ. Except [USA]

• FM hum and Noise ([EUR], [UK])

(with CCITT Filter)

: Narrow 40 dB min.

Middle 43 dB min.
Wide 45 dB min.

• Audio output power : 0.8 W typ. at 5% distorsion with a12 Ω load (internal speaker)

0.4 W typ. at 5% distorsion With an 8 Ω (external speaker)

• Audio output impedance : 8

Ω

Measurements made in accordance with TIA-603, EN 300 086 or EN 301 166.

All stated specifi cations are subject to change without notice or obligation.

2 - 1

SECTION 2. INSIDE VIEWS

• MAIN-A/MAIN-C UNIT
(TOP VIEW)

VCO

5 V REGULATOR
(IC54)

PLL CIRCUIT

APC AMP

(IC1)

TCXO

(X2)

3.3 V DC-DC CONVERTER
(IC65)

MIC AMP

(IC64)

2ND IF FILTER (For wide)
(FI3)

1ST IF FILTER
(FI2)

DISCRIMINATOR
(X1)

2ND IF FILTER (For narrow)
(FI4)

2ND IF FILTER (For digital)
(FI5)

AF AMP
(IC21)

AF AMP
(IC58)

2 - 2

• MAIN-A/MAIN-C UNIT
(BOTTOM VIEW)

TX POWER AMP
(Q1)

BUFFER

(Q28)

PLL LOCK VOLTAGE SW

(IC6)

CLOCK AMP

(IC905)

2ND IF AMP (For digital)

(IC5)

AF POWER AMP SW

(Q64)

DRIVE AMP
(Q2)

PRE-DRIVE AMP
(Q3)

PRE AMP
(Q4)

RF AMP
(Q22)

RF AMP GATE BIAS CONTROL
(Q21)

AF AMP

(IC55)

IF DEMODULATOR IC

(IC3)

BUFFER

(Q17)

1ST IF FILTER

(FI1)

R5 LINE REGULATOR

(Q72)

RIPPLE FILTER
(Q15)

1ST IF MIXER

(Q23)

AF POWER AMP

CONTROLLER

(Q63)

LINEAR CODEC

(IC902)

LINEAR CODEC/DSP CLOCK

(X900)

D/A CONVERTER
(IC57)

LPF/BUFFER/VOX AMP
(IC60)

CPU
(IC51)

PLL BUFFER
(Q9)

VCC LINE SW
(Q92)

3 - 1

SECTION 3. DISASSEMBLY INSTRUCTION

3 - 1

BE CAREFUL to not pull out the speaker wire when
separating the CHASSIS and the FRONT PANEL.

For easy separation of the CHASSIS

Use a suction lifter to lift the bottom of the CHASSIS up.

1. REMOVING THE CHASSIS

1) Remove the ANT connector nut and 2 knobs.

2. REMOVING THE MAIN UNIT

1) Remove the 9 screws and the side plate from the
MAIN UNIT.

2) Unsolder the 2 points shown, and then remove the
MAIN UNIT.

2) Remove 2 screws from the bottom of the CHASSIS.

3) Lift the bottom of the CHASSIS up in the direction
of the arrow.

4)

CAREFULLY lift the chassis out of the FRONT PANEL
and turn it over in order to unplug the speaker wire.

(Continued on the right above)

5) Remove the seals and nuts from the CHASSIS.

ANT CONNECTOR NUT

KNOB

FRONT PANEL

Remove with;

“ICOM Driver (K)”

(8960000110)

FRONT PANEL

CHASSIS

SCREW×2

SPEAKER

WIRE

CHASSIS

FRONT PANEL

TOP SEAL

NUT×2

SIDE SEAL

CHASSIS

Remove with;

“ICOM Driver (AG)”

(8960000560)

UNSOLDER

Solder
remover

CHASSIS

SCREW×9

PCB

MAIN UNIT

SIDE PLATE

Suction lifter

Suction lifter

• Part name : EA950R-2

• Manufacture : ESCO CO.LTD

4 - 1

SECTION 4. CIRCUIT DESCRIPTION

4-1 RECEIVER CIRCUITS

RF CIRCUITS

The RX signal from the antenna is passed through the LPF
and antenna SW (D3, D22), then filtered by the 2-staged
tuned BPF (D24 and D26) to eliminate unwanted out-of­band signals. The filtered RX signal is amplified by the RF
AMP (Q22), and filtered by another 2-staged tuned BPF
(D28) to obtain a good image response, then applied to the
1st IF circuits.

The BPFs are tuned to the RX frequency by applying ad­equate tuning voltages: “T1” and “T2” to the variable capaci­tors.

1ST IF CIRCUITS

The RX signal from the RF circuits is applied to the 1st IF
mixer (Q23) and mixed with the 1st LO signal from the RX
VCO, resulting in the 46.35 MHz 1st IF signal. The 1st IF sig­nal is passed through the IF SWs (D31–D34) and the crystal
fi lter (FI1: analog mode, FI2: digital mode) to be fi ltered, am­plified by the 1st IF AMP (Q24), then applied to the 2nd IF
circuits.

2ND IF AND DEMODULATOR CIRCUITS

The signal from the 1st IF circuits is applied to the IF demod­ulator IC (IC3) which contains the 2nd IF mixer, 2nd IF AMP,
FM detector, squelch circuit and AF AMP in its package.

The 1st IF signal is applied to the 2nd IF mixer and mixed
with the 2nd LO signal resulting in the 450 kHz 2nd IF signal.

The 2nd LO signal is generated by tripling the 15.3 MHz
reference frequency signal generated by the reference fre­quency oscillator (TCXO; X2).

• WHILE OPERATING IN THE ANALOG MODE

The 2nd IF signal is filtered by the 2nd IF filter (FI3: wide/
middle mode) or fi lters (FI3 and FI4: narrow) to eliminate un­wanted signals. It is amplifi ed by the 2nd IF AMP, and then
demodulated by the detector circuit, which employs the dis­criminator (X1) as the phase shifter.

The demodulated AF signal is amplified by the AF AMP
(IC21), and then applied to the linear codec (IC902) through
the fi lter SW (Q901). The fi lter SW toggles the frequency re­sponse of the AF fi lter (R904, R908, C924), according to the
type of reception; Wide, Mid or Narrow.

The AF signal is converted into a digital audio signal by the
linear codec (IC902), processed by the DSP (IC903), and
then decoded into an analog audio signal.

• WHILE OPERATING IN THE DIGITAL MODE

The 2nd IF signal is fi ltered by the 2nd IF fi lters (FI3 and FI4)
to eliminate unwanted signals and applied to the IF AMP
(IC5) through the buffer (Q28). The amplifi ed 2nd IF signal is
passed through the ceramic fi lter (FI5), and then directly ap­plied to the DSP (IC903).

The 2nd IF signal is demodulated by the DSP (IC903), and
then applied to the linear codec (IC902) to be decoded into
an analog audio signal.

The AF signal is applied to the RX AF circuits.

LPF

ANT

SW

D1,D22

RF
AMP

Q22

BPF

D28 D24,D26

BPF

T2

T1

From the TX circuits

To the 1st IF circuits

ANT

LO
SW

D5,D6

D31,D32D33,D34

Q23

BPF

XTAL

FI1

IF
AMP

Q24

BUFF

Q8

BUFF

Q10

ATT

IF SW

IF SW

RX VCO

To the TX circuits

From the RF circuits

2nd IF circuits

46.35MHz

BPF

XTAL

FI2

46.35MHz
1st IF mixer

PLL

IC

IC2

X3

Q26

BPF

X2

TCXO

W/N

SW

D38,D39

X1

Discriminator

BPF

CERAMIC

FI3

BPF

CERAMIC

FI4

W/N
SW

D36,D37

D/A

converter

IF IC

From the 1st IF

circuits

(Analog path)

To the RX AF circuit

(Digitalpath)

IC3

15.3MHz

45.9MHz

DISC

SQIN

IC57

450kHz

450kHz

NOIS

CERAMIC

BPF

FI5

DIF

BUFF

IC5

BUFF

Q28

A/D

IC901

FILTER

SW

Q901

DSP

LINEAR

DISC

CODEC

IC902

IC903

DAFO

AF

FILTER

R904,R908,C924

• 1ST IF CIRCUITS

• 2ND IF AND DEMODULATOR CIRCUITS

• RF CIRCUITS

4 - 2

RX AF CIRCUITS

The demodulated AF signal from the linear codec (IC902) is
passed through the LPF (IC60C), and then adjusted in level
by the D/A converter (IC57). The level-adjusted AF signal is
then amplifi ed by AF AMPs (IC58 and IC55).

The amplifi ed AF signal is applied to the internal or external
speaker.

SQUELCH CIRCUITS (Analog mode only)

The squelch circuit cuts off the AF output signals when no
RF signals are received. Detecting noise components in the
demodulated AF signals, the squelch circuit stops audio sig­nals being emitted.

A portion of demodulated AF signal from the IF IC (IC3) is
passed through the D/A converter (IC57) for level (=thresh­old) adjustment. The level-adjusted AF signals are passed
through the noise filter (IC3, pins 7, 8 and R139–R142,
C241–C243) to fi lter the noise components (approx. 30 kHz
signals) only. The noise components are rectified, resulting
in DC voltage corresponding to the noise level.

If the noise level is higher than the preset one, the internal
comparator set the “NOISE” signal to the CPU to “High”,
then the CPU turns the “AFON” signal which controlls the AF
power AMP (IC55) to “Low,” to inactivate it.

• RX AF CIRCUITS

• SQUELCH CIRCUITS

AF

AM P

AF

AMP

IC55 TPA0211DGN

J52

SP1

AF

AM P

J53

Int.speaker

Ext.speaker

1
2

LPF

IC60C

From the linear codec

IC58

AFON

AFO

DAFO

D/A

converter

IC57

DAC

Noise
AMP

Noise filter

From IF IC

(IC3, Pin16)

To RX AF circuits

Noise

detector

Com-

parator

NOISE SQUELCH DIAGRAM

“NOIS”

IC57

IC3

14

8

7

13

15

4-2 TRANSMITTER CIRCUITS

TX AF CIRCUITS

The audio signal from the internal or external microphone
(MIC signal) is passed through the MIC gain SW (IC62), and
then applied to the MIC AMP (IC64).

• WHILE OPERATING IN THE ANALOG MODE

The amplifi ed MIC signal is passed through the HPF (IC63A),
which attenuates frequencies 300 Hz and below, and then
applied to the limiter AMP (IC60A), through the mute SW
(Q66).

The amplitude-limited MIC signal is applied to the lin-

ear codec (IC902), through the MIC line SW (IC66).

The MIC signal is converted into a digital audio signal by the
linear codec (IC902), processed by the DSP (IC903), and
then converted into an analog baseband signal (modulation
signal).

• WHILE OPERATING IN THE DIGITAL MODE

The amplifi ed MIC signal is applied to the ALC (IC63B) which
keeps the signal level fi xed.

The level-adjusted MIC signal is

applied to the linear codec

(IC902) through the MIC line SW (IC66).

The MIC signal is converted into a digital audio signal by the
linear codec (IC902), processed by the DSP (IC903), and
then converted into the digital baseband signal (modulation
signal).

The signal from the linear codec (IC902) is passed through
the LPF (IC60B), and then applied to the D/A converter
(IC57)

which adjusts its level (=deviation)

. The level-adjusted

modulation signal is applied to the modulation circuit.

• TX AF CIRCUITS

MC51

[Ext. MIC]

[Int. MIC]

J51

MIC

GAIN

SW

IC62

AMP

IC64

ALC
AMP

IC63B

HPF

IC63A

LIMIT
AMP

IC60A

MIC

LINE

IC66

SW

MUTE

SW

Q66

DMI

To the modulation circuit

DSP

LINEAR

CODEC

IC902

IC903

LPF

IC60B

MOD DMO

D/A

IC57

4 - 3

MODULATION CIRCUIT

The modulation signal from the TX AF circuits is applied to
D15 of the TX VCO (Q14, D14–D16) to modulate it (FM for
the analog mode, 4FSK for the digital mode). The modulated
signal from the TX VCO is buffer-amplified by two buffers
(Q8, Q10), and applied to the TX AMP circuits through the
LO SW (D5).

TX AMPLIFIERS

The buffer amplifi ed signal from the LO SW (D5) is sequen­tially amplified by the pre-AMP (Q4), pre-drive AMP (Q3),
drive AMP (Q2), and power AMP (Q1), to obtain TX power.
The amplifi ed TX signal is passed through the antenna SW
(D3, D22) and the LPF, which eliminates harmonics, and
then fed to the antenna.

APC CIRCUITS

D1 and D2 rectify a portion of the TX signal to direct voltage,
and the APC AMP (IC1) compares the voltage and the TX
power control reference voltage, “T1.” The resulting voltage
controls the gain of the power and drive AMPs to keep the
TX power constant.

• FREQUENCY SYNTHESIZER CIRCUITS

• TX AMPLIFIERS AND APC CIRCUITS

5-4 VOLTAGE DIAGRAMS

LO
SW

D5

Q14,
D14,D16,D17

MODULATION

FM:Analog
4-FSK: Digital

D15

BUFF

Q8

BUFF

Q10

TX VCO

From the TX AF circuits

To the TX AMP circuits

MOD

LPF

PWR

DET

D1,D2

MUTE

SW

Q6

ANT
SW

D1,D22

PWR
AMP

Q1

APC
AMP

IC1

DRIVE
AMP

Q2

AMP

PRE

Q4

DRIVE

PRE

Q3

T1

TMUT

ANT

From the

TX VCO

To the RX circuits

• MODULATION CIRCUIT

LPF

LPF

LO
SW

D5,D6

Q13,D12

Q14,D16

FILTER

LOOP

PLL

IC

SO,SCL,PLST

IC4

X3

Q26

Q23

To the TX AMPs

BPF

BUFF

Q8

BUFF

Q10

BUFF

Q9

X2

TCXO

LV

ADJ

D14

LV

ADJ

D11

BUFF

IC60

IF IC

RX VCO

TX VCO

IC3

REF

BAL

15.3MHz

45.9MHz

1st IF mixer

LV

LVA

S5
REG

Q71

,Q86

REG

R5

Q72

,Q87

REG

T5

Q73

,Q88

F51

R1(CHASSIS)

12

BT1

REG

+5V

IC54

DC-DC

1.6V

IC900

DC-DC

3.3V

IC65

REG

+3.3V

Q90

,Q91

Q92,
Q93,
D59

POWER

SW

LINE

FILTER

LINE
FILTER

LINE
FILTER

LINE

FILTER

VCC

+5V

T5V

Transmit circuits

Receive circuits

TX/RX common circuits

TX/RX common circuits

Logic circuits

R5V

S5V

TXC

RXC

S5C

VCC CPUV

CVDD_1.6 V

3.3V_VD D

+3.3V

+3.3V_A

+3.3V

PWON

POSWH

DVDD_3.3V

DSP

DSP flash

Liner codec

DSP reference voltage

CPUV

4-3

FREQUENCY SYNTHESIZER CIRCUITS

The RX VCO is composed of Q13, and D11, D12. The VCO
output signal is buffer-amplifi ed by two buffers (Q8 and Q10)
and applied to the 1st IF mixer, through the LO SW (D6) and
the LPF (L18, C208, C209).

The TX VCO is composed of Q14 and D14–D17. The VCO
output signal is buffer-amplifi ed by two buffers (Q8 and Q10)
and applied to the pre-AMP (Q4), through the LO SW (D5)
and the LPF.

A portion of signal generated by each VCO is fed back to
the PLL IC (IC4, pin 17) through the buffer (Q9) and the LPF
(L46, C167, C168).

The applied VCO output signal is divided and phase-com­pared with a 15.3 MHz reference frequency signal from the
TCXO (X2), which is also divided. The resulting signal is
output from the PLL IC (IC4), and DC-converted by the loop
fi lter, and then applied to the VCO as the lock voltage.

When the oscillation frequency drifts, its phase changes
from that of the reference frequency, causing a lock voltage
change to compensate for the drift in the VCO oscillating fre­quency.

4 - 4

4-5 PORT ALLOCATIONS

• CPU (IC51)

• D/A CONVERTER (IC57)

PIN
No.

LINE

NAME

DESCRIPTION

3 BAL DTCS balance adjustment.

4 AFVO AF volume adjustment.

12 TENC Outputs CTCSS deviation adjustment.

15 SQLC Squelch threshold setting.

16 T1

During RX: Outputs BPF tuning voltage.
During TX: Outputs TX power reference

voltage.

19 T2 Outputs BPF tuning voltage.

20 REF Outputs reference frequency adjust voltage.

23 LVA Outputs additional lock voltage adjustment.

24 MOD Max. deviation/AF volume adjustment.

BALL

No.

LINE

NAME

DESCRIPTION

I/O

A5 RXC

Power supply switching control.
H= During receive or stand-by.

O

A6 RMUTE

RX AF mute switch control.
L= During the squelch circuit is

activated.

O

A7 DMOSI Serial data to the DSP (IC903). O

A15 PWON

Power supply switching control.
H= The transceiver's power is ON.

O

B12 NOIS

Noise level detect.
H= Squelch close.

I

B15 AFON

AF power AMP control.
H= AF power AMP (IC55) is activated.

O

C1, C2CBI2,

CBI0

[ROTARY SELECTOR] input. I

C5 TXC

Power supply switching control.
H= While transmitting.

O

C8 ESDA EEPROM (IC52) serial data. I/O

C13 POSW [POWER] input. I

C14 ADS

1st IF filters (FI1 and FI2) switching
control.
L= During digital mode.

O

C15 NWC

Receive bandwidth switching.
L= During narrow mode.

O

D2, D3CBI3,

CBI1

[ROTARY SELECTOR] input. I

D6 DSCK DSP (IC903) clock. O
D8 ESCL EEPROM (IC52) clock. O

D13 DPDN

DSP (IC903) power control.
H= DSP is inactivated.

O

D14 DRES

DSP (IC903) reset.
L= Reset.

O

D15 CSFT

Clock frequency shift.
H= Clock frequency is shifted.

O

E13 RES CPU reset. I

H1 SIDE1

[UPPER] key input.
L= Pushed.

I

H2 SIDE2

[LOWER] key input.
L= Pushed.

I

J1 IPTT

Internal [PTT] input.
L= Pushed.

I

J2 XPTT

External PTT input.
H= An external PTT is pushed.

I

L1, L2

MCG0,

MCG1

MIC gain control. O

L12 TLED

Busy LED (Red) control.
L= LED lights

. (While transmitting)

O

L13 RLED

Busy LED (Green) control.
L= LED lights. (While receiving a signal)

O

L14 SSO Common serial data. O
L15 SCK Common clock. O

M1 TMUT

Transmission mute.
L= TX inhibit.

O

M2 ATX

Automatic TX control for VOX mode.
H= While MIC audio from the

connected headset is detected.

O

M8 BEEP Beep audio. (Square waves) O

M11 MDET External connection detect. I

M14 DAST

D/A converter (IC57) strobe.
H= Load enable.

O

BALL

No.

LINE

NAME

DESCRIPTION

I/O

N11 VOXV Microphone input sensing voltage. I
N12 BATV Battery voltage sensing. I
N14 DMISO DSP (IC903) serial data. O

P4 PLSW

PLL lock up time control.
L= Fast lock up.

O

P10 TEMP Temperature sensing voltage. I
P11 RSSI RSSI sensing voltage. I
P12 AFVI [VOLUME CONTROL] input. I
P15 DSS DSP (IC903) chip select. O

R3 S5C

Power supply line "S5C" switching
control.
H= Supplying current to the TX/RX

common circuits.

O

R4 PLST PLL strobe. O

R10 LVIN Lock voltage input. I