man_ic-746.pdf

INSTRUCTION MANUAL

VHF/HF ALL MODE TRANSCEIVER

i746

This device complies with Part 15 of the FCC rules. Operation is sub-

ject to the following two conditions: (1) This device may not cause

harmful interference, and (2) this device must accept any interference

received, including interference that may cause undesired operation.

IMPORTANT

READ THIS INSTRUCTION MANUAL CAREFULLY

before attempting to operate the transceiver.

SAVE THIS INSTRUCTION MANUAL —This manual

contains important safety and operating instructions for

the IC-746.

PRECAUTIONS

R WARNING! HIGH VOLTAGE! NEVER attach an

antenna or internal antenna connector during trans-

mission. This may result in an electric shock or burn.

AVOID placing the transceiver against walls or putting

anything on top of the transceiver. This will obstruct

heat dissipation.

R NEVER apply AC to the [DC13.8V] socket on the

transceiver rear panel. This could cause a ﬁre or ruin

the transceiver.

During mobile operation, DO NOT operate the trans-

ceiver without running the vehicle’s engine. When

transceiver power is ON and your vehicle’s engine is

OFF, the vehicle’s battery will soon become exhausted.

R NEVER apply more than 16 V DC, such as a 24 V

battery, to the [DC13.8V] socket on the transceiver rear

panel. This could cause a ﬁre or ruin the transceiver.

Make sure the transceiver power is OFF before start-

ing the vehicle. This will avoid possible damage to the

transceiver by ignition voltage spikes.

R NEVER let metal, wire or other objects touch any in-

ternal part or connectors on the rear panel of the trans-

ceiver. This may result in an electric shock.

During maritime mobile operation, keep the transceiver

and microphone as far away as possible from the mag-

netic navigation compass to prevent erroneous indica-

tions.

NEVER allow children to play with equipment contain-

ing a radio transmitter.

BE CAREFUL! The heatsink will become hot when op-

erating the transceiver continuously for long periods.

NEVER expose the transceiver to rain, snow or any liq-

uids.

BE CAREFUL! If a linear amplifier is connected, set

the transceiver’s RF output power to less than the lin-

ear ampliﬁer’s maximum input level, otherwise, the lin-

ear ampliﬁer will be damaged.

AVOID using or placing the transceiver in areas with

temperatures below –10°C (+14°F) or above +60°C

(+140°F). Be aware that temperatures on a vehicle’s

dashboard can exceed 80°C (+176°F), resulting in per-

manent damage to the transceiver if left there for ex-

tended periods.

Use Icom microphones only (supplied or optional).

Other manufacturer’s microphones have different pin

assignments and connection to the IC-746 may dam-

age the transceiver.

AVOID placing the transceiver in excessively dusty en-

vironments or in direct sunlight.

EXPLICIT DEFINITIONS

BUILT-IN DSP

DSP

The explicit deﬁnitions described below apply to this in-

struction manual.

The IC-746’s DSP digitally transposes receive audio

components in all modes of operation to produce de-

sired AF frequency characteristics at the IF stage of

the transceiver. DSP provides the following functions:

WORD DEFINITION

R WARNING Personal injury, fire hazard or electric

shock may occur.

CAUTION Equipment damage may occur.

Noise reduction —reduces various types of noise

and enhances receive signal components only.

NOTE

If disregarded, inconvenience only. No risk

of personal injury, ﬁre or electric shock.

Automatic notch filter —automatically reduces single

beat interference and protects the receive voice signals.

The IC-746’s which display the “CE” symbol, comply

with the essential requirements of the 89/336/EEC di-

rective for Electromagnetic Compatibility. This compli-

ance is based on conformity with the ETSI speciﬁcation

prETS300 684 (EMC product standard for Commer-

cially Available Amateur Radio Equipment).

Selectable APF —a total of 3 passband widths are

selectable (80/160/320 Hz), for super-narrow filter

APF functions in CW mode. The APF center fre-

quency is adjustable.

TABLE OF CONTENTS

IMPORTANT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii

PRECAUTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii

EXPLICIT DEFINITIONS . . . . . . . . . . . . . . . . . . . . . ii

BUILT-IN DSP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii

TABLE OF CONTENTS . . . . . . . . . . . . . . . . . . . . . iii

7-3 Transferring a memory to VFO . . . . . . . . . . . 50

7-4 Clearing a memory . . . . . . . . . . . . . . . . . . . . 50

7-5 Selecting the call channel . . . . . . . . . . . . . . 51

7-6 Programming a memory . . . . . . . . . . . . . . . . 51

7-7 Programming the call channel . . . . . . . . . . . 52

7-8 Programming scan edges . . . . . . . . . . . . . . 52

7-9 Assigning memory names . . . . . . . . . . . . . . 53

7-10 Memo pads . . . . . . . . . . . . . . . . . . . . . . . . 54

1 PANEL DESCRIPTION . . . . . . . . . . . . . . . . . . 2–7

1-1 Front panel . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

1-2 Rear panel . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

1-3 Function display . . . . . . . . . . . . . . . . . . . . . . . 7

8 SCAN OPERATION . . . . . . . . . . . . . . . . . . . 55–58

8-1 Scan types . . . . . . . . . . . . . . . . . . . . . . . . . . 55

8-2 Programmed scan and

ﬁne programmed scan . . . . . . . . . . . . . . . . . 56

8-3 Memory scan . . . . . . . . . . . . . . . . . . . . . . . . 57

8-4 Select memory scan . . . . . . . . . . . . . . . . . . . 57

8-5 : F scan and ﬁne : F scan . . . . . . . . . . . . . . 58

2 MENU SELECTION . . . . . . . . . . . . . . . . . . . . . 8–9

2-1 Menu set 1 ﬂow chart . . . . . . . . . . . . . . . . . . . 8

2-2 Menu set 2 ﬂow chart . . . . . . . . . . . . . . . . . . . 9

3 BASIC OPERATION . . . . . . . . . . . . . . . . . . 10–17

3-1 Before operating . . . . . . . . . . . . . . . . . . . . . . 10

3-2 Squelch and receive (RF) sensitivity . . . . . . 12

3-3 Selecting VFO/memory mode . . . . . . . . . . . 13

3-4 Toggling between VFO A/B and transferring

contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

3-5 Setting a band and frequency . . . . . . . . . . . 14

3-6 Selecting an operating mode . . . . . . . . . . . . 17

9 INTERNAL ANTENNA TUNER . . . . . . . . . . . . . 59

9-1 Before operating . . . . . . . . . . . . . . . . . . . . . . 59

9-2 Tuner operation . . . . . . . . . . . . . . . . . . . . . . . 59

10 SET MODE . . . . . . . . . . . . . . . . . . . . . . . . . 60–64

10-1 Selecting set mode . . . . . . . . . . . . . . . . . . . 60

10-2 Set mode items . . . . . . . . . . . . . . . . . . . . . 60

4 USING DIFFERENT OPERATING MODES . 18–36

4-1 Operating SSB . . . . . . . . . . . . . . . . . . . . . . . 18

4-2 Operating CW . . . . . . . . . . . . . . . . . . . . . . . . 20

4-3 Operating RTTY (FSK) . . . . . . . . . . . . . . . . . 28

4-4 Operating AM . . . . . . . . . . . . . . . . . . . . . . . . 30

4-5 Operating FM . . . . . . . . . . . . . . . . . . . . . . . . 32

4-6 Repeater operation . . . . . . . . . . . . . . . . . . . 34

4-7 Packet operation . . . . . . . . . . . . . . . . . . . . . . 36

11 ADJUSTMENTS . . . . . . . . . . . . . . . . . . . . . 65–66

11-1 Tuning dial brake . . . . . . . . . . . . . . . . . . . . 65

11-2 Frequency calibration . . . . . . . . . . . . . . . . . 65

11-3 Measuring SWR . . . . . . . . . . . . . . . . . . . . . 66

11-4 Adjusting the LCD . . . . . . . . . . . . . . . . . . . 66

12 SETUP AND CONNECTIONS . . . . . . . . . . 67–75

12-1 Front panel . . . . . . . . . . . . . . . . . . . . . . . . . 67

12-2 Rear panel . . . . . . . . . . . . . . . . . . . . . . . . . 68

12-3 Selecting a location . . . . . . . . . . . . . . . . . . 69

12-4 Power supply connections . . . . . . . . . . . . . 69

12-5 Grounding . . . . . . . . . . . . . . . . . . . . . . . . . 70

12-6 Antenna . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

12-7 Data communications . . . . . . . . . . . . . . . . . 72

12-8 RTTY connections . . . . . . . . . . . . . . . . . . . 73

12-9 Remote jack . . . . . . . . . . . . . . . . . . . . . . . . 74

5 FUNCTIONS FOR RECEIVE . . . . . . . . . . . . 37–42

5-1 Simple band scope . . . . . . . . . . . . . . . . . . . . 37

5-2 Preamp and attenuator . . . . . . . . . . . . . . . . 38

5-3 RIT function . . . . . . . . . . . . . . . . . . . . . . . . . 38

5-4 AGC function . . . . . . . . . . . . . . . . . . . . . . . . 39

5-5 1/4 function . . . . . . . . . . . . . . . . . . . . . . . . . . 39

5-6 NB function . . . . . . . . . . . . . . . . . . . . . . . . . . 39

5-7 Noise reduction . . . . . . . . . . . . . . . . . . . . . . 40

5-8 Auto notch (ANF) function . . . . . . . . . . . . . . 40

5-9 Dial lock function . . . . . . . . . . . . . . . . . . . . . 40

5-10 Twin PBT . . . . . . . . . . . . . . . . . . . . . . . . . . 41

5-11 Selecting IF ﬁlters . . . . . . . . . . . . . . . . . . . . 42

13 OPTIONAL INSTALLATIONS . . . . . . . . . . 76–80

13-1 Opening the transceiver’s case . . . . . . . . . 76

13-2 UT-102 VOICE SYNTHESIZER UNIT . . . . . . . . . 77

13-3 CR-282 HIGH STABILITY CRYSTAL UNIT . . . . . 77

13-4 Optional IF ﬁlters . . . . . . . . . . . . . . . . . . . . 78

13-5 Linear ampliﬁer connections . . . . . . . . . . . 79

13-6 External antenna tuner connections . . . . . . 80

6 FUNCTIONS FOR TRANSMIT . . . . . . . . . . . 43–48

6-1 VOX function . . . . . . . . . . . . . . . . . . . . . . . . . 43

6-2 Break-in function . . . . . . . . . . . . . . . . . . . . . 44

6-3 : TX function . . . . . . . . . . . . . . . . . . . . . . . . 45

6-4 Monitor function . . . . . . . . . . . . . . . . . . . . . . 45

6-5 Speech compressor . . . . . . . . . . . . . . . . . . . 46

6-6 Split frequency operation . . . . . . . . . . . . . . . 47

6-7 Quick split function . . . . . . . . . . . . . . . . . . . . 48

14 MAINTENANCE . . . . . . . . . . . . . . . . . . . . . 81–83

14-1 Fuse replacement . . . . . . . . . . . . . . . . . . . 81

14-2 Resetting the CPU . . . . . . . . . . . . . . . . . . . 81

14-3 Troubleshooting . . . . . . . . . . . . . . . . . . . . . 82

7 MEMORY CHANNELS . . . . . . . . . . . . . . . . 49–54

7-1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

7-2 Memory channel selection . . . . . . . . . . . . . . 49

15 SPECIFICATIONS AND OPTIONS . . . . . . 84–85

15-1 Speciﬁcations . . . . . . . . . . . . . . . . . . . . . . . 84

15-2 Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85

iii

1 PANEL DESCRIPTION

1-1 Front panel

TUNER

ANT

POWER

NR APF

TRANSMIT

PHONES

APF/ANF

ELEC-KEY

AF RF/SQL

MIC

POWER SWITCH [POWER]

• When the tuner cannot tune the antenna, the tuning

circuit is bypassed automatically after 20 sec.

Push momentarily to turn power ON. (p. 11)

• Turn the optional DC power supply ON in advance.

ANTENNA SELECTOR SWITCH [ANT] (p. 71)

Toggles between the HF and 50 MHz antenna con-

nectors.

Push and hold to turn power OFF.

TRANSMIT SWITCH [TRANSMIT]

Toggles between transmit and receive.

• The [TX] indicator lights red while transmitting and the

[RX] indicator lights green when the squelch is open.

NOISE REDUCTION LEVEL CONTROL [NR]

(p. 40)

Adjusts the noise reduction level when the noise re-

duction function is in use. Set for maximum read-

ability.

HEADPHONE JACK [PHONES] (p. 67)

Accepts headphones.

• When headphones are connected, the internal speaker

or connected external speaker does not function.

AUDIO PEAK FILTER CONTROL [APF] (p. 20)

Varies the peak frequency of the audio peak ﬁlter to

pick out a CW signal from interference while the

APF function is ON.

ELECTRONIC KEYER JACK [ELEC-KEY] (p. 67)

Accepts a paddle to activate the internal electronic

keyer for CW operation.

• Selection between the internal electronic keyer, bug-key

and straight key operation can be made in keyer set

mode.

• A straight key jack is separately available on the rear

panel.

• Key polarity (dot and dash) can be reversed in keyer set

mode.

• 4-channel memory keyer is available for your conve-

nience.

NOISE REDUCTION SWITCH [NR] (p. 40)

Toggles the noise reduction function ON and OFF.

Functions in SSB, CW and RTTY modes.

AUDIO PEAK FILTER/AUTO NOTCH SWITCH

[APF/ANF]

Toggles between the audio peak (p.20) and auto

notch (p. 40) functions.

• The audio peak ﬁlter functions in CW mode only; the

auto notch functions in SSB, FM and AM modes only.

• The APF or ANF indicator appear in the display de-

pending on which function is selected.

MICROPHONE CONNECTOR [MIC]

Accepts the supplied or optional microphone.

• See p. 85 for appropriate microphones.

• See p. 67 for microphone connector information.

When the APF indicator appears, push this

switch for 1 sec., one or more times to select 320

Hz, 160 Hz or 80 Hz bandwidths.

• Use the [APF] control to vary the peak frequency.

ANTENNA TUNER SWITCH [TUNER] (p. 59)

Turns the antenna tuner ON and OFF (bypass)

when pushed momentarily.

AF CONTROL [AF] (inner control; p. 12)

Varies the audio output level from the speaker.

Starts to tune the antenna manually when

pushed for 2 sec.

PANEL DESCRIPTION

RF GAIN/SQUELCH CONTROL [RF/SQL] (p. 12)

Adjusts the RF gain and squelch threshold level.

The squelch removes noise output from the speaker

(closed condition) when no signal is received.

• The squelch is particularly effective for FM. It is also

available for other modes.

• The control can be set as the RF gain control only

(squelch is fixed open) or squelch control (RF gain is

ﬁxed at maximum) in set mode.

• Setting RF gain

Maximum

RF gain

Maximum

RF gain

sensitivity

Adjustable

range

Minimum

RF gain

sensitivity

• Setting squelch

Noise squelch

operating range

Squelch

threshold

S-meter squelch

threshold

Squelch

open

S-meter squelch

operating

range

!7 !8

MIC GAIN

RF PWR

CW PITCH

KEY SPEED

P.AMP/ATT

VOX/BK-IN MONITOR

MIC GAIN CONTROL [MIC GAIN]

Adjusts the microphone input gain.

turn the VOX function ON; push for 1 sec. to turn

the VOX function OFF. (p. 43)

In CW mode, push momentarily to select semi

break-in, full break-in or break-in OFF; push for 2

sec. to enter break-in set mode. (p. 44)

RF POWER CONTROL [RF PWR] (p. 84)

Continuously varies the RF output power from mini-

mum (2 W*) to maximum (100 W*).

*AM mode: 2–40 W, other modes: 5–100 W.

MONITOR SWITCH [MONI] (p. 45)

Push to toggle the monitor function ON and OFF.

CW PITCH CONTROL [CW PITCH] (p. 20)

Shifts the received CW audio pitch and monitored

CW audio pitch without changing the operating fre-

quency.

• The pitch can be changed from 300 to 900 Hz in approx.

3 Hz steps.

Push for 2 sec. to enter and exit monitor set

mode.

ELECTRONIC CW KEYER SPEED CONTROL

[KEY SPEED] (p. 22)

Adjusts the internal electronic CW keyer’s speed.

• 6 wpm to 60 wpm can be set.

PREAMP/ATTENUATOR SWITCH [P.AMP/ATT]

(p. 38)

Push momentarily to toggle between preamp-1

and preamp-2.

Push for 1 sec. to toggle the attenuator function

ON and OFF.

NOISE BLANKER SWITCH [NB] (p. 39)

Toggles the noise blanker ON and OFF. The noise

blanker reduces pulse-type noise such as that gen-

erated by automobile ignition systems. This function

cannot be used for FM, or non pulse-type noise.

VOX/BREAK-IN SWITCH [VOX/BK-IN]

In SSB, AM and FM modes, push momentarily to

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