ICOM IC-28H VHF FM Transceiver Instruction Manual

Congratulations for choosing this technically-advanced ICOM product. The IC-28H VHF FM transceiver is the latest addition to the ICOM system of Amateur radio equipment. It features provision for the Digital Code Squelch method of communicating and a full 45 watts of output power for extended communication range.

Unpacking

The following accessories are supplied with the IC-28H:

Microphone (HM-12 for U.S.A., HM-15 for Europe, Italy, Spain)
Microphone hanger
Power cable
Fuses (15A)
External speaker plug
Mounting bracket
Mounting bracket knobs
Mounting screws (self-tapping)
Mounting screws
Flat washers (large)
Flat washers (small)
Nuts
Screws/spring washers
Support bracket
Cable lugs

Specifications

General

Frequency Coverage: 144 MHz band
Frequency Resolution: Not specified
Frequency Control: Not specified
Memory Channels: 21
Usable Temperature Range: Not specified
Power Supply Requirement: 13.8 V DC
Current Drain (at 13.8 V DC): Not specified
Antenna Impedance: 50 ohm
Dimensions: Not specified
Weight: Not specified

Transmitter

Output Power: 45W (High), 5W (Low)
Emission Mode: 16K0F3E
Modulation System: Not specified
Max. Frequency Deviation: Not specified
Spurious Emission: Not specified
Microphone: Electret condenser

Receiver

Receive System: Double-conversion superheterodyne
Modulation Acceptance: Not specified
Intermediate Frequencies: 1st 17.2 MHz, 2nd 455 kHz
Selectivity: More than 12.5 kHz at -6 dB, Less than 25.0 kHz at -60 dB
Sensitivity: Less than 0.18 µV for 12 dB SINAD
Audio Output: More than 2.4 watts at 10% distortion with 8 ohm load
Audio Output Impedance: 4 ~ 8 ohms

* All stated specifications are approximate and subject to change without notice or obligation.

Features

Compact and High Output Power (144MHz Mobile)
Simple Panel Design
Highly Visible LCD Readout with Automatic Dimmer Circuit
21 Memory Channels
Dual Scanning Functions (Frequency Scan, Memory Scan)
Subaudible Tone Encoder Standard
Squelch Options (including optional Digital Code Squelch and Tone Squelch units)

Control Functions

Front Panel

(1) VOLUME CONTROL/POWER SWITCH [VOL/PWR]: Push to turn power ON/OFF. Turn clockwise to increase audio level.
(2) SQUELCH CONTROL/CHECK SWITCH [SQL/CHK]: Quiets receiver noise. Turn clockwise until T/R LED goes out. Push to monitor transmit frequency in duplex mode.
(3) VFO/MEMORY READ SWITCH [VFO/MR]: Selects VFO or Memory mode. 'M' appears on LCD in Memory mode.
(4) SET SWITCH [SET]: Multi-function switch for programming subaudible tones, transmit offset, tuning step size (VFO mode), or skip function (Memory mode).
(5) TUNING CONTROL: Adjusts operating frequency (VFO mode) or selects memory channel (Memory mode). Also used for programming settings.
(6) DOWN/UP SWITCH [DOWN/UP]: Changes frequency or memory channel incrementally. Holding down initiates scan.
(7) TONE SWITCH [TONE] / CALL SWITCH [CALL]: (U.S.A. version: TONE) Push to turn subaudible tone encoder ON/OFF. (Except U.S.A.: CALL) Push to select call channel (memory channel 21). 'C' appears on LCD.
(8) WRITE SWITCH [WRITE]: Stores displayed frequency and settings into memory channel (VFO mode). Transfers memory contents to VFO (Memory mode).
(9) HIGH/LOW SWITCH [HI/LO]: Selects HIGH (45W) or LOW (5W) transmit output power. 'LOW' appears on display for low power.
(10) TRANSMIT/RECEIVE INDICATOR [T/R]: Red LED indicates transmit mode, green LED indicates receive mode (squelch open). OFF when squelch is closed.
(11) DISPLAY DIMMER SENSOR: Senses ambient light to automatically adjust LCD backlighting.
(12) DUPLEX SWITCH [DUP]: Selects simplex (no indicator), DUP- (transmit freq. lower than receive), or DUP+ (transmit freq. higher than receive).
(13) MIC CONNECTOR: Connects the supplied microphone. Pinout details provided.
(14) TONE SQUELCH SWITCH DIGITAL SQUELCH SWITCH [T/D.SQL]: Activates optional tone squelch or digital code squelch systems. 'TONE' and/or 'D.SQL' appear on display.

LCD Readout Indicators

Frequency Display (15): Shows operating frequency.
TONE Indicator (16): Appears when subaudible tone encoder is activated.
DUP- / DUP+ Indicators (17, 18): Appear when duplex mode is active.
OW Indicator (18): Flashes when ready to program transmit offset.
AQS / D.SQL Indicators (19, 20): Appear when optional squelch units are activated.
Memory Channel Number (21): Displays selected memory channel (1-21).
MEMORY MODE INDICATOR 'M' (22): Appears when Memory mode is selected.
MEMORY CHANNEL SKIP INDICATOR 'SKIP' (23): Appears when a memory channel is programmed to be skipped during scanning.
S/RF INDICATOR (24): Acts as S-meter in receive mode, shows relative output power in transmit mode.
TUNING STEP INDICATOR 'TS' (25): Flashes when ready to program tuning step size.
OUTPUT POWER INDICATOR 'LOW' (26): Appears when LOW power (5W) is selected.

Installation

Mobile Installation

Location: Avoid extreme temperatures, direct airflow, and locations hindering vehicle operation. Mount securely to minimize vibration.
Mounting: Use the supplied bracket, allowing for angle adjustment (approx. 22 degrees) for optimal viewing.
Power Connection: Connect directly to a 12V battery (RED to POSITIVE, BLACK to NEGATIVE). Do not connect to a 24V battery or use the cigarette lighter socket. Insulate cables passing through vehicle body holes.
Antenna: Use a high-quality 50-ohm antenna. Performance depends on antenna quality and location (gutter, bumper, trunk, roof). Use larger diameter coaxial cable for reduced loss.
Microphone: Connect the supplied electret condenser microphone to the front panel jack. Optional microphones are available.
External Speaker: Connect a 4-8 ohm speaker to the external speaker jack. This disconnects the internal speaker. The SP-10 is recommended.

Fixed Installation

Requires a stable AC power supply (13.8V DC, 25A max.).
Ensure source voltage does not exceed 16V DC.
Use a low-loss coaxial cable and a suitable directional antenna for best performance.

Operation

Receiving

Turn power ON using [VOL/PWR].
Adjust volume with [VOL/PWR].
Adjust squelch with [SQL/CHK] until noise is quieted (T/R LED goes out).
Select operating frequency using [TUNING CONTROL] or microphone UP/DN switches. If in Memory mode ('M' displayed), switch to VFO mode using [VFO/MR].

Transmitting

Ensure transmit frequency is not in use.
Push and hold the PTT switch on the microphone. The red T/R indicator lights.
Speak into the microphone at a normal voice level.
Release the PTT switch to stop transmitting.

Selecting Output Power

Push the [HI/LO] switch to toggle between HIGH (45W) and LOW (5W) power. The 'LOW' indicator appears when low power is selected.

Memory Mode

Memory Reading: Push [MR] on [VFO/MR] switch. 'M' appears on LCD. Use [TUNING CONTROL] or UP/DN switches to select memory channel.
Memory Programming: Select desired memory channel, switch to VFO mode, set frequency, then push and hold [WRITE] switch for ~0.5 seconds until 3 tones are heard. Confirm by switching back to Memory mode.
Memory Channel to VFO Transfer: Select memory channel, push and hold [WRITE] switch for ~0.5 seconds. The frequency transfers to VFO, and the unit switches to VFO mode.

Scan Functions

Frequency Scanning: Select VFO mode. Push and hold microphone UP/DN switch (~0.5 sec) to start scanning. Decimal point blinks. Scan stops on signals. Push UP/DN to cancel.
Memory Channel Scanning: Select Memory mode. Push and hold microphone UP/DN switch (~0.5 sec) to start scanning. Push UP/DN to cancel.
Memory Skip Function: In Memory mode, select channel, push [SET] switch. 'SKIP' indicator appears. Channel is skipped during scan. Push [SET] again to cancel skip.

Duplex Mode

Duplex Programming: Select VFO mode. Push [SET] until 'OW' flashes. Select offset type (F for fixed 600kHz, P for programmable). Use [DOWN/UP] to select offset value. Push [VFO/MR] to select VFO mode. Push [DUP] to select DUP- or DUP+. Push [SQL/CHK] to monitor transmit frequency.
Subaudible Tone Encoder: Used for repeater access. Program tone number using [SET] switch and [TUNING CONTROL]. Activate with [TONE] switch. Transmits tone when PTT is pressed.
1750Hz Tone Burst Function (Europe, etc.): Select duplex mode. Push microphone [TONE] switch. Transmit.

Call Channel Function (Except U.S.A.)

Using Call Function: Push [CALL] switch. 'C' appears on LCD, selecting memory channel 21. Push [CALL] again to release.
Programming Call Channel: Follow memory programming procedure for memory channel 21.

Backup Battery

A lithium battery backs up internal memory. Replace after approximately five years or if display malfunctions occur. Replacement should be done by an authorized ICOM dealer.

Resetting Internal Microcomputer (CPU)

If the transceiver displays erroneous information, turn power off, wait, then turn on. If problem persists, turn power on, insert a non-metallic probe into the reset hole on the bottom cover, and push the reset switch. All memory channels will be erased and must be reprogrammed.

Maintenance

Operating Environment: Avoid excessive heat, humidity, dust, and strong vibrations. Protect from water damage.
Adjustments: No internal adjustments are required as components are factory-set.
Malfunctions: Resetting the CPU often resolves issues. Refer to SECTION 5-8.
Cleaning: Remove knobs, use a soft cloth with mild soapy solution. Wipe dry. Do not use strong solvents.
Fuses: Locate and correct the cause of a blown fuse before replacing the 15A fuse in the DC power cable.

Troubleshooting

Problem	Possible Cause	Solution
No power on	Improper power cable connection, poor connector contact, wrong polarity, blown fuse.	Check connections, polarity, and fuses. Replace fuse if blown.
No sound from speaker	Volume too low, squelch set incorrectly, external speaker connected.	Adjust volume, adjust squelch, check external speaker connection.
Low sensitivity	Antenna feedline issue.	Check and replace feedline if necessary.
No or low RF output	LOW power selected, PTT switch/mic connector issue.	Select HIGH power, check mic connector.
No transmitter modulation	Poor mic connector connection.	Check mic connector.
Frequency not changing with Tuning Control	Memory mode selected.	Select VFO mode.
Abnormal frequency displayed	CPU malfunction, exhausted backup battery.	Reset CPU. If persists, contact dealer.
Scan functions do not stop on signals	Squelch control set incorrectly.	Adjust squelch correctly.
Memory frequencies change after CPU reset	All memories are initialized after reset.	Reprogram memory channels.

Optional Units

UT-28 Digital Code Squelch Unit

Provides a personalized squelch using 1 of 100,000 different code numbers. Requires identical programming on both radios. Scanning function cannot be used when activated.

UT-29 Tone Squelch Unit

A subaudible tone encoder/decoder. Requires simplex mode for operation. Refer to the unit's instruction sheet for details.

Programming Optional Units

UT-28: Push [T/D.SQL]. Push [SET] to flash 'D.SQL'. Use [DOWN/UP] to select code memory, push [SET] again to flash digits. Use [TUNING CONTROL] to set digits. Push [SET] to confirm.

UT-29: Use duplex switch for simplex. Push [T/D.SQL]. Push [SET] to flash 'D.SQL' and 'TONE'. Use [DOWN/UP] to select tone memory, use [TUNING CONTROL] to select tone number. Push [SET] to confirm.

Block Diagram

A block diagram illustrating the internal circuitry of the IC-28H is provided, showing the relationship between the various units such as the CPU, RF unit, and optional unit interfaces.

Accessories

Various optional accessories are available, including:

Base Station AC Power Supply (IC-PS30)
Microphones (DTMF, Speaker-microphone, Desk Microphone)
External Speakers (SP-10, SP-7)
Digital Code Squelch Unit (UT-28)
Tone Squelch Unit (UT-29)
Switch Box for HS-15 Microphone

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