Icom M25D VHF/Marine Radio Telephone Owners Manual

Introduction

You are now the proud owner of one of the finest VHF FM Marine Transceivers on the market today. It was designed and built by ICOM INCORPORATED, a long time leader in the field of VHF communication. ICOM has put all the technology and experience gained over the years into a transceiver that was built from the ground up specifically for Marine use. The ICOM M25D is expected to provide years of enjoyment and dependable communication.

Features

• 24 programmable channels plus weather pre-programmed.
• All solid state, including the 25 Watt Power Amplifier module.
• Weather and dust-tight case; molded aluminum frame; heavily protected covers for lasting attractiveness.
• No moving controls inside - PA and RF switching are solid state.
• Snap-in mounting bracket; adjustable angle; lockable for security.
• Advanced RF front end with helical resonators, MOSFETs, and crystal/mechanical filter for adjacent channel and inter-modulation rejection.
• Auto Monitor for Channel 16.
• High power, distortion-free audio output.
• Complete line of accessories available.

Specifications

General

Receiver Section

Transmitter Section

Installation

Planning

Select a location for your transceiver that allows free access to the front controls, good air circulation, and rear clearance for the fuse and cable connectors. Provide the best protection possible from direct rain or heavy seas. Avoid long cable runs to the antenna and power source. Keep power and antenna cables as far as possible from electrical sources such as generators, alternators, and electrical pumps. Stay away from magnetic compasses with the cables, and avoid running the antenna cable near electronic instruments.

Procedures

Your ICOM transceiver is supplied with a universal bracket that allows "over" or "under" mounting. Place the bracket where the unit is adequately supported when considering wave shock and vibration. The transceiver is shipped inside the mount, and the unit is easily removed by releasing the two side catches. The supplied mounting hardware will fit most installations, but special mounting fasteners may be needed. Any good marine supply store can assist. As with any marine installation, it is recommended that high-quality marine fasteners be used. Try to avoid drilling new mounting holes in the bracket, as this may affect the balance of the set.

Image description: Diagram showing the Icom M25D transceiver and its universal mounting bracket, illustrating different mounting orientations.

Electrical Connections

Primary Power

If possible, do not exceed the 10 feet length of the power cable supplied. If a run over 10 feet is necessary, use the wire gauge specified in the following table. Color coding of the power cable is as follows: Red is for positive (+) side of the battery, black for minus (-). The blue and white wires are for the microphone hanger; the looped wire is for connection of an external speaker. When hooking up the red and black wires, make the splice as close as possible to the power side of the fuse holder. Solder all connections and ensure they are clean, tight, and moisture-free. Be sure to leave a service margin in the power cable so that the set can be removed from the bracket without straining the cable.

Image description: Diagram illustrating electrical connections for the Icom M25D, showing antenna, power, speaker, and accessory connectors. Also shows the microphone hanger cord and power cord details.

External Speaker

To connect the External Speaker, cut the small looped wire at the power cord/mic hanger plug, and connect an 8 ohm speaker to the wires. Solder them and cover with plastic tape.

Antenna

Any marine antenna of good quality and 50 ohms impedance will suffice, but the use of a gain antenna is recommended. The antenna is the single most important item that will influence the performance of the transceiver. Location is also important; if you have any doubt, request the assistance of your dealer's technician. Follow the antenna marker's directions exactly. For an existing antenna, ensure that all connections are corrosion-free and firmly seated.

Preliminary Set up

The permanently mounted microphone attached to your transceiver should now be placed at a convenient location where the cable will neither interfere with your craft's operation while in its hanger, nor with your use or the crew's use. The CH 16 Auto-Monitor control cable should be routed out of the way and connected to the marked receptacle at the rear of the set.

Change or Addition of Channels

The design of the ICOM Marine Radiotelephone provides an inexpensive means for expanding channel capability. The services of a dealer's technician are required for installation and alignment. Additional channel(s) may be placed anywhere on the dial, but be sure to take along the labeling material supplied, which is found in the accessories. Additional weather channels can also be installed on the dial.

Accessories

• [1] Mounting Bracket
• [2] Power Cord and Microphone Hanger Box
• [3] Mounting Screws
• [4] Mounting Washers
• [5] Mounting Nuts
• [6] Keys
• [7] Fuses 10A
• [8] Microphone Hanger Box Mounting Screws
• [9] Labeling Kit

Image description: Illustration of the Icom M25D accessories, including mounting bracket, power cord, screws, washers, nuts, keys, fuses, and labeling kit.

Pre-Operation

Licenses Required

1. Ship Station License: Your craft, when equipped with VHF/FM equipment, has a radio station on board which, if used, must have a current license. It is unlawful to operate a Ship Station which is not licensed. Inquire through your dealer or appropriate government agency for an application for a Ship Radio-Telephone license. Your craft station will be issued a call sign.
2. Operators License: A Restricted Radiotelephone Operator Permit is the license most often held by small vessel radio operators if a radio is not required for safety purposes. This permit can usually be obtained by mail without examination. Contact your marine dealer or appropriate government agency for information or application. The Restricted Radiotelephone Operator Permit must be posted or kept on the person of the operator. Only a licensed radio operator may operate a radiotelephone transmitter. However, non-licensed individuals may talk over a radiotelephone if a licensed operator starts, supervises, ends the call, and makes necessary log entries. A current copy of the appropriate government agency rules and regulations is usually required to be kept.

Logs and Documents

Most countries require that a log of all contacts made over the Radiotelephone be kept. The Ship Radiotelephone Station licensee is responsible for compliance.

Operation

Controls and Indicators

• 1. Power ON/OFF (PWR): A double position push type switch that controls the Source Voltage applied to the radio. The switch is "in" for the on position.
• 2. Transmit High/Low Switch (HI-LO): Controls the transmitter output level. In the LO position, the output is 1 watt, sufficient for local communication. In the HI position, the output is a full 25 watts for long distance communication.
• 3. Volume (VOL): Controls the Audio Output level of the receiver.
• 4. Squelch (SQL): Sets the squelch sensitivity which quiets the receiver when no signal is present.
• 5. Weather (WX): Press this button momentarily to switch the receiver to the weather channel.
• 6. Channel 16 switch (CH 16): Press this button to switch the radiotelephone to Channel 16.
• 7. Select button (SEL): Press this button to switch the radiotelephone to the channel selected by the Channel Select Switch.
• 8. Channel Select Switch: Rotate the switch to select one of the installed channels.
• 9. Weather channel indicator: Illuminates when the Weather button is pushed, indicating that the radio is monitoring the weather channel.
• 10. Channel 16 indicator: Illuminates when the Channel 16 button is pressed, indicating that the Radio has switched to Channel 16 operation.
• 11. Transmit RF indicator: Glows indicating that actual RF is being transmitted.
• 12. ON/OFF indicator: Indicates if power has been applied to the set.
• 13. Auto-Dimmer Photosensor: Senses environmental light for the Auto-Dimmer system.

Additional Controls

1. Microphone Hanger Box: Triggers the Channel 16 Auto-Monitor circuit when the microphone is replaced in the hanger.
2. Handset Cradle: When the optional Handset is used, the internal switch mutes the front speaker and applies audio to the handset speaker. When the handset is replaced in the cradle, the internal switch turns on the front speaker and triggers the Channel 16 Auto-Monitor circuit.

Image description: Front view of the Icom M25D transceiver with controls numbered according to the operation section. Also shows an optional handset and cradle.

Operating Instructions

The Channel 16 Auto-Monitor: The ICOM M25D Channel 16 Auto-Monitor circuit simplifies operation of the radio by automatically switching to Channel 16 when the mic or handset is replaced on its hanger. However, even with the mic or handset in its hanger, any channel on the channel select switch [8] or the weather channel can be monitored simply by pushing the appropriate button.

1. Press the Power On/Off switch [1] to the On position. Both the On/Off indicator [12] and the Channel 16 indicator [10] will be lit. The set is on and monitoring Channel 16.
2. Turn the Volume Control [3] fully counter clockwise.
3. Turn the Squelch Control [4] fully counter clockwise.
4. Turn the Volume Control [3] slowly clockwise until you reach a comfortable level of noise, if no signal is present, or audio if a signal is present.
5. Turn the Squelch Control [4] carefully clockwise until the noise just disappears (approximately the 3 o'clock position). The radio is now set and will remain quiet until a signal appears.
6. If you wish to monitor one of the installed channels, simply push the Select button [7] and rotate the Channel Select switch [8] to the proper channel.
7. If you wish to monitor the Weather channel, simply press the Weather button [5]; the set will switch to the weather channel and the weather indicator [9] will be lit.

To Transmit

1. Push the Select button [7] and rotate the Channel Select Switch [8] until you find an empty channel that can be used for the type of communication you wish. Be sure the channel is open.
2. Push the Channel 16 switch [6], and after confirming that it is open, call the party you wish to contact. When contact is made, go to the channel on the Channel Select Switch [8] you checked before.
3. Hold the mic fairly close to your mouth and speak in a clear, natural voice. When you have finished your part of the conversation, release the PTT switch on the microphone, and the radio will receive.
4. When your conversation is completely finished, replace the mic or handset in its hanger, and the radio will automatically return to Channel 16.

Before Transmitting, ensure the HI-LO power switch [2] is in the proper position for the distance and needs of your contact. Use 25 watts only when necessary, to avoid interfering with others trying to use the same channel in another area.

Operating Rules and Guidelines

Prevent Interference

Before transmitting, monitor the channel you wish to use to avoid interrupting transmissions in progress.

Call Procedures

Calls must be properly identified and time limits must be respected.

1. Give your call sign each time you place a call to another vessel or a coast station. (If a call sign has not been assigned, identify the station by announcing the vessel name and the name of the licensee.)
2. Give your call sign at the end of each transmission of more than 3 minutes duration.
3. You must break and give your call sign at least once every fifteen minutes during long ship to shore calls.
4. Keep your unanswered calls short (less than thirty seconds) and do not repeat a call for two minutes.
5. Unnecessary Transmissions are not recommended.

Priorities

Read all the rules and regulations pertaining to priorities and keep an up-to-date copy handy. Safety and Distress take priority over all others. You must monitor and be able to transmit on 156.8MHz, Channel 16. False or fraudulent distress signals are prohibited and punishable by law!

Privacy

Information overheard but not intended for you cannot lawfully be used in any way. Indecent or profane language is prohibited.

Logs

Use of this equipment requires entry of the watch period of 156.8MHz (CH 16) by the operator with vessel name, call sign and operator signature. All distress, emergency, and safety messages must be recorded in complete detail. Log date activity is usually recorded in 24 hour time. Universal Standard Time (formerly GMT) is frequently used. Adjustments, repairs, channel frequency changes and authorized modifications affecting electrical operation of the equipment must be kept in the equipment log and entries signed by the authorized licensed technician performing or supervising the work. This is done in the equipment log, a small section is included in the back of this manual. Contacts are recorded in a communication log.

Image description: Sample layout for a communication log, with columns for Date/Time, Channel, Vessel, Remarks, and Operator.

Channel Usage

A channel selection system, frequency-usage, has been internationally adapted for the marine VHF band. Each frequency within the spectrum has been assigned a channel number, for example, 156.300 is Channel 6. Specific purposes have been assigned to each channel under this system, i.e., inter-ship between two vessels and ship-to-shore. Geographical locations have specific channels assigned for use with the land telephone system.

Your selection of channels to be installed should be based on the type of contacts you plan to make within the areas you live or travel to. The chart on the following pages will aid this selection. Each geographical area has specific channels assigned to it for use with the land telephone system.

Be sure to review the channels you should have installed in your radio to give you the capability to make the type of contacts you want in the area where you live or plan to travel. Study the chart on the following pages, showing the available channels and their usage.

User Tips

Battery

Prevent battery drain during prolonged transmissions by keeping the vessel's engine running.

Dead Spots

Topography may prevent reception and/or transmission from some locations. Move to another location if you find a "dead spot".

Routine Maintenance

Your ICOM transceiver is designed to provide high quality performance for many years if cared for in a normal manner. Each year, you should have the following checked by a licensed technician to verify your unit's performance:

1. Check antenna system.
2. Verify transmitter frequency, deviation, and power output.

Battery voltage should be checked often. Your electrical system should be checked if voltage is less than eleven volts or more than sixteen volts at the radio.

Marine VHF Radiotelephone Channel Frequencies

Minor Trouble Shooting

Your IC-M25D has been design-engineered to provide years of trouble-free operation. This has been made possible through the use of the most current technology along with ICOM's years of experience in the production of high quality, dependable VHF/FM equipment. Your IC-M25D has been specifically designed to withstand years of use in many different, extreme environments.

However, as with all marine electronic equipment, it is possible that some problems may occur that would interfere with the operation of the set. Should such a problem occur, it is recommended that your unit be taken directly to your ICOM dealer or authorized ICOM repair service center for qualified service.

Some problems may occur which may interfere with the operation of the radio that are not directly related to the electronic circuitry within your set. Below is a brief description of common problems outside of your set that may occur, and means of identifying them.

1. Antenna: If it appears that you are having unusual difficulty in transmitting or receiving properly, it is possible that the cause is due to a defective or faulty antenna system. The most common problems that occur with antenna systems include broken or shorted antenna cable runs, or corroded or defective connector installation. Double check to be sure the connector is soldered to the connector and that it is not shorted. Visually inspect these items to help isolate the problem. A qualified technician should correct the antenna problem.
2. Power loss: If, upon turning your radio to the On position, the pilot lights fail to light and no sound is heard from the radio, a common problem is low or no power from the battery source in the boat. Visually inspect the power cable from the battery for broken or short leads. Also, inspect the fuses both in the vessel's "fuse block" as well as the fuse in the power cable on the radio for corrosion or a blown fuse.
3. Microphone cable: If, in transmitting, either the voice is not heard or the transmit light is not lighting, the problem could be in the microphone cables. Inspect the mic cables for possible breaks or tears that could be the source of the problem. If such is the case, replace the mic cord.
4. Ignition noise: Occasionally ignition noise from operation of the vessel's engine and/or occasionally refrigeration or power generating equipment may cause static interference with your radio. Ignition noise, alternator "whine", and spurious signals from other electrical devices may be found and cured by experienced technicians using known techniques and noise reduction devices.

Transmitter Log

A template for recording transmitter performance data.

Emergency Use

If your vessel requires assistance, attract the attention of other vessels and the Coast Guard by sending a distress message on Channel 16.

Procedures for sending a distress signal:

1. MAYDAY, MAYDAY, MAYDAY (repeat three times)
2. THIS IS (name of the vessel)
3. LOCATED AT (gives position)
4. Give the reason for the distress call.
5. Explain what assistance you need.
6. Give additional information to help those come to your assistance, (vessel length, color, type, etc.)
7. Use Channel 16 only to make initial contact.
8. After making initial contact, agree on an alternate frequency, such as Channel 22A or Channel 6, and clear Channel 16 for other traffic.

ICOM INCORPORATED, 1-6-19, KAMI KURATSUKURI, HIRANO-KU, OSAKA JAPAN