To Next PageTo Next Page
Need help?Do you have a question about the Icom AH-705 and is the answer not in the manual?
Key characteristics of the AH-705, including IP54 rating and power options.
Guidance on proper disposal of electrical products and batteries in the EU.
Declaration of conformity with EU directives for the AH-705.
Definitions for warning symbols (DANGER, WARNING, CAUTION, NOTE).
Essential safety warnings for using the AH-705, including RF voltage.
Safety guidelines for handling and using batteries with the device.
List of items included with the AH-705 antenna tuner.
Optional accessories available for purchase for the AH-705.
Instructions for installing and using AA alkaline batteries.
Instructions for connecting and using an external DC power source.
Diagram and explanation of how to connect the AH-705 to antennas and transceivers.
Steps for physically mounting the AH-705 antenna tuner, often on a pole.
Step-by-step guide on how to operate the AH-705 antenna tuner.
Technical details and performance characteristics of the AH-705.
Information regarding the device's compliance with FCC rules.
The Icom AH-705 is an automatic antenna tuner designed to provide reliable matching for a wide range of frequencies, from 1.8 MHz to 54 MHz, when used with a long wire antenna element. Its primary function is to optimize the impedance of the antenna system, ensuring efficient power transfer from the transceiver to the antenna and minimizing Standing Wave Ratio (SWR).
The AH-705 automatically tunes the antenna system to achieve an SWR of less than 2:1, typically within 2 to 3 seconds under general conditions, and a maximum of 15 seconds. This automatic tuning process is initiated by the connected Icom transceiver, which transmits a low-power signal (5 W for IC-705 versions 1.20 or later) while the tuner adjusts its internal components. During tuning, a side tone is heard from the transceiver, and a "TUNE" indicator blinks. Once tuning is complete, "TUNE" is displayed. If the tuner cannot reduce the SWR to less than 2:1 within 15 seconds, the indicator goes out, and the tuner is bypassed, directly connecting the antenna to the transceiver. The tuner utilizes latching relays, which contribute to its low power consumption and memorize the operating state, though strong impacts may cause settings to be lost.
The AH-705 can be used with various antenna configurations, including long wire antennas and HF/6m antennas. For optimal performance, the antenna tuner requires an adequate ground connection. Connecting a heavy gauge wire or strap to a long ground rod, with the shortest possible distance between the [GND] terminal and the ground, is recommended. A long wire connected to the [GND] terminal can also serve as a counterpoise.
The AH-705 offers flexible power options, allowing it to be powered by two AA (LR6) size alkaline batteries or an external DC power source (13.8 V DC ±15%). When using alkaline batteries, it's crucial to install them with correct polarity and ensure they are all of the same brand, type, and capacity, avoiding the mixing of new and old batteries. For external DC power, users must build a power cable and connect it to the [DC IN] jack, confirming the external power source is OFF before connection. The center pin of the DC plug is positive.
The device is designed for outdoor installation, typically mounted on a pole using the supplied bracket and a user-supplied strap. It can also be hung by threading a cord through the bracket. It is important to keep the antenna tuner as far away from the transceiver as possible to minimize interference.
The AH-705 is controlled directly from a compatible Icom transceiver. To initiate tuning, users typically turn on the transceiver, select an operating frequency, push the FUNCTION button, touch the appropriate screen icon (e.g., "2" at the bottom of the screen), and then touch [TUNER]. Touching [TUNER] again will toggle the AH-705 ON or OFF (bypassed). For manual tuning, the [TUNER] icon can be touched for 1 second.
For IC-705 versions 1.20 or later, the tuner's transmit power is automatically set to 5 W during tuning. These versions also include a Tune Memory function, which can be turned ON or OFF, to save latching relay combinations for quicker antenna tuning. Furthermore, the firmware of the antenna tuner can be updated via the transceiver, adding new functions and improving performance.
The AH-705 features an IP54 dust protection and splash resistance construction, which is effective only when the jack covers are attached. This makes it suitable for outdoor use, but it should be protected from heavy rain and never immersed in water. If the tuner has been dropped, its dust-protection and splash resistance cannot be guaranteed due to potential damage to the case or waterproof seal.
For cleaning, the tuner should be wiped with a dry, soft cloth if it becomes dusty or dirty. Harsh solvents like Benzine or alcohol should not be used as they can damage the tuner's surfaces.
When the antenna tuner will not be used for a long period, it is recommended to remove the alkaline batteries to prevent leakage and damage. If the installed alkaline batteries are almost exhausted, the antenna tuner will automatically turn OFF, signaling the need for replacement with new batteries. Disconnecting the control cable from the antenna tuner when not in use for some time will also prevent the installed alkaline batteries from becoming exhausted.
Users should regularly check the wire length and connection of the antenna, as the AH-705 cannot tune a wire that is a half-wavelength or a multiple of a half-wavelength at the operating frequency.
Safety precautions are paramount. Users must never touch the antenna or antenna connector while transmitting or tuning due to high RF voltage, which can cause electrical shock or burns. The antenna tuner should not be installed where people can easily touch the antenna or connector during operation. It should never be used during a lightning storm, and the power source and antenna should always be disconnected before a storm. The tuner should not be handled with wet hands, and AC power or more than 16 V DC should never be applied to the [DC IN] jack. Correct polarity must be observed when connecting the DC power cable. Metal, wire, or other objects should not contact the inside of the tuner or make incorrect contact with connectors. Finally, the antenna tuner should always be operated with a solid ground connection.
General| Type | Automatic Antenna Tuner |
|---|---|
| Tuning Method | Automatic |
| Impedance | 50 Ω |
| Power Supply | 13.8 V DC |
| Minimum Input Power | 5 W |
| Antenna Connector | SO-239 |
| Tuning Time | Approx. 2 to 3 seconds |
| Matching Impedance Range (HF Bands) | 16 Ω to 150 Ω |
| Control Interface | CI-V |
| Operating Temperature Range | -10°C to +60°C |
