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Thread: icom ah-2

  1. #1


    Hello everyone!

    I just received an Icom ah-2 from a friend of mine, that had gotten it when he purchased a marine rig from a friend. Unfortunately, it did not come with anything but the tuner module. I was wondering if there is a way to make an interface for it that will allow me to connect the rig to it. I am also less the manual and schematics for it. I have searched on the web and was unsuccessful finding one.

    Any info is appreciated.


  2. #2


    An AH-2b is the 2.5 meter long antenna element (whip antenna) for mobile operation with the AH-4 tuner.

    The AH-4 is Icom's premier (HF and 6 meter) automatic antenna tuner. #Frequency coverage for the AH-4 is 7 to 54 MHz with the AH-2b whip antenna (3 - 54 MHz with a long wire). #A shielded control cable (Icom part # OPC-420) connects the AH-4 tuner to many Icom radios. #This cable provides the proper interface (voltage, ground, start and key) from the radio to the tuner.

    Your description sounds like you have both the AH-4 and the AH-2 ?

    The AH-4 manual is available on the Icom America web site:

    Select: #Support --> Documents --> Scroll down to Options and Accessories (AH-4 is the first entry). #The file is in Adobe Acrobat "PDF" format

    If you still need a paper manual or tech support:

    ICOM America's Technical Support-by-Phone please call (425) 454-7619, Monday - Friday, 8:00 AM - 4:30 PM Pacific Time. (Please note: this free support-by-phone service is extremely popular. You may have to wait on hold during peak business hours.)

    ICOM America, Inc.
    2380-116th Ave NE
    Bellevue, WA 98004
    Phone: (425) 454-8155
    Fax: (425) 454-1509
    Customer Service: (425) 454-7619

    E-mail addresses:


  3. #3



    Thanks for the reply, but it seems that you are jumping the gun. I am positive that I have an ic-ah2, i would like to know if the main unit is usable without the smaller unit or not. On the following link you will see #the ah2 with a small box next to it. I want to know if anyone knows what it is used for, and will the whole unit work without it. I had called Icom many months back to see if the box was still available, but I was told it is no longer carried. The person I received the unit from has misplace the manual. I am asking for help before I call icom for the manual and the schematics.


  4. #4


    Jason -

    The photo did help, forgot about this model (popular with boaters using the IC-735)

    Here is an valuable web site you should bookmark:

    So you have the earlier model (IC AH-2).

    The "controller unit" (AH-2a) is 2.1" (W) x 2.5" (H) x 8.1" (D) in addition to the standard tuner (AH-2b).

    The AH-2 was designed for the IC-735 transceiver.

    Here is the hookup diagram for the Controller and Tuner Units with the IC-735 transceiver (note the controller unit):

    This controller (AH-2a) fits to the side of an ICOM 735 SSB/Ham radio and generates a signal that is used by the tuner (AH-2b) to auto tune the backstay. #The 735 does not have a built in signal generator like most of the other Icom transceiver models. #Bob Grove still has this controller box available (bargain bin) at:

    Later brochure for the Icom AH-2a model
    [Front page]
    [Back page]

    Additional links:

    --------------------------------[no warranty]------------------
    Double check with Icom technical support (or a schematic), BUT IF you use this unit with the Icom 706, and connect the control cable(4 pin molex connector), from the back of the AH-2 controller to the "like connector" on the rear of the IC-706. The 706 tuner button now becomes the control button for the AH-2 (or AH-3).

    The 4 conductor interface from the radio to the tuner is (voltage, ground, start and key).

    Use the AH-2 (or AH-3) as described in the IC-706 instruction manual.

    73 de w9gb

  5. #5


    Thank you very much, you have been a big help. I was going to ask about the 706, but you beat me to the punch. I will have to order the tuner control for my other rigs. At 29.95, you can't beat that.

    Thanks again


  6. #6

    Thumbs up

    Jason -

    Unless you will operate the AH-2 with an Icom IC-735 transceiver or desire to have the complete system (for future sale), you do not need the controller for other Icom transceivers. #[It was lucky that I saw Bob Grove had one of these controllers earlier this week.]
    You would have to check with Icom, if the controller allows other transceivers (e.g. Kenwood, Yaesu) to operate with this tuner.

    I already mentioned the IC-706 interconnection. My Icom 756Pro has the 4 connector Molex plug for connecting a AH-2, AH-3 or AH-4 automatic tuner at the bottom center of the back panel .

    Best wishes.

    73 de w9gb

  7. #7


    I did find that K9EQ has built an AH-4 interface so that it can be used with other transceivers. #You may wish to look at this web page for more information. #The AH-2 was the earlier version of this current automatic tuner (AH-4).

    The AH-4 Interface

    Q: How does the AH-4 differ from the AH-3?

    A: #The wiring is identical and I assume that the AH-3 will work where ever the AH-4 will and visa versa. I did notice, however, that the 706 MKIIG implements some special circuitry just for the AH-3. It is not clear to me why this is done. The main difference from the user's point of view is that the AH-3 is specified to operate on 160 meters, while the AH-4 eliminates 160 and includes 6.

    73 de w9gb

  8. #8


    Thanks for the feedback. I did call icom to see if the ah-2 is compatable with my icom 706 and 737a. They told me that there should be no problems that the pinout is the same for all the icom tuner units. I did try the unit with a 25 foot wire and it only seemed to tune 15m. I'll play with it a bit more to see if there is a problem or not.


  9. #9

    Default AH-2 occasionally fails to tune 80 & 40m

    My AH-2 is connected to a 27m sloping wire. Since a while it fails to tune in the 80 & 40m bands. The tuner is mounted outside, on the roof of my house. I found that when the sun shines on the tuner and "warms" it up, it does tune on 80 and 40m.
    Does anybody know this problem?
    73 Werner HB9US

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