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Thread: Inside The Icom AH-4 Antenna Coupler

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    4x4 Ham Member WB7X's Avatar
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    Default Inside The Icom AH-4 Antenna Coupler

    The AH-4 is an antenna coupler/tuner designed for long wire or whip type antennas.
    This coupler, like the SGC brand, are typically used at the feedpoint of the antenna, as opposed to a standard antenna tuner located just downstream of the transceiver.

    With an 8 foot "whip" freq coverage should be 6m-40m and with 23 feet of wire the range is 6m-80m.

    This is the new AH-4 that arrived today.

    In the box you have the AH-4, package of mounting bolts, package with 16' of coax and 16' of 4 wire control cable, and the instructions. The coax requires installation of the PL259 connectors.



    Bottom of the AH-4 showing the ground lug and weatherproof feed throughs for the coax and control cable.


    Rear of AH-4 showing the mounting brackets.


    Requires removal of 8 Phillips screws to get to the coax connector (shown center right) and control cable attach point (center left)

    Notice the lip molded into the cases and the gasket used for weatherproofing. The "hot" side of the antenna attaches at the top insulated feed through.






    I am first going to experiment with it on a base antenna and will be extending the
    control cable. (If I can find the flat 4 pin molex connectors somewhere).

    EDIT: 6/3/2011

    AH-4 modified with coax and control cable pigtails for ease of experimentation. Coax is standard PL-259 with
    double female bulkhead connector. Control cable uses a 4 pin male inline microphone connector.




    AH-4 control extension cable is 50' of 18/5 solid copper sprinkler wire with UV resistant jacket (Home Depot $16.50)

    Connectors are 4 pin female mic and 4 pin polarized Molex male (Radio shack #274-224 $2.50)

    I used mic connectors due to the narrower width so that they could easily be fed through the wall from the shack
    to an antenna.




    The AH-4 has now been tested with up to 65 feet of control line with no problems.
    Last edited by WB7X; 03-28-2013 at 12:56 PM.

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    4x4 Ham Member AC0VH's Avatar
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    I have a Yaesu FC-40. I have a 40 foot long control cable with no issues, although I would at minimum put a ferrite around the cable on the radio side. Long cables = antennas!

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    I also have an FC-40 and was unsuccessful when I tried a 125' run of control cable. You can find Molex connectors of all sizes at Mouser:

    http://www.mouser.com/molex/

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    Thanks for the write up. I have been thinking of getting on of these. Keep us posted.

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    4x4 Ham Member WB7X's Avatar
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    Quote Originally Posted by KC0NNT View Post
    Thanks for the write up. I have been thinking of getting on of these. Keep us posted.
    A few mods completed.

    Check EDIT to original article.

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    4x4 Ham Member KD7WCD's Avatar
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    Has anyone tried one of these type of devices with an 8' Whip on a mobile rig. I am getting tiered of changing out Ham Sticks every time I want to change bands. I really like the Performance of the Ham Sticks but just getting tiered of caring a rack full of them around.

    I was also looking at some of the smaller screw driver antennas out there but they seem so vulnerable for off roading. I like the idea of just having an whip that can take some abuse.

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    4x4 Ham Member N7BDY's Avatar
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    Very sanetary job , I like how you put connectors close to the AH-4 so you can use any length wire at a later date . I use mine with the original cables that come with it but I want to lengthen the feeds so I can put it right at the base of the antennas . I have heard of using sprinkler cable but was leary of it being a SOLID wire not stranded , maybe my fears are unfounded . The price is sure right at 16 bucks . Have you noted any problems such as its too stiff or ? ... or are you pretty satisfied with the sprinkler cable ? What coax are you using , rg8x ?

    N7BDY
    Bob

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    4x4 Ham Member WB7X's Avatar
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    Quote Originally Posted by N7BDY View Post
    Very sanetary job , I like how you put connectors close to the AH-4 so you can use any length wire at a later date . I use mine with the original cables that come with it but I want to lengthen the feeds so I can put it right at the base of the antennas . I have heard of using sprinkler cable but was leary of it being a SOLID wire not stranded , maybe my fears are unfounded . The price is sure right at 16 bucks . Have you noted any problems such as its too stiff or ? ... or are you pretty satisfied with the sprinkler cable ? What coax are you using , rg8x ?

    N7BDY
    Bob
    I wanted easy adaptability. The coax is from a double shielded 3' jumper that I had that I cut in half.

    I was surprised how limited the local wire selection was. I went with the 18/5 as the cable supplies was 20/4 and I wanted heavier. I also like the UV jacket on it. It is stiff but not bad.

    FOR KD7WCD: The AH-4 is actually marketed by Icom as a mobile tuner with an 8' whip. I purchased a DX Engineering 8' SS whip that I am using as part of a portable
    vertical and can be reconfigured to mount on the truck.

    You could also use it to tune a hamstick.

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    4x4 Ham Member AC0VH's Avatar
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    Tuning a Hamstick is less ideal than just a random wire. They have inductance where as short whips are just very capacitive. I think their best use is to widen the bandwidth of a Hamstick rather than make them tune other bands.

    The intention of these tuners, the AH-4, FC-40, EDX-2, etc., is as mobile tuners for vehicles, boats and the like. So this is really their best application. To tune short whips, hand railing, boat back stays, random length wires.

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    4x4 Ham Member KD7WCD's Avatar
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    The intention of these tuners, the AH-4, FC-40, EDX-2, etc., is as mobile tuners for vehicles, boats and the like. So this is really their best application. To tune short whips, hand railing, boat back stays, random length wires.
    How dose the RF Grounding work with this for a mobile rig? Do you just tie it in to the Chassis?
    Last edited by K7VZ; 06-10-2011 at 03:32 PM. Reason: Fixed quotes

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    4x4 Ham Member WB7X's Avatar
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    Quote Originally Posted by KD7WCD View Post
    How dose the RF Grounding work with this for a mobile rig? Do you just tie it in to the Chassis?
    Yes, you may tie it to a well grounded chassis, or run a counterpoise wire up under the frame.

    AC0VH is also correct about the maritime uses. I actually found a fair amount of info pre-purchase from a couple of boating forums.

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    4x4 Ham Member AC0VH's Avatar
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    Quote Originally Posted by WB7X View Post
    Yes, you may tie it to a well grounded chassis, or run a counterpoise wire up under the frame.
    Good point. The key is that the antenna is balanced, not 'grounded' so much. So you have your radiating element and you need to give the RF a sufficient path back to the source. Tying into the vehicle chassis is the most effective, but just like in stationary or portable installations an artificial ground such as a wire or wires works, too.

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    4x4 Ham Member WB7X's Avatar
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    Added a 60 foot longwire just below the 8' whip portion of my portable vertical.

    Played 6m during the QSO party with decent results considering the band. This setup has tuned anywhere that I have tried it (including 160M at less than 1.5:1).
    I'm actually surprised at the 160m.

    Worked 80m into Payson Saturday night. I have a buddy that lives at the airpark that just put up an Alpha Delta DX-CC.

    I am still impressed.

    More playing to do though.

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    4x4 Ham Member AC0VH's Avatar
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    Quote Originally Posted by WB7X View Post
    You could also use it to tune a hamstick.
    I have a handful of Hamsticks (I've got ones for 10m, 20m, 40m). I was messing around with them the other day and something occurred to me while staring at them. You should be wary of trying to load higher band antennas with coils on lower bands, depending on construction.

    In the case of Hamsticks some of their coils look to be small wire in tightly wound coils. I haven't cut the cover back to verify, but I'd expect they use standard enamel-coated magnet wire. Which, if so, could arc over pretty easily at higher power on low bands. There is quite high voltage present on 60, 75/80, 160 (and to lesser extent 20 & 40) when you have physically very short whips. It would not be surprising to see 1kV or more, which might be significantly higher than the enamels insulation break-down.

    If you are using a tuner with Hamsticks, probably best to use the tuner for bandwidth increases rather than making them work on bands for which they're not designed to work. In the case of a 75/80 Hamstick, a tuner is almost mandatory.

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    4x4 Ham Member N2CWI's Avatar
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    I have My 2010 JK set up with a ICOM 706MKII AH-4 tuner and a stainless whip antenna, recieved 5-9 reports operating from nevada to east coast on 10 meters.
    I'll post some pics of my install later for those interested.

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    4x4 Ham Member Premium Member KF7ORO's Avatar
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    I've been using my AH-4 at home now for a bit over a year and love it. The tuner is sitting on my roof feeding a 120' loop of wire and tunes 6m - 80m nicely.
    Brian - KF7ORO

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    4x4 Ham Member WB7X's Avatar
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    Quote Originally Posted by N2CWI View Post
    I have My 2010 JK set up with a ICOM 706MKII AH-4 tuner and a stainless whip antenna, recieved 5-9 reports operating from nevada to east coast on 10 meters.
    I'll post some pics of my install later for those interested.

    Have you tried it on any other bands while mobile with the whip?

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    4x4 Ham Member N2CWI's Avatar
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    I've made contacts on 40 and 20 meters as well.

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