Icom AH-4 Manual Tune Initiator

I wanted a simple way to use my Icom AH-4 Tuner with my Yaesu FT-101E, and I’d previously seen a simple push button style setup over at JA1EAC’s Blog.  Details as follows (click on the photo for more).

JA1GAC  also published a more complicated circuit, but I based mine on the generic setup he published, due to the fact that tuning up a Hybrid Rig such as the FT-101E involves a number of steps anyway, and his more complicated setup wouldn’t offer any real benefit.  The generic circut that looks like this, however I added a power switch & power on LED:

Generic AH-4 Tune Start Circuit

The power on LED was simply a matter of an additional 2K  resistor (I used 2.2K as I had them in my junk box) and another LED wired between the power switch and ground.

The circuit is nice and simple and works really well with the FT-101E.  Using the ICOM AH-4 is as simple as pressing and holding the start switch until the tune indicator LED comes on.  As the AH4 will only tune with a 5-15 Watt input signal, it is easy and convenient to do this just after the initial low power tuneup is done on the FT-101E (as per the manual).  Once the AH-4 has tuned (indicated by the tune indicator LED going out WITHOUT flashing), the rig is then tuned for Peak Output.  Tuning this way has the advantage only tuning for peak output once the AH-4 has found a match.  Lastly, if the AH-4 fails to tune (mostly due to to high an input power), the LED with flash quickly before going out.

I hope this helps some one as much as JA1GAC’s blog post helped me.  Be sure to check out the link to his blog above if you wish to make a more advanced Tune Initiation circuit more suited to a newer (non hybrid) rig.

73s to you and yours,

Jarrad VK3HXT


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