Inside The Ah-4 - Icom AH-4 Manual

3. Inside the AH-4

I use the AH-4 primarily to feed balanced antennas. I've modeled a number of antennas using EZNEC
and I never seem to have good luck when the antennas are unbalanced. An example of an unbalanced
antenna is a long wire connected to the RF out port and the ground connected to, well, ground. I
much prefer feeding either a loop, with the AH-4 right at the feed point, or a flat top via ladder line. In
both these cases the AH-4 works extremely well.
This is a photograph of my AH-4. It is feeding a 30 meter flat top. The antenna is about 20 meters high
and is fed with 450 ohm ladder line.
Note that the RF output is on top and the RF ground is on the bottom. I'm not sure why they did this. It
makes one believe that the tuner cannot work with a balanced feed. Nothing could be further from the
truth. It works great. Note that the metal mounting brackets are not grounded.
FIGURE 2: AH-4 IN OPERATION CONNECTED TO BALANCED ANTENNA
AH-4 Operation K9EQ
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