Icom AH-4 Remote Tuner

My current antenna is the B.A.L. -- a large, horizontal loop that's about 150 meters of wire about 15-20 meters up in the trees around the yard.  I think it's a great all band antenna.

I buried a couple of coax runs from the shack wall to a spot about 15m away behind a large bush.  The ladder line from the loop falls down to this spot so I do not have wires directly hanging off the house (which makes the YL happy).  I was using a DX Engineering MAXI-CORE Balun and was happy with the results.  (As an aside:  I love hamfests!  I picked up this used balun for a song.)  I used this setup for a few years and have been pretty happy with the results. 

Since the loop is a non-resonant antenna, the SWR can be high.  I've been using the tuners built into my transceivers (Elecraft K2 & K3) but have been concerned about loss in the coax.  Since I only run 100 watts or less, I want every bit of power to get to the antenna and not be used to heat the coax. Placing a tuner at the end of the coax run is supposed to reduce the coax loss.  I had always planned on adding a remote tuner when the budget allowed.  When I buried the coax, I also threw in a couple of runs of CAT-5 cable that I had laying around for use for some sort of remote control.

The remote connection at the end of the coax run

I recently acquired an Icom AH-4 remote antenna tuner.  I am using one of the CAT-5 runs as the control cable for the AH-4; I simply used each twisted pair together for the power and control signals.  I no longer use the balun.

All connected and ready to go!

Since I am using this tuner with a non-Icom radio, I needed a way to tell the tuner to initiate the tune cycle.  I whipped up the circuit described as the universal controller and it seems to do the job. (Edit Jan 2019: The link to the universal controller diagram http://www.k2.dion.ne.jp/%7Esradio/AH-4En.htm no longer works!  There is a discussion on eham with a diagram that I think is similar.)  I do plan on building a better controller that will initiate the tune cycle and then key the radio automatically.

The 'controller' in the shack

I've been very happy with the tuner so far.  It finds a decent match (less then 1.5:1) on all bands and I believe it has made a difference.  I don't have empirical evidence to support that, though!  At least I no longer worry about loss in the coax...