Review of the LDG Electronics AT-11MP
I started looking over automatic tuners recently, primarily to match the antenna system I use when mobile. The bandwidth of the antenna is fairly tight, especially when used on 40 meters. In fact, I was only getting a good SWR over about 15 khz of the band. I have been using an MFJ tuner at home to match to a wire antenna, but it would have been suicidal to attempt manual tuning in a moving vehicle.
The reason for considering the LDG electronics automatic tuner is immediately obvious in the price. It is, by a good margin, the cheapest of the automatic tuners. After reading several reviews on the Internet, I decided to order one (the AT-11MP, which includes a standard cross-meter). I also bought the cable required to link to the Icom 706, although it can be used with any HF rig. With a rig without a tuner button, you would need to push the tune button on the panel.
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| After experiencing the ease of auto-tuning, I strapped and grounded the tuner to the ICOM-706 for both mobile and fixed operation. |
A remote panel, including meter, is available for automotive and other applications. Unlike some other auto tuners, the cabinet is not designed to be mounted outdoors at the antenna feed point.
As far as evaluating the tuner (or "antenna matcher" if you prefer), I compared it on my home station with the MFJ tuner. I would say that the automatic technique often beat out my own tuning attempts. Since there are usually several combinations of inductance and capacitance that get close to the lowest SWR, I'd often stop before actually reaching the lowest SWR on the MFJ. On the other hand, there were a few circumstances with difficult to match antennas that the auto tuner took several tries to get a low SWR, and the MFJ, after a lot of adjustments, came out ahead. The bottom line, however, was that I got so used to the ease of auto tuning that I didn't even want to twist the controls on the MFJ anymore. So, the AT-11MP travels in and out of the house with the 706, which is my only HF rig.
The tuner improved the mobile setup. I could cover all the of the 40 meter band without having to tune the whip part of the coil. I also was able to tune the 10 meter SSB coil for 10 meter FM, at 29.660 Mhz. Furthermore, it was possible to tune to the 12 meter WARC band on the same coil.
An odd feature of the auto tuner, which takes some getting used to, is the relay clatter at tune-up. While microprocessor controlled, it is conventional relays that are controlled. So, for the 10 or so seconds it takes to arrive at the lowest SWR, the tuner fires off a staccato burst of relay clicks.
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