Note
While the core tuning algorithm remained similar to the original AT-11, the user interface and physical construction saw significant upgrades. The MP was offered fully assembled or in kit form, feature increased power capability, added a cross-needed meter, an interface for connection to compatible radios, and had a more finished appearance.
The AT-11MP is a full-featured auto or semi automatic antenna tuner designed for HF (1.8 to 30 MHz) transceivers using between 5 to 150 watts. The tuner uses a switched “L” configuration with 256 capacitor, 256 inductor and Hi/Lo-Z settings to provide over one hundred and thirty thousand tuning combinations. The tuning range is 0 to 3900 pf and 0 to 20 uH. The “L” network works with just about any coax fed antenna (dipole, vertical, beam, etc). Users with long wires can install a balun between the tuner and the antenna. Tuning time is between 0.1 and 6.0 seconds with the average being about 2.5 seconds.
A cross reading dual needle meter will provide an indication of SWR while RF is present and DC power is on. Since the power is actually calculated in the processor, the meter does not function with the power off.
The Auto/Semi switch controls how the tuning process will be envoked. In Auto mode (Auto/Semi toggle switch in Auto), the tuner will seek a 1.5 match (or better) anytime the SWR rises above3.0. In Semi mode (Auto/Semi toggle switch in Semi), the tuner will seek a match only when the Tune push button is pressed. Both modes require that more than 5 watts of RF power be present.
On the back panel is the Radio Interface. This works with radios that are compatible with the Icom AH-4, Alinco EDX-2 and Kenwood AT-50 tuners. When connected to a compatible radio, it enables the “Tune” button on the radio. Pressing the Tune button on the radio will cause the radio to temporarily switch modes to CW, transmit 10 watts and start the AT-11MP tuning cycle. Once the tuning cycle is complete the AT-11MP will signal the radio that the tuning is complete and the radio will return to the previous mode and power settings.
