Automatic matching devices are very rarely found in homemade radio amateur designs. As a rule, radio amateurs use homemade external hand tuners or purchased automatic ones. The proposed device, developed by David N7DDC, due to its small size, low cost and simplicity, can be used as a standalone device or built into existing structures with output power up to 100 watts.

Main features of the ATU-100 MINI 5 × 5 auto tuner:

Works at frequencies 7-10mhz

Permissible Supply Voltage Range: 10 - 15 Volts DC

Maximum current consumption: 300 mA

Maximum working power throughput: 100 watts

Maximum measured power is 150 watts

Minimum power required to start setting: 1 watts

Minimum possible measured power: 0, 1 watts

Measurement step at power up to 10 watts: 0, 1 watts

Measurement step at power exceeding 10 watts: 1 watts

Power Measurement Accuracy: 10%

Maximum set inductance: 4 μH

Minimum step of setting inductance: 0, 1 μH

Maximum installed capacity: 400 pF

Minimum capacity setting step: 10 pF

The board has a microprocessor control, five inductors, five high-voltage capacitors, relays for their switching, relay control transistors and a scheme for measuring the direct and reverse power of the type "tandem match". The usual "G-shaped" matching scheme is used. The tuner can be used as an external in a separate housing, including remotely for tuning directly from the antenna.

To start the matching process, just press the button connected to the corresponding socket or close the output with the transistor if it is possible to control the tuner from the transceiver. The unique smart algorithm used in the device allows in most cases to adjust in 0.1 - 0.5 seconds, and the maximum time spent searching for the best combination does not exceed 2 seconds. Thus, there is no need for any additional measures to speed up the work, which makes the device extremely simple and reliable.

The device allows to connect to the socket for programming of the processor standard two-line display with the control bus I2C, which displays the most important information (output power, SWR and the nominal capacitance and inductance set in the process of coordination).

There is a simplified three-level LED indication of the result of antenna matching (SWR <1.1, SWR <1.5 and SWR> 1.5). This can be useful when using a tuner as a homemade amplifier or to control a tuner remotely located. Another option is to connect an LED, a two-color red LED with a common anode to the output terminals of the processor to program the processor. zero, connect anode anode to VCC (+ 5v), green cathode through current-limiting resistor to connector CLK, cathode red LED through current-limiting resistor to DAT connector without fear of clashing obrazom LED y ou generirovaty 3 color svecheniya, zelenыy, oranzhevыy and Krasnye depending on the SWR in line with kotorыm bыl and payable protsess soglasovaniya (settings).

There are 3 control buttons in the tuner - besides the main button "TUNE" (it is also briefly pressed RESET button) now added two more buttons that can be brought to the front panel, this is the button "AUTO" (automatic tuner tuning mode) and "BYPASS"

The tuner remembers the last settings and restores them after power-up. Fast Test mode is turned on when power is applied to the device with all three Tune, Bypass and Auto buttons pressed. In this mode, the device supplies power to all relays, allowing you to quickly identify faults associated with transistor keys or brazing defects. When power is applied to the device with the Bypass and Auto buttons pressed, the device enters Test Mode. In this mode, it is possible to manually switch the capacitance or inductance values ??using the Bypass and Auto buttons. Long press on the Tune button allows you to select which elements will be moved at the moment, and a short press changes the connection point of the capacitor. In this mode the ability to measure input power and SWR in the line remains. The whole process is accompanied by a clear indication.

Project page: https://github.com/Dfinitski/N7DDC-ATU-100-mini-and-extended-boards