ATU-10 - The Tyny QRP Antenna Tuner.

Oficial conversation group - https://groups.io/g/ATU100

The tuner is assembled in an affordable Chinese case 100x71x25 mm, the front and rear panels are made as PCB, in the same way as the main printed circuit board. On the front panel there is a control button, a small 0.91" OLED 128 * 32 display and a USB Type C connector, used to charge the tuner's built-in battery and connect to a computer to change the firmware.

The rear panel contains RF BNC connectors, a ground clamp and an external control interface connector that can be connected to the transceiver for more convenient control of the tuner.

The control button has only 3 functions - a short press resets the tuner and sets all relays to their initial state, in which all reactive elements are disabled and do not affect the signal flow through the tuner, a long press causes the tuner to enter the tuning mode and a very long press for more than 5 seconds causes the firmware version to be displayed on the display. The display mainly shows the current transmitter power and SWR in the transmitter cable and sometimes briefly indicates the modes.

The tuner is built on IM41 bistable relays, which means that a significant current is consumed by the tuner only for a short time during tuning; in rest mode, the tuner's relays retain their state for an arbitrarily long time, without consuming power.

The built-in battery consists of two Li-Ion 14500 batteries connected in parallel. The best examples of these (SANYO) have a capacity of 800 mAh each, the worst ones are usually 400 mAh. The tuner has 3 power consumption modes - the operating mode, when the display indicates the parameters, lasts 5 minutes, after which the tuner falls asleep and the display turns off. You can wake him up with a short press on the button. After 30 minutes of sleep, the tuner turns off completely and you can turn it on by holding the button for a long time (more than 3 seconds).

The current consumption in the operating mode is 12 mA, in the sleep mode 170 μA, in the off state 37 μA.

The main microprocessor of the tuner is PIC16F18877, another PIC16F1454 processor is used as an embedded programmer. It should be flashed once using the programmer with a special firmware, after which it will be possible to change the main firmware of the tuner as many times as necessary without resorting to special means. After connecting the tuner to the computer, a new logical disk with the appropriate name will appear in the explorer, in which you can find a link to the firmware repository. To flash the tuner, it is enough to copy the firmware file to this disk, the process takes a couple of seconds and the tuner is flashed at the same moment when the file copying is completed.

There is also space for two dual-color LEDs with a common anode on the board, they can be installed if you do not need an OLED display. The right LED indicates the battery charging process, the left LED indicates the operation. In operating mode, it blinks briefly in color every three seconds, depending on the battery charge level.