HF Automatic tuner


Introduction :

Generally Automatic Atu are very expensive.

However the atu is composed essentially of relays commanding inductors and capacitors. Most of the time the L match circuit is used. For several months I have been thinking about a way to make one around an Arduino and using economic cards.  It will not be necessary to spend more than 70$ for an ATU of 100W.

In addition it can be installed outdoors and controlled remotely by an rs485 link

ATU characteristics:

  • Modular design.
  • Up to 100W or more (not tested)
  • Tandem match detector
  • Arduino nano CPU.
  • Remote controller by RS485
  • Balun integrated symmetric and asymmetric output
  • Can be installed outdoors
  • SWR and POWER meter.
  • Ajustable trigger power (lower than 1W)
  • Simple protocol between ATU and remote control
  • Cost 70$ max without box

The ATU is based on modular cards:

  • Arduino
  • 12V Relais x8 (two cards)
  • 12V Relais x2
  • 4×20 LCD display.
  • PCF8574 expander.
  • Specials PCB for detector

Pcb available mail me :  f4goh@orange.fr

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HF Automatic tuner